Success Under Stress: Managing and Restoring the Metroforest

SUCCESS UNDER STRESS:MANAGING & RESTORING

THE METROFOREST

byLeslie Sauer and Carol Franklin

University of PennsylvaniaGraduate School of Fine Arts

Department of Landscape Architecture & Regional Planning34th & Walnut StreetsPhiladelphia PA 19104

Prepared under Grant No. 87-4251-0067of the Design Arts Program

National Endowment for the ArtsRoom 625, 1100 Pennsylvania Avenue, NW

Washington DC 20506

28 February 1989

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TABLE OF CONTENTS

-,-Introduction 1

The Metroforest 3

A Proposed Approach & Framework to aForest Management & Restoration Program 11

Ground Stabilization 16

Stormwater Management 17

Excess Fill 36

User Activities Which Damage Landscapes 40

Soil Compaction 44

Dead Wood & Brush 50

Invasive Exotics 54

Landscape Management Strategies: Control 63of Invasive Exotic Vegetation

Forest Vegetation Restoration 71

Criteria for Forest Review & Evaluation 73

Replanting Strategies 80

Habitat Corridor Networks 92

Recommended Reading List 95

INTRODUCTION

There is no such thing as a preserved landscape, any more than a human being can bepreserved, frozen in time. We can dedicate parkland and restrict development fromselected natural areas, but this does not eliminate continued impacts from surroundingdevelopment on a local scale or from environmental alterations on a global scale.

Those responsible for the care of protected landscapes have become increasinglyconcerned about the accelerating deterioration of their resource. At the same time, parkusage has increased dramatically. The negative impacts of use and abuse are alreadysadly apparent in urban parks and are becoming increasingly visible in suburban andrural areas.

Natural areas are sometimes seen as "maintenance" liabilities. Further acquisition ofpreserved land may be restricted by the unWillingness of agencies to be responsible fortheir care. The situation is even worse on developed lands, where there are virtually noprovisions for the protection of natural habitats.

And in the meantime, native habitats are everywhere declining and the rate ofdeterioration is accelerating. Over half the planet's trees have been cut since 1950. Formillions of people, contact with the natural world, restricted to public parks and remnantwildlands, is an increasingly diminished experience. From New England to the southalong the East Coast, the fate of our forests is in our hands. Rural areas areexperiencing rapid suburbanization, a fragmenting and displacing the remainingwildlands. In smaller cities like Wilmington, we are just beginning to see the problemsthat plague larger cities like Philadelphia, and for the serious time traveler, there is NewYork City, where the forests of our future can be seen: the metroforest.

Park users and managers alike are growing aware of the urgency of the problem, butare hampered by the lack of information and experience in recognizing and dealing withthe management and restoration of disturbed landscapes. Natural resource managersmay be trained to work with natural systems, but often have no familiarity withdisturbance ecology. Horticulturalists usually are even more poorly equipped. There areno consistent policies or proven methodologies that deal with disturbance anddeterioration. Despite this, many people are tackling these problems and getting goodresults for their efforts. Progress is not necessarily smooth and transformations are notinstantaneous, but the deterioration can be stopped and improvements can be initiated.

The art and science of the care of the metroforest are being developed right now byconcerned managers, who are monitoring, studying, maintaining, replanting, andexperimenting in urban forests. They are aware that restoration is an on-going job, thatnatural systems are often too compromised to expect them to recover if simply left ontheir own. This manual is intended to assist in this restoration process, providing an

Success Under Stress: Managing & Restoring the Metroforest 1

approach for assessing each site, guidelines for determining management goals, andan overview of appropriate management and restoration techniques.

Most of the material presented here will hopefully need updating within a short period oftime, as the actual management of natural systems creates numerous demonstrationareas for applied research and increases our stock of knowledge and experience.

Unfortunately, many of the problems of urban forests go far beyond the scope of thismanual. Many of the more intractable problems facing landscapes are linked to largersocial issues, which are not yet being satisfactorily resolved. Trampling resulting fromencampments by the homeless, for example, is not simply a landscape managementconcern, but requires a concerted effort from a broad spectrum of people and agencies.Landscape managers must add their voices to those seeking positive change or elseface a hopeless task.

The format of the manual includes both a discussion of the larger issues to give acontext for decision making as well as descriptions of specific approaches andtechniques. Several case studies are reviewed and recommended managementprograms are delineated for a variety of landscape types which are generic to urbanareas.


THE METROFOREST

Prior to settlement by Europeans, the entire megalopolitan region was blanketed byforest which was broken only by rocky outcrops, large rivers, and coastal wetlands. Withthe onset of lumbering and agriculture, the land was cleared and the houses, towns,pastures, and croplands of northeastern America were carved out of the forest andmaintained through constant effort at controlling natural growth. In the mid-nineteenthcentury, this intensive pressure was partially diverted by industrialization andsubsequent migration to the cities, as well as the opening of rich farmland in themidwest. Farms were abandoned and the total amount of forested land in the eastslowly increased until just recently. At the same time, many park systems, both publicand private, were established, especially in valleys, as the importance of the role offorests in protecting water quality and regulating the flow of surface and ground waterswas recognized.

The returning forest is different, however, from that which greeted the 18th-centurysettlers. The unbroken forest expanse has been replaced by small islands, each withlittle or no forest interior and cut off from other forest systems. Today's forests generallyhave been restricted to less productive land: the rocky outcrops and steep slopes notsuitable for farming or development. The landscapes around us are also younger, andthere are many miles of "edge", an increasing habitat that favors species which werelimited in older forests. Hundreds of new species of both plants and animals have beenintroduced on a large scale, both deliberately and accidentally. Some have joinednative communities, like the bird cherry, and are hardly distinguishable from indigenousspecies in their behavior. Others, such as Norway maple, kudzu, honeysuckle, andAsian knotweed, have experienced population explosions, away from their naturalcontrols, and are spreading so rapaciously that they are overwhelming many stressednative plant communities. Similarly, some diseases and pests introduced from abroadhave found unresistant hosts here, eliminating several important native species. Thechestnut and elm now make token appearances in landscapes they once dominated.

Virtually all remaining native and volunteer landscapes occur in the fabric of developedland and have recently been subjected to rapid changes in environmental conditions,including major alterations in the hydrologic cycle, soil disturbance from vegetationclearance, increased erosion, trampling, and air and water pollution.

The look of the 'metroforest' is familiar to all of us. The ground is most glaringly differentin appearance from that of an undisturbed forest. Litter is often ubiquitous and mayrange from abandoned cars and dumped construction rubble to larger particles of urbansoil, including broken glass, paper bits, and cigarette butts. Bare soil may be exposedoften over a large area, resulting from trampling, stormwater runoff, filling or excavation.In urban areas, wildlands may also provide temporary shelter to the homeless and toiletfacilities for many users.


Where disturbance is chronic, invasive exotic vegetation may prevail, typically inmonospecific stands. Even where forest persists, alien vegetation is almost alwayspresent and is usually increasing. Large relic native canopy trees may still occur, buthave long since ceased reproducing. Volunteer saplings of cherry and locust, usuallytypical of young field landscapes, may fill the large gaps in the canopy. Norway maplefrequently can be found in every layer of the landscape. Vines, both native and exotic,may occur in heaping mounds on the ground, draped over shrubs and saplings, andcloaking trees in the canopy. Ferns and woodland wildflowers may be conspicuouslyabsent or reduced to one or two species. Species diversity has usually been decliningfor years, although human use, especially for recreation, may be steadily increasing.

While nature herself is remarkably variable, disturbance is typically simplistic. Whendisturbance is uncontrolled, deterioration usually accelerates and a once rich sitesteadily diminishes in diversity, value, and interest.

There are so many sources of disturbance in the modern urban environment that it isoften all too easy to assume that solutions are too complicated to implement. Parks arefrequently perceived as becoming "unmanageable". Air pOllution, for example, is visibleand extreme, yet seems beyond a park's control. More importantly, however, is the factthat the greater share of disturbance is due to the nature of human activities, notenvironmental conditions. The same changes which are observable in urbanwoodlands can also be seen in woodlands of rural parklands as well. The intensity ofuse is certainly problematic, and a growing stress on parkland, yet this is also the veryreason most parks exist: to be used by people. A major goal of this report is to assistparks departments to confront and change those uses and activities which damage thelandscape, for urban wildlands can be sustained over time only if we succeed, throughmanagement, to prevent further damage and compensate for environmental stresses.

Despite the complexity of urban systems, there are actually only a few major stressesthat account for the bulk of disturbance. They include landscape disturbance from theoff-trail use of bicycles and vehicles, trampling, dumping stormwater management, theproliferation of invasive exotic vegetation, and the lack of maintenance and security.They must be tackled directly, for until they are resolved, true restoration will remain anillusion. Once disturbance is controlled, the landscape will become far more able torenew itself. The task of restoration is immense and recovery will not happen overnight.It is necessary to set priorities. Rather than trying to deal with everything, this programfocuses on a few critical activities, in order to effect significant changes for the better, toreverse the process of deterioration, and to initiate recovery.


SUCCESS UNDER STRESS:MANAGING & RESTORING

THE METROFOREST~ . ,

byLeslie Sauer & Carol Franklin

THE HUNTER'S FOREST

The forest before settlement was closed and dark, a place of very gradual change. Lofty white pines (1)which persist above an established hardwood canopy, and the evergreens (2) of shaded valleys recall a colderlandscape. Tall, straight trees predominate, among then the oaks, chestnuts, maples, and hickories (3). Gapsoccur infrequently in this forest. The space of a fallen tree is rapidly occupied by shade-intolerant species,such as the tulip poplar, or closed in by new growth on the surrounding vegetation (4). Where Indians haveburned (5), the landscape is open and park-like beneath a high canopy. The narrow stream is marked only by asubtle change in composition. At the water's edge, elm and silver maple are draped with vines (6).


THE SETTLED FOREST

The appearance of the settled forest is radically different from the hunter's forest, although many of thespecies are the same. The pastures and croplands are geometric in layout and the forest is relegated to linesand pockets. As soon as management of the land stopped, however, the forest came back in many differentways. The hemlocks have been spared on only the steepest slopes (1) and the hardwoods (2), sprouted fromold root stock, are brushy and many stemmed from repeated logging. A farmer's field (3), only recentlyabandoned, is once again filled with a great diversity of plants and the hedgerow (4) already grows in tightforest layers. A lone tree -- a relic of the forest -. shelters cows in a pasture. Protected from trampling,hay-scented fern (5) spreads beside an old stone wall. These stones, cleared from a field for plowing, and thedense young woodlands nearby give evidence of past farming as surely as the chimney ruins of a farmhouse.Along an early roadside (6), European weeds mingle with the briars and vines, whose tangle is yet anotherfirst step in the return of the forest. When the land was cleared, the dramatic increase in run-off andsedimentation made the stream more active. The rapidly cut and filled banks provide good habitat for willowand box-elder (7).


THE METROFOREST

The forest is completely fragmented now, confined to isolated patches and narrow corridors. The oldest,least disturbed forest persists on the steep slope, but the steady invasion of Norway maple from adjacentplantings is visible in the shrub layer (1). Fill, trash, and honeysuckle prevail at the edge but a remnantnative community struggles in the interior. The rural fields and pastures are rapidly succumbing to suburbandevelopment. Familiar pastoral elements such as hedgerows and lone specimen trees (2) now serve alandscape character for adjacent new buildings. Most reproduction of native communities is eliminated,having been replaced by asphalt, turf, or mulch bed. A few vigorous vines and garden escapees are the onlyvolunteers. In a few small park areas which have been under-maintained for decades support discontinuouswoodlands of dense black cherry and black locust amid older oaks and maple and relic privet and euonymous(3). Joggers, birdwatchers, dirt bikers, and baby carriages are all on the increase. Remnant woodlands in theurbanized areas are more dominated by non-native trees, especially tree-of-heaven and princess tree with afew tolerant species characteristic of floodplains, such as box elder (4). Horticultural plantings are typicallyconfined in beds and boxes and frequently highly maintained. the stream course is hardly recognizable, havingbeen channelized and, in places, bulkheaded. Japanese knotweed forms a continuous edge punctuated only by afew remaining sycamores (5).


Photograph: Showing a healthy, mature, oak-tulip poplar forest of the southern Pennsylvaniametropolitan area. Note the presense of 4 clearly visible layers -- canopy, understory shrub andground layers and the absence of vines, large numbers of dead and damaged trees and bare areas ordeadwood and brush on the ground.


Photograph: Illustrating initial forest deterioration. The shrub and understory layers are still in tact,but vines are beginning to move in from the disturbed edges and occasional pest species arepresent in the canopy. Unusual amounts of brush and deadwood are present and unfilled holes areapparent in the canopy, while bare areas have developed on the ground.

Photograph: Showing a highly disturbed metro-forest. Note the presense of many damaged and dyingtrees, The ground is either bare and eroded -- exposing tree roots, or covered with heaping vines. Thecomplexity of forest structure is reduced to two layers and two non-native species, Norway maple inthe canopy and Japanese honeysuckle on the ground.


Photograph: Showing a deep gully created by stormwater outflow. Urban wildlands, often found inprotected stream valleys, are especially subject to severe damage from stormwater collected at theedge of the plateau and discharged downslope from open pipes or culverts. Here, the gully has beeneroded 6 feet or more to bedrock and is draining groundwater from the surround slopes.

Photograph: Showing a trampled and heaVily compacted area at a scenic overlook adjacent to a wellused park trail. Overuse and abuse of popular visitor places has emerged as a second major cause ofdamage to the urban forest.


Drawing illustrating the difficult world of the urban tree root, where stresses range from compactionand pollution by salts above ground to minimal water, oxygen, and soil below ground. This drawing wasmade for the 1980 Philadelphia Flower show exhibit of the Morris Arboretum of the University ofPennsylvania and later became a weekly reader poster.


A PROPOSED APPROACH &FRAMEWORK TO AFOREST MANAGEMENT &RESTORATION PROGRAM

Returning complex native plant communities to the forest and with them native wildlife isusually the primary goal of those interested in restoring the landscape. Yet simplyreplanting a diversity of species on a site in which they may have thrived in the past isoften doomed to failure. Eager volunteers often plant hundreds of wildflowers in anurban woodland fragment only to find that even with vigorous maintenance almost noneare left after a few years. Elsewhere rare plants may be rescued from a site beingdeveloped and relocated to a nature preserve where they seem to thrive for a season ortwo and then suddenly disappear.

It is often very difficult for landscape managers to accept that restoration is not a simplehorticultural procedure of planting followed by maintenance. Indeed a background ingardening or horticulture often creates very false perceptions in the landscape manager,for the gardener rarely expects the landscape to become self-sustaining nor does thehorticulturalist wish the plants to breed according to their own inclinations. Thesedisciplines along with landscape architecture usually presume a high level of controlover the site and the landscape and tend to focus on the individual plant. Unsuitableconditions are changed as needed; a lot of effort is concentrated in a relatively smallarea; and it is often desirable to accomplish as much as possible all at once. Thousandsof laborers, for example, were brought into Central Park to implement Olmsted andVaux's Greensward Plan, draining swamps, and filling over barren bedrock to createrolling hills with idyllic pools and cascades along meandering streams. The Ramble, atthe Center of the Park, was planted as an idealized, romanticized forest-like landscapecrafted with the highest level skills of Victorian design. It was a triumph, and it was asignificant habitat alteration, but it was not a habitat restoration.

Landscape restoration is not about creating a complete new landscape modelled on anatural ideal, anymore than a child can be viewed as a blank form to be molded intowhatever model we select.

The most difficult obstacle to restoration is determining a restoration model that issuitable to and feasible on a given site. For any area there are an infinite number oflandscape types that might occur over time just as there are an infinite number ofcommunities that would never occur on sites with similar environmental conditions.

Some sites will be so disturbed that habitat alteration will be the most appropriaterestoration model. Restoring a sanitary landfill site to a mature forest may be overlyambitious and benefit from a shorter-term restoration model that seeks to establishnative successional plant communities which are gradually and naturally developinginto forest.


On the other hand, a healthy native mature forest may be a very appropriate restorationmodel for a degraded forest. Similarly, establishing healthy native meadows whereinvasive dominated meadows occur is probably a sounder goal than assuming atransition to a forest type, at least at the outset. Obviously a general goal is to achieve ashigh a degree of restoration possible but if our goals are too far removed from theoriginal site the necessary intervening steps may be too difficult to visualize and toocomplicated to realize. It is important to aim high, but also be aware that sustaining everlarger areas of healthy native communities is a very high goal. Just turning the cycle ofdestruction into a cycle of restoration, however slowly, would be an extraordinaryachievement. As a general rule of thumb it is probably advisable to initiate recovery overas large an area as possible rather than focusing intensive effort in a few small areas.This should be combined with great efforts to preserve all relatively undisturbed areas.This is probably the last generation who will even have the option of protecting nativelandscapes, for the last remaining natural habitats are being threatened right nowacross the globe.

Another significant obstacle to woodland restoration has been the difficulty of finding anapproach which reconciles the seemingly conflicting needs of the various interests,especially between those who feel all 'natural' areas should be left in Mother Nature'shands and unmanaged and those who are concerned about historic landscapecharacter and aesthetic design. A real problem seems to lie in the idea that 'restoration'can be accomplished as a discreet project, analagous to an architectural reconstructionproject or a conventional landscape installation.

Such an approach by definition concentrates site disturbance, involving removal of allvegetation at once before initiating replanting and stabilization. A large project, whichincludes architectural reconstruction, may span several seasons, during which timenearly all valued wildlife is displaced from a site. An area which is a temporary restingsite for migratory warblers may be irreplaceable in a vast urban wasteland. Even aproject affecting only a portion of such a site may deny critical habitat to birds whocannot wait out a one or two year hiatus.

Struggling natural vegetation would be similarly impacted. When forest restoration isviewed in the spirit of a capital project, the sheer amount of work undertaken becomes asevere stress to fragile remnant systems. Large-scale grading operations, extensive soilreworking, and massive planting efforts are, in this perspective, sources of disturbanceand should be undertaken only where the landscape is in collapse, completelyoverwhelmed by knotweed, or with extensive and severe erosion. Similarly, where thevegetation is a mix of desirable species and pests, complete elimination of all invasivesat once may actually open up the landscape so much that a reinvasion, perhaps evengreater in scale, is invited.

A common approach to solve these problems is fragmenting a project into smallerpieces. However, though this confines damage to more limited areas at one time, it doesnot address the fact that this is simply a stressful way of working, and antithetical toestablishing healthier, more self-sustaining natural systems. The discreet design and


construction phase, under the tight control of the landscape architect, completed in onefell swoop, is simply not effective or even acceptable in the forest.

The recommended alternative involves incremental implementation and seeks toachieve restoration in discrete phases, which represent levels of health of the system,instead of area-by-area project completion. An important key to this approach torestoration is the principle of "minimal intervention", that is, taking only those actionswhich are necessary to counteract disturbance, but also taking no actions which mayinhibit the natural processes of restoration.

Recommendations made by foresters and horticulturalists often are very inappropriate inwoodland areas. Every effort should be made to avoid unnecessary soil disturbance,such as grubbing and rototilling. These methods may be appropriate to renovating ahorticultural bed planting, but are not suited to woodlands. If the surface is presentlystable, even if supporting only exotic invasives, beneath the soil there are roots ofnumerous different plants often from a great distance away. Tree roots, for example, arecompletely opportunistic, seeking any favorable ground, and easily extend thirty or morefeet beyond the furthest reach of their branches. Grubbing and rototilling also disruptsfragile microorganisms and may impact the mycorrhyzae on which good forest growthdepends.

The directive to thin canopy in order to stimulate shrub growth is almost alwaysinappropriate in woodlands. No urban of the woodlands yet has anywhere near thecanopy cover of a typical healthy native forest in the region ; nor is a forest a place tofavor specimen shrubs or specimen trees, for that matter. The round canopy of an opengrown specimen is not the forest ideal, but reflects a gardener's or horticulturalist's goalinstead. If this forest were a vast expansive, unbroken, and undisturbed tract, thencreating openings and some canopy thinning would greatly diversify the habitat andfavor desirable shrubs and herbaceous growth as well as canopy reproduction. Buturban woodlands are, instead, fragmented and disturbed, with a discontinuous canopy.Successional species, such as black cherry, black locust, and mulberry, often prevailand it is these species, as well as invasives, which would be favored by thinning, not themore desirable mast species of oak, hickory, and beech.

Critically ill people in need of surgery often must wait until they have recoveredacceptably to be strong enough to face the hardships of surgery. An analagous situationis faced in urban woodlands. The 'surgery' these landscapes require -- rebuilding theinfrastructure -- will be stressful. New paths are usually needed, drainage must becontrolled. These activities, while stressful, cannot be avoided if the landscapes are tobe utilized without damage by park visitors. But before this is undertaken, thewoodlands' recovery must be initiated.

At the outset, two management priorities are recommended for the forest managementteam. First, exotics removal concentrating in those areas where they are invading andbecoming established, rather than in areas where they are fully entrenched. Second,erosion control should focus on stabilizing all exposed bare soil. The team should be


trained in mechanical control of exotics and it is advisable if one team member is trainedand licensed in the application of herbicides, although this is not absolutely necessary.At the same time, the team will require training in conventional planting as well asstabilization techniques, including long straw, jute matting, and dead stout stakes, andusing bioengineering techniques of live stakes, fascines, and brush layering to establishnew plants. Erosion control and exotics control should be the only major priorities until amuch greater degree of stability is achieved.

Where new pathways are proposed, they should be laid out for evaluation and modifiedin the field as necessary. Large trees along the route may benefit from root pruning aswell a prophylactic canopy pruning to compensate for projected root losses.

The margins of all existing and proposed pathways and other features to bereconstructed should be the special focus of exotics control to reduce the presence ofinvasives available for recolonizing the site. Restabilization of all severely eroded areasshould be given the highest priority. Once bare ground is exposed, deteriorationtypically accelerates rapidly.

Stabilization and exotics control should precede planting for restore diversity, althoughsome planting, of course, will be integral to stabilization.


GROUND STABILIZATION

Before we can address the issue of restoring vegetation, we must insure that the groundon which the plants are growing is stable. Frequently a manager will want to improve anobviously deteriorating habitat without being aware that serious trampling or stormwaterdamage is occurring and must be controlled first for restoration to be effective. Soildisturbance is one of the most common sources of stress to urban wildlands andfrequently precedes invasion by exotic species. The problems encountered typicallyinclude soil loss or erosion, excess fill or the addition of soil, soil compaction, or acombination of the above. In all cases, it is important to address the problems of soilstabilization before attempting to manage the vegetation. There are many sources ofground disturbance which characterize landscapes in the developed corridor.


STORMWATER MANAGEMENT

Erosion from excessive runoff represents one of the most ubiquitous and costly sourcesof damage to urban wildlands. A single outfall from a storm sewer discharged on a steepslope can cut a deep gully very rapidly. Many of the stormwater problems observed willoriginate off site, beyond the boundaries of immediate ownership. People often feelhelpless to deal with stormwater, in part because it may require complicated negotiationwith adjacent landholders and public regulatory agencies. However, stormwater shouldbe treated as close to the source as possible, that is, not by riprapping the banks of thestream in the park but rather on the property of the development where the excess runoffbegins. This will require a willingness to confront problems off-site, effective negotiation,and constant monitoring. Enforcement and upgrading of local regulations should alsobe pursued by land managers. Sadly, many stormwater management regulations areapplied only to new development and are non-existent and unenforced in urban areas,where all runoff is simply shunted to the existing storm sewer, which is, at best, enlargedwhen it fails to function. Where regulations apply, detention basins are often used toreduce peak discharges by holding water and releasing it more slowly; however,problems can still result if the outfall is improperly sized and located. Stormwater designoften focuses on flooding only and the outlet structure may not provide any detention ofthe smaller but very frequent one or two-year storm which travels through the pipe athigh velocities. A graduated outlet structure sized to maintain flows which are no higherthan when they would occur if the site were covered with a dense meadow, or evenforest for a range of storms, from the two-year to the 1OO-year storm, will provide a muchgreater degree of protection.

Beyond the visible damage to slopes and stream channels, the natural hydrologicregimen is also altered by poor stormwater management. Water that previouslyinfiltrated into the soil now runs off, failing to replenish groundwater. Streams whichonce ran year round became flashier, subject to periods of flooding and periods ofdrying out. Dropping groundwater levels, which reduce the base flow of streams, mayalso severely impact vegetation. Many mesic species, such as beech and white oak, aredependent upon closeness to water table to weather times of drought, and cannotsurvive continued lowered water table conditions. If adequate levels of recharge are notsustained over time even larger changes in vegetation are likely.

Correcting these problems goes well beyond the scope of this manual, however, severalgeneral recommendations are appropriate.

Stormwater management is best addressed over the entire watershed. Thesimplest approach usually is to seek multiple solutions at different points, rather than asingle cure-all at the point of discharge.


Look first for solutions which most closely mimic nature's solutions· thosewill likely maximize opportunities for recharge. Permeable surfaces such asporous asphalt paving over shallow infiltration beds are an excellent way to achieverecharge as well as detention wherever long-term clogging of the lot can be controlled.Upland retention ponds can also be designed to provide both open water and marshhabitats while effecting recharge when water levels are high. Both these technologiesprovide significant improvement of water quality of urban runoff and serve to limitcontamination of both ground and surface water. Sometimes simply altering themanagement of landscapes can effect substantial reductions in run-off. Turf areas, wheneven only gently sloped, shed water nearly as rapidly as pavement. Conversion of all orpart of the lawn to tall grass and wildflower meadow can provide friction to slow runoffvelocities and a root system which effects higher levels of infiltration. Tall grass can alsoserve to inhibit trampling or help confine walking to trails and turf areas. If retainingrunoff and maximizing recharge are vigorously pursued in the uplands the problems oferosion in lowland areas will become more manageable. No site is too small; theprocess is cumulative. Each infiltration trench adds up.

Solutions to the problems of lowland areas should also seek to mimic analagous naturalsituations. In the course of restorations, typical actions include taking a stream out ofpipe rather than put the stream into a pipe, reestablishing a natural meandering channelrather than channelizing a stream and planting trees along the stream corridor ratherthan removing them.

Occasionally some disturbance to wetlands will be unavoidable and thisshould, of course, be mitigated to the greatest extent feasible, however itshould be recognized that 'created' wetlands are not comparable tonatural wetlands and should not be 'traded'. The regulatory processshould not be used to facilitate this attitude.

One of the most important roles a designer can play today is to solve site problems in amanner that does not take such a terrible toll on our remaining natural areas. Thenatural hydrology of each site should be respected, that is it should be preserved in alllowland and floodplain areas and it should be restored where the system has beenfragmented. Increases in runoff which are generated by development should behandled in the uplands where the development occurs.

There are several excellent publications which describe the design and construction ofmarsh and open water detention ponds available from the Maryland Department of theEnvironment Sediment and Stormwater Division, Tawes State Office Building D-2Annapolis MD 21401 :

#6 Guidelines for Constructing Wetland Stormwater Basins (March 1987).#7 Wetland Basins for Stormwater Treatment: Discussion & Background (March

1987).#11 Feasibility & Design of Wet Ponds to Achieye Water Quality Control (Bruce

Harrington, July 1986).


Also available from the same department are several publications describing a variety ofinfiltration practices including porous paving and the results of their pollutant modellingprograms to date:

#3 "Results of the State of Maryland Infiltration Practices Survey" (Kenneth Pesyl &Paul Clement, August 1987)

#10 "Infiltration as a Stormwater Management Component (H. Earl Shaver, July1986).

#15 Standards & Specifications for Infiltration Practices (February 1984).

Also of interest concerning porous paving and other infiltration practises is ChesapeakeBay Research/Demonstration Project Summaries July 1, 1984 - June 30, 1987 VirginiaDepartment of Conservation & Historic Resources, Division of Soil & WaterConservation.

There is always concern about the pollutant load when dealing with stormwater and theextent to which either ground or surface waters might be contaminated by differentmodes of handling runoff. The Nationwide Urban Runoff Program is the mostcomprehensive evaluation being undertaken currently. An Executive Summary of theResults of the Nationwide Urban Runoff Program PB 84-185545 December 1983 waspublished by the Environmental Protection Agency, Office of Water Program Operationsand is available from the National Technical Information Service, U.S. Department ofCommerce.

Beyond reducing runoff as a first priority, there is also the problem ofrestoring areas which have been eroded and handling runoff on site whichcannot be reduced at the source. The goal is to divert small amounts of the loadover and over, to effect a substantial cumulative reduction in runoff. This is the oppositeof conventional drainage practices in the past which concentrated runoff. Water can beimpounded over a variety of landscape types for short periods to reduce the rate andamount of runoff and to effect greater recharge. There are several techniques which canbe used, including: temporary shallow impoundments, shallow terraced impoundments,low earthen berms with imfiltration trech, check dams in gullies, check logs on slopes,and path reinforcements.

Woodland slopes can be better protected using temporary shallow Impoundmentsand low earthern berms with infiltration trenches to retain small amounts ofrunoff on adjacent meadow and lawn areas. Shallow terraced impoundments canhelp control flows along sloped sites. Check dams can be constructed in gullies toreduce velocities and redeposit sediment. Where only minor control is required, checklogs on slopes can be be very useful.

Stable, healthy vegetation, of course, is the most desirable erosion control and, as ageneral rule, more vegetation is better than less and diversity is usually preferred. It isthe first line of defense. All areas of bare soil in the forest should be revegetatedalthough the vegetation is comprised primarily of stratified woody plants rather than amore uniform ground cover, or turf, or shrub beds.


Case Study: Runoff Recharged Through BasinsBeneath Porous Asphalt Parking Lots

At a new world headquarters for a major chemical company to be located adjacent to astream and beech forest, storm water recharge beds eliminated the need for aretention basin, preserving the natural setting of the site and saving enough land tobuild another building.The new headquarters building had already been designedwith a conventional storm water management system with runoff from impermeablesurfaces directed to a seven foot deep retention basin, which would have requiredexcavation of the stream bed and destruction of the adjacent lowland forest.Andropogon, with consulting engineers T.H. Cahill, designed a new system whererecharge beds "leak" storm water into subsoils via gravel filled basins locatedunderneath parking areas paved with porous asphalt.

I I

~ , IRunoff scenario directs storm water runoff to a large retention basin destroying stream and forest.

Recharge scenario directs all storm water runoff to recharge beds beneath the parking lots, preserving stream andforest, and allowing water to seep slowly into the ground.


Case Study: Runoff Recharged Through InfiltrationTrenches at Edge of Parking Lot

At an automobile dealership, located on a slope adjacent to a stream valley,uncontrolled stormwater from the parking area had eroded the hillside and wasdamaging the banks of the stream. The new owners, an oriental rug store, wanted amore appropriate businesss image, and were under community pressure to clean upan unsightly lot. Andropogon redesigned the parking to accomodate the same numberof cars, but removed unecesssary paving to create a landscaped setting for hebuilding. To control stormwater, a continuous infiltration trench was dug at the loweredge of the lot and backfilled with broken asphalt recycled from the demolishedpaving. The trench was topped with a layer of river gravel in order to provide anattractive appearance and areas newly released to soil, planted to grass andtrees.The recharge trench has been effective in containing all runoff from the site,during even peak rainstorms, and after 10 years is still working well.

'..

. :.. «mI'. .. ..

Before: Blacktop completely covers the site, sloping to the road without any provision for drainage.

After: Reorganized parking area with infiltration trench allows edges of lot to be landscaped.


----

Recharge beds are excavated to porous subgrade and covered with filter fabric. Clean uniformly graded, coarseaggregate is placed in the basin and later "choked" with fines and topped with porous asphalt paving.

Storm Water Recharge Beds

---'==---- Compacted----I

subgrade

Section: Showing recharge bed surfaced with porous asphalt. Stormwater can enter the basin in three ways, throughperforated pvc pipe which drain roof surface into beds, through porous asphalt paving and by an open gravel trenchat the edge of the parking lot which acts as a backup system if the porous asphalt becomes clogged


The recharge trench during construction, showing the broken asphalt infilland filter fabric linear to prevent finematerial moving up from the soil below and clogging the voids.

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,

Several years after construction, the vegetation is well established and the banks are stable with no signs of erosion.Storm water is recharged into the subsoil and percolates slowly into the stream.


THE NOT :So #.PGcitYPJlAL TALI:,

of ""I$I:·S MILL RUN

5

by Rolf SauerTo follow the tale simply apply,the numbered captions below to the numbers on the

illustration at left.1. '1'0 remedy parking overflow from nearby developments, make Port Royal Avenue (for

merly a country lane) into a four-lane arterial street. Add curb8 and street drains' toassure .that the now thousands of gallons of rain water will not filter into the ground,bur rather go directly into pipes. The word most often used to describe this work, evenwithin the Streets Department, is "abomination." Cost: Just under $1 million.

2. Allow high.density development near the park for maximum detrimental effect. Clearthe area of trees, fill in valleys, and direct all rain that falls on parking lots and roofsinto pipes. If community objects, cite historical architectural images that imply goodtaste, or say "you won't even see the building from the road." Get all streets and sewersfully designed before submitting them to the Planning Commission, so that rejection orrevisions are impossible. If community objections persist, pull out the old show·stopping "tax ratable" ploy, but be careful not to mention (or even consider) the in·creased public costs from traffic congestion, flooding; park destruction, minimaldeveloper assessments for public services, and the dimunition of the quality of life.

3. Tear up the park and put in steeply inclined pipes to increase velocity of flood waters.4. End job by dumping all this into tiny park streams, which will scour the banks .and send

tons of eroded debris downstream. Let the Park Commission take it from here, sincethey have a miniscule budget and now an uncontrollable torrent of water to boot.

5. Should things become unsightly, what with roads and bridges washing out, turn Wise'sMill Run into a concrete gutter, which both concentrates the water and maximizes itsdestructive velocity, sending eroded debris right into the Wissahickon. The word mootoften used to describe this work, from conservative city engineers all the way up to theManaging Director's Office, is "disastrous:' Cost: Just over $500,000.

6. Dump tons of eroded debris into Wissahickon Creek, so that the creek's width isr~duced to only 10 feet. The Wissahickon will then have to change its course.

7. In changing course, the opposite creek bank will collapse and large trees will fall intothe creek.

8. The creek will then start to meander, scouring the other side as well, endangering thestability of l<'orbidden Drive: The final irony of all this is that the sediment will becarried into the Schuylkill River, reducing its depth, and further cost the publicrecurrent expenses in dredging the harbor for ship passage. Our water quality will alsobe reduced (note that the city intake for the water we drink is just below theWissahickon on the Schuylkill).

This not so apocryphal tale is presently on view just above Valley Green along ForbiddenDrive. In introducing the capital budget, Mayor Green's wish that our streets should becleaned and our park grass cut seemed to pale before these more fundamental issues involving millions upon millions of taxpayers' dollars.

This satirical description of the impact of stormwatermismanagement from development located on the plateauabove a stream valley, on the forested urban park below,was published in a local newspaperThe Chestnut Hill Local, April 9, 1981.

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Case Study: Riprap Swale Transformed intoPlant and Animal Habitat

After construction of its world headquarters, Andropogon worked with Animal HealthProducts, a Smith-Kline Beekman company, and their site managers, to develop andimplement a 3-year landscape plan for the entire site. This plan focused on solvingproblems caused by mismanaged storm-water runoff, and on preserving, andenhancing, the unique pastoral charactor, and natural habitats of this 300 acre farm.

Before: Unable to carry the increased load of stormwater after development, existing turf swales were stabilized withunsightly rocks and riprap.

After: Rip rap was removed and swales regraded and treated as a meandering, intermittant, stream. Swale bankswere planted with emergents, native wetland grasses, and lowland trees and shrubs.


Techniques: Temporary Shallow Impoundment

Whenever there are open areas such as lawns or pavement, there are likely to beopportunities for impounding surface runoff. the most obvious choices for locating suchimpoundments are areas where standing water is found during and after a rainstormand where the existing level of impoundment can be easily increased to provide moreretention. Temporary shallow impoundments are essentially broad, shallow retention'puddles' created either by excavation or by the creation of a low berm to hold backwater a! the point of runoff. Downslope water movement will not be eliminated by thesemeasures, but it can be slowed and reduced. While no single impoundment will makethat great a diffference, numerous, small, basins throughout a site can make asignificant contribution. These shallow depresions can be maintained in a turf grassthat tolerates standing water for short periods, such as K31, or planted to a wetmeadow of ferns, sedges, rushes and native wetland grasses, or copses of native,lowland trees and shrubs. It is important that runoff does not carry high sediment loadsor these small basins will rapidly silt in, however, where surrounding areas areappropriately stabilized, siltation should not be a problem on upland sites.

CREATE SHALLOW TEMPORARVIMPOUNDMENTS BV REGRADINGGRASSED AREAS IN LOWTRAFFIC AREAS

Plan: Showing typical temporary shallow impoundment.

SHALLOW TEMPORARV

~R"ss .,,~'.,,~'.~~"~~:"'. .~F~ATE~ \ ...........-r-."""'=7~EH'"'...EUjEm".4 m•••••_••!._._.•-4ml""'...E...~;;;;;:a ""'-.....

GRASS SPILLWAV I ---.

Section: Showing typical temporary shallow impoundment.

-,


Techniques: Shallow Terraced Impoundments

Where a slope is long and shallow and largely open, a sequence of berms andinflitration trenches can be effective in slowing stormwater movement downslope andrecharging it into the ground. The number and spacing of these trenches should bedetermined on site, and depends on the degree of current erosion, the steepness ofthe slope and the amount of use. Soil from the trench should be used to build theberm, topsoil should be separated from subsoil and placed on top of the berm, andthe trench filled with gravel. The berms can be seeded and allowed to grow up into tallgrasses arid wildflowers, if it is desired to keep the hillside open, or planted tosuccessional woody species to form hedgerows. Whatever the landscape treatment,however, increasing the 'roughness' of the ground will slow movement of any waternot impounded.

RECHARGE TRENCHES

~-+- PLANTED BERMS

TERRACE

Plan: Showing typical shallow impoundment terrace.

PLANTED BERM

SHALLOW IMPOUNDMENTTERRACE

GRAVEL RECHARGE TRENCH

Section: ShOWing typical impoundment terrace.


Techniques: Low Earthen Berm withInfiltration Trench

An important level of protection from stormwater runoff can be provided for a woodedslope by the creation of a low earthen berm and infiltration trench, located between thedeveloped portions of the site (on the plateau) and the forested slopes. The berm willreduce the frequency and velocity of overslope water movement and provide limitedstormwater retention. It is critical that the berm be placed at right angles to the slope orit will cOi~'/ey water downslope. A trench can also be dug beyond the top of the slope,on the plateau or flatter area, and filled with gravel to create a linear soak pit.Sediment must be controlled or the trench will silt in rapidly. Soil from the trenchshould be used to build the berm. Topsoil should be separated from subsoil andplaced on the surface.The berm should be seeded and allowed to grow up intowildflowers and tall grasses or planted to ground cover to increase the 'roughness' ofthe ground and slow movement of any water not retained. Although only a smallvolume of runoff can be held and recharged in this manner at anyone site, if thesemeasures are employed continuously or nearly continuously along the slopesignificant protection can be achieved.

INFILTRATION TRENCHES

Plan: Showing low earthen berm with infiltration trench

Section: Showing low earthen berm with infiltration trench.

REGRADE TO FORM A RIMBERM WITH A LEVEL TOPOF NOT MORE THAN 18"HIGH

SURFACE IMPOUNDMENT

INFILTRATION TRENCHOF NOT MORE THAN2'-0" DEEP

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Techniques: Check Dams in Gullies

Where gullies have formed, low wooden check dams can be built from tree trunksfound on the site and used to reduce the velocity of runofff and encourage thedeposition of sediment within the gully. These dams should be small and located atfrequent intervals. Their purpose is to reduce the velocity of stormwater which in turnwill reduce the capacity of this water to erode. At the same time the check damsencourage the deposition of sediment in the runoff, all along the length of the gully,rather than at the bottom of the slope. It is important to acknowledge, however, thatcomplete gully restoration cannot take place until the quantity stormwater received hasbeen significantly reduced. These check dams must be small enough to permit a flowof water over the dam or new channels will be cut at the sides. These dams must alsobe located so that the top elevation of the downstream dam is no lower than the bottomof the upstream dam or scour just below each dam will occur. Check dams made fromwood found on the site do not typically last more than three to four years and shouldbe rebuilt as needed.

ERODED SWALE~

LOG CHECK DAMS

EACH DAM SHOULD BE SPACED TO BACK WATER UP TOTHE BASE OF THE HIGHER DAM - INCREASED EROSION OFGULLY WILL OCCUR IF THIS IS NOT DONE

Long Section: Showing gully with check dams.

~~. ·"'''''· ~;:·l.,:~;ftj~~~·;r::~;t;};';':.,Ii ';~!~'"

~~~:E:s:i '~" ~'''i~''~' .;::'!"" THE HEIGHT OF THE CHECK DAM,. SHOULD NOT BE MORE THAN HALF

THE DEPTH OF THE GULLY ORGREATER THAN 2"-0"

Cross Section: Showing gully with check dam.


Techniques: Check Logs on Slopes

Where no gullying has occurred, but bare soil and limited erosion are evident,a series of check logs staked along the contours can help control erosion. These lowbarriers will reduce the velocity of runoff and may retain water long enough to providesome recharge into the ground as well. By trapping both water and sediment, theyencourage natural regeneration and provide good sites for replanting, particularly theshrub and understory layers of a forest. The number and spacing of these check logsshould be determined in the field depending on the steepness of the slope and thedegree of erosion. Slope check logs can also be used as reinforcement, on thedownslope side of pathways that are channeling stormwater and currently conveyingrunoff to the slope.

. :::::: !~ljlli.

NEW SOIL BEHIND 'CHECK LOGS' - // ."

'CHECK LOGS' PLACED ALONG / ~CONTOURS TO SLOW FLOW OF WATER / 1

ST AKES TO SECURE LOG

Section: Showing side of eroded forested slope with new check logs placed along the contours.


Perspective: Showing Placement of check logs on steep, forested slope.


NEW COMPACTED FILL LAID IN LIFTS

Case Study: Restoration of a Forested Stream Valley

When failure of a city reservoir accidentally released 150 million gallons of waterinto a stream valley in Philadelphia's Fairmount park, it severely damaged the streambanks and stream bed, as well as the mature forest, and important historic sitesadjacent. Andropogon assessed the damage to both natural habitats and culturalartifacts, and provided a phased plan for restoration of the stream channel and thesurrounding lowland forest.

Before: Water from the reservoir scoured out the streambed,in some cases dropping the original level by 6 feet ormore. The deepened channel resulted in a lowered watertable which was stressing the older trees during summerdroughts.

LINE OF ORIGINAL STREAMBEDREESTABLISHED WITH FILL

ERODED STREAMBED

GEOTEXTILE FABRIC3\DUMPED ROCK FILL

FILL MATERIAL TO BE SIMILARIN TEXTURE AND PERMEABllITVTO ORIGINAL SOIL

After: Streambed reestablished at original level with backfill of the same density, texture and porosity. Small rockdams at frequent intervals prevent movement of backfill material.


Techniques: Gully Stabilization

Before any physical restoration of the site is attempted, every effort should be made toreduce the volume of runoff as described in the stormwater section of this manual.If not all the runoff can be accommodated elsewhere, the amount remaining must becalculated so that the proposed solution can handle the necessary volumes. In thisexample, a corrugated pipe is installed to carry the runoff down the steep slope directlyto the receiving stream and has been sized to handle the 50-year storm. Larger butless frequent storm flows are assumed to flow overland downslope.The gully backfillmaterial should be as close as possible in character to the surrounding soil and mustbe compacted in 6" lifts to densities which approximate adjacent soils. If too loose, thesoil will tend to settle and may continue to convey water outside the pope and erodegradually. Note too that a gentle swale configuration is maintained to handle overflowstormwater. Disturbance of adjacent vegetation and uneroded areas must be avoidedduring reconstruction. The site should be fenced before any work activity is initiated. Aqualified arborist should be used for any pruning or tree removal. It is especiallyimportant to ensure that adjacent vegetation isn't damaged by taking large trees downin sections. If work is initiated at the bottom of the slope, the fill can be added in liftsand compacted by the construction vehicles themselves, as they use the refilled areasfor access to upper portions of the gully. Care must be taken, however, not to crush thepipe.Temporary sediment and erosion controls on the work site are mandatory andmay include silt fencing, hay bales, and temporary drainage swales and detentionbasins.

WIDTH OF ~WA)..f 18" 12.'

JJJ.TE MATTINo- t---..JCOMFACTED flU-!-----J

Section: Illustrating techniques of gully stabilization


Photograph:lllustrating the problems of a gully. Not only are roots exposed and trees toppled, but the velocity andvolume of runoff have caused a deep ravine. This ravine is actually deeper than water table at some seasons andestablishes a new hydraulic gradient back from the gully across the entire slope. Groundwater is drained away andwater taable levels permanently lowered. Sensitive species like beech and oak will gradually die off and be replacedby earlier successional species such as ash and maple which are more tolerant of fluctuating, flashier conditionsunless nearly exotics overwhelm this disturbed site.


EXCESS FILL

Urban wildlands are frequently subject to disposal of excess fill. There are a variety ofreasons for this; typically, development has already occurred on the flatter well-drainedsoils, leaving steeper slopes and wetlands in vegetation. As increasingly marginal landsare built upon, fill is used to even out the topography for easier construction. Despitewetlands legislation and regulations to limit construction on steep slopes, you can findhundreds of examples of filling throughout the region, often on sites too numerous andsmall to demand the attention of enforcement officials. Lots are casually enlarged androads widened by continuously pushing a little fill over the slope. Even when a legal fillproject is conducted, excessive fill and sedimentation off site is still routine. In addition tothe direct application of fill, there is a large amount of silt carried in uncontrolledstormwater. Excessive runoff from a storm culvert or road which dead-ends in a parkmay bring large volumes of silt and debris, which may then erode the banks of a nowoverloaded stream channel, and later deposit the fill lower in the valley.

The impacts of this fill are severe, but may take years to be fully visible. Ground layervegetation is covered up and trees and shrubs may be damaged or pushed over byheavy equipment or the sheer weight of the fill. Vegetation which seems to be spared isoften also killed, slowly, by the presence of fill over root systems. Different tree speciesare tolerant of differing amounts of fill; oaks and beech, for example, are notoriouslysensitive and may be killed by just a few inches of soil. Box elder and sycamore areespecially tolerant and often survive under conditions that would kill other species.

Roots also respire and the added layer of soil inhibits the exchange of atmosphericgases that occur in the upper soil horizons. New roots can extend upward into the fillzone, but this may not be rapid enough to save the plant and will not occur if the fill hasbeen compacted. Toxic gases given off by the roots also accumulate beneath the fill.The weight of the fill may also be enough to compact the soil, further inhibiting plantrecovery. Soil piled against the trunk can also rot the bark and damage the root collar.The response of trees, for example, to excess fill over their roots is all too frequentlyvisible in new developments, where large trees have been spared the axe, but not thebulldozer. New home buyers are often unaware of what has occurred and are dismayedthree years later when their beautiful trees start to drop large limbs, dying in pieces untilthey have to be removed at considerable cost.

The new fill is usually very poor quality soil, low in organic matter and largely mineralsubsoil. This is a poor medium for renewal of the forest and a great place for invasivedisturbance vegetation. Frequently bits of exotic plants may have arrived with the fill.Almost any part of the Japanese knotweed, for example, including a sliver of root orpiece of stalk material, is capable of rooting to establish a new colony.

Where fill has been added to flat sites, the surface is often compacted by heavyequipment so densely that it is like concrete. Conversely, fill on a slope is almost alwaysvery loose, having been simply pushed over the edge. It erodes and slumps


continuously, making it almost impossible for new plants to become established on theever-shifting ground.

One of the most difficult questions to answer is whether or not to attempt to remove thefill, which can be a costly and disturbing event in itself. In most cases, even if the bulk ofthe fill cannot feasibly be removed, some regrading is almost always advisable.

The more recently the filling occurred, the more likely that with prompt removal theexisting vegetation can be saved, if it was not cleared or severely damaged during thefilling operation. It is advisable to pull some fill away from tree trunks to examine thecondition of the bark. Some species, such as sycamore, are more tolerant and willsurvive years under partial fill, sending numerous adventitious roots out from the buriedportion of the trunk. Others, like tulip poplar, are much more sensitive and may showsigns of bark rotting after only months of cover. If the trees still appear alive and vigorousand do not show signs of losing major limbs or broad areas of rotting bark, removal ofthe fill is strongly recommended. Substantial hand labor may be necessary to keep fromdamaging trees with heavy equipment. As close a grade as possible to the originaltopography should be reestablished. The regraded area should also be stabilizedimmediately.

The proper disposal of the fill which is removed is important. Transport is costly andalmost anywhere the fill is disposed impacts natural habitats adversely. On site,however, the fill can often be reused to further restoration efforts to refill eroded gullies,as described in the following section.

Overall Guidelines When Fill is Removed

If fill can be removed, regrade to original, or at least gentlest slope that can be achieved,without damaging roots of existing trees or disturbing other stable vegetation.

Hand work and raking may be necessary or use the smallest equipment feasible. Asmall dragline operated from the top of the slope may also be feasible. Even if there areno surviving trees, it may be desirable to achieve a shallower and more stable slope.Typically, a slope steeper than 3 to 1 of fill soils will be difficult to stabilize. In regrading,heavy equipment can be used if access is available, however, the lightest equipment ispreferable to minimize damage to the soil. Once the fill is removed, the ground shouldbe restabilized as soon as possible (see the guidelines for surface stabilization). Wherethere is inadequate vegetative cover, additional planting may be necessary, asdescribed in later sections.

If the fill cannot be removed, or too little can be removed to save existing vegetation, itmay be necessary to remove dead or dying trees along walkways or where they pose ahazard to people or to other areas of healthy vegetation. Otherwise, dead treas shouldbe left in place for their value to wildlife (see section on dead wood). Filled slopes are

often easily colonized by exotic invasives; therefore, it is likely that control of exotics willalso be required as described in later sections.


Overall Guidelines When Fill Is Left In Place

When fill is left behind it often causes long-term problems of vegetation management.There are, for example, numerous urban valleys with tons of construction rubble thatyears after deposition still support only mugwort, common reed, and a few isolatedweedy trees. The fill material is usually of very poor composition and may beexcessively drained or very poorly drained or both, in patches. The costly addition of alayer of topsoil rarely addresses the real problems though may support a stand of turf fora few years before it starts to deteriorate. As an alternative to simply capping the sitewith topsoil more detailed investigations of what comprises the fill are usuallynecessary. The upper three feel of soil usually require some level of reworking whichmay include mixing in various missing soil components such as sand where the materialis too clayey, or organic matter where too little is present or powdered rock where thereis no mineral component.

Sometimes the soil is so poor that there is a fine line between fill and debris or trashdisposal, which may create more difficult management problems. Junked automobilesand old refrigerators can and should be removed wherever possible without unduedisturbance. Indeed, all trash cleanup feasible should be undertaken. Any rubbish leftbehind is only incentive for further dumping and as with grafitti, the most effectiveremoval is that immediately after the incident has occurred. New dump sites ifunattended to may rapidly develop into serious problems and illegal disposal of toxicmaterials is occurring increasingly often where such activities appear to be tolerated orunnoticed. However, in places, construction rubble may be so mixed in with the fill soilthat separation and removal of the rubble component may be extremely difficult andremoval of the entire layer too extreme. Such sites should not be expected to supportmore than the toughest plant communities, at least at the outset. The presence ofcontinuous cover alone will ameliorate extremely bad conditions by loosening soil andadding organic matter over time. Native plants which are volunteering on such sitesshould be enhanced and typically include sycamore, cottonwood, willow, cherry, blacklocust, red mulberry, box-elder, white ash, etc. Not until these species arewell-established and have had time to modify the site somewhat should majorrestoration be considered and the goals should be tempered with an awareness of howlong it has taken to achieve a satisfactory level of recovery.


Case Study: Restoration of a Steep Forested Slope

For a 30 acre school campus with severe environmental damage and acute accessproblems, Andropogon prepared a landscape reclaimation program in concert witha site development plan. Construction of a long, shallow, ramp down the hillsidecreated new access to the athletic facilities on the other side of the valley and allowedthe highly eroded slopes to be regraded and the ground stabilized. The haphazardparking area on the plateau was reorganized and drained to soak pits to preventoverslope runoff. Overslope dumping was restricted.

Before: Damaged by runoff from parking areas and building roofs as well as dumping, the steep forested slopes werebadly eroded and deep channels had formed on the hillside. Aconcrete stairway, linking the upper and lower fieldshad been undermined when the slope subsided.

After: A new acess ramp on regraded and stabilized slopes connected upper and lower portions of the site.A newly planted meadow of native grasses was also seeded with native, early successional trees and shrubs toaccelerate the return to forest.

Success Under Stress: Managing & Restoring the Metrororest 39

USER ACTIVITES WHICH DAMAGE LANDSCAPES

Innappropriate behavior abounds in the urban wildlands both intentional andinadvertent. Though often very problematic, it is a testament ot the important andexhilarating sense of freedom people experience in parks and other natural areas. Theprimary activities which directly damage vegetation and disturb the soil surface includethe off-trail use of bicycles and vehicles and trampling.

Off-Trail Use of Bicycles & Other Vehicles

The off-trail use of bicycles, motorcycles, and all terrain vehicles often goes unnotices.Enforcement is very difficult, since they are not easily pursued except by another off-trailvehicle which, in turn, also damages vegetation. Bicyclists also have a place in a parksystem, for example, and often feel strongly that this includes the wooded sites, whetheror not they are aware of the damage they cause.

Where off-trail vehicular use occurs, it must be controlled immediately. In park systems aspecial task force should be appointed to develop a program to control illegal use. Theeffort should be initiated quickly and widely publicized. Restrictions should bedelineated clearly in all signage and park guide materials. The cooperation of organizedgroups should be sought and it is possible likely that meeting the needs of cyclistselsewhere in the park will be integral to effective negotiation. 'Hot' spots for ilegal useshould be targeted for extra security personnel during likely periods of high use.

Trampling

Controlling trampling would often make the single greatest improvement to the health ofwoodlands. This problem is especially severe because remnant forests often occur onsteep terrain or poor soils which are easily eroded or compacted.

With the expansion of development, shrinking wildlands are subject to ever-increasinguse. Even when there is a path system, many users deliberately avoid the paths in orderto have privacy for their activity or simply to experience a sense of greater wildness. Aground plane survey of Central Park conducted in 1982 revealed that over one quarterof the non-turf areas was bare ground, nearly all of it due to trampling or wheeledvehicles. Obviously, the first action to be taken is to determine the cause of tramplingand attempt to correct it. In some cases, the problem is lack of enforcement, a failure tocontrol off-trail use of dirt bikes, for example. This requires a concerted effort to regaincontrol of the park, and is essential if stable landscapes are desired and more costlylong-term problems are to be avoided. The restoration effort itself will bring additionalpersonnel to the park who serve as a continuous presence in the area, monitoringactivities and educating and, augmenting any security forces.

In other areas, trampling may simply indicates the lack of an adequate trail system or the


need to redesign the existing trails. Long-term management concerns must be includedin the design process or the new path will only relocate existing problems. Walkers willtypically bypass muddy or poorly drained stretches of pathway. Wherever it is desirableto close a trail, it is also important to remove it by restabilizing the soil and replanting. Itthey remain visible, they will attract a measure of use.

The decline of the landscape following trampling is a familiar scenario: it begins withdamage to herbaceous and small woody vegetation. Once exposed, a trampled trailoften is well used, and becomes in itself an incentive to further trampling. Often themaintenance of the original paths has been long deferred, which now have deteriorated.In many places, a desire line is often hard to distinguish from an original path. Until thepaths are rebuilt, it is unreasonable to expect the visitor to keep to them. In such a case,restoration of the path infrastructure should be given the highest priority and shouldprecede major replanting efforts.

While this report cannot deal extensively with the design of paths, several generalguidelines are offerred.

Overall Guidelines for Paths

A path is a balancing act: it offers protection for the ground surface as wellas a means to confine pedestrian or vehicular use; but it is also a sourceof disturbance. Opening a new trail should be undertaken with great care and withrecognition that it will have long-term impacts on the landscape and of the maintenancecommitment which is entailed. Nearly all paths in urban wildlands are undermaintainedand becomes continuous sources of stormwater damage, trash, and exotics. Oftendeterioration proceeds so far that outlaw trails are indistinguishable from once pavedpaths. All trails must be monitored and repaired on a periodic basis, adequate to restrictoff site damage.

The path surface must be adequate to carry the level of traffic it serves. Adirt trail which is clearly delineated is not eroding and stays dry enough year round, isadequate only in rural areas in areas with light use and no evidence of off-trail use.Periodic gravelling may be necessary with more moderate use. Where use is heaviest, apaved surface is typically required. Over time, the condition of the trail itself will illustratethe need for a more durable surface or better care.

A hierarchical trail system is often most useful with a main trail accessible to vehicles formaintenance and security purposes as well as to wheelchairs, a secondary trail systemfor pedestrians only, and a sequence of single-file adventure trails. The latter permitaccess to special places which walkers consistently favor such as an overlook or pondedge where a larger trail would be inappropriate. Ideally these trails should not look likepaths at all but simply be comprised of large stepping stones or wooden rounds whichappear like bedrock or smooth stumps yet control ambient trampling.

Bare soil is not an acceptable path surface for an urban park. All bare-earth, desire-line


trails should be eradicated and revegetated and all areas of bare soil should berestabilized. When bare soil is visible anywhere, trampling is undertaken far morecasually than when paths are well maintained and erosion well controlled.

The role of vegetation In Influencing visitor movement should berecognized. One of the most difficult aspects of trampling is that much of it isdeliberate. People often are attempting to find seclusion in the vegetaiton, for privateactivities, or simply for the sake of feeling removed from civilization. At other times,people want only to achieve greater intimacy with the landscape, to come closer to thewater's edge, for example.

A more subtle aspect of erosion has to do with the psychology of trampling and the kindsof spaces that are provided by the vegetation. Wherever privacy is desired, dense shrubor shrub-form vegetation is sought. Brushy vegetation close to the pathway, rather thanconfining the walker, actually may serve as an incentive to leave the path. The roundbushy, newly planted shrubs seem to discourage trampling for awhile, but once theybecome head high and serve as a visual screen they attract those who wish to hidebehind them and the decline begins. When one site, for example, is pounded intooblivion, it is abandoned in favor of another site, until the former site recovers and isonce again used. In contrast, the more open character of the mature forest areasactually affords less cover and is less trampled by those seeking shelter than sites withmore privacy.

Most forest management recommendations urge thinning of the woodland canopy, inorder to stimulate dense shrub and understory growth. However, this approach posesmajor problems in woodland areas of metroforest. Where invasive exotic vegetation isestablished, openings in the canopy are likely to lead to rampant growth of disturbancespecies, rather than favoring more diverse native vegetation. Secondly, more brushyundergrowth may actually encourage, rather than discourage, trampling by increasingcover for private activities. In a mature native forest, shrub and understory growth istypically relatively sparse, comprised of open-branching spicebush and maple-leafviburnum, as well as leggy sassafras and dogwood. This more open character in thewoodlands would provide both greater visibility and better security. Dense, round shrubmounds should, instead, be confined to planting beds in turf areas, where security isless problematic and plantings more easily replaced.

There are several excellent trail maintenance handbooks available including:

Trail Building & Maintenance, 2nd edition. Robert D. Proudman & Reuben Rajala. 1981.Appalachian Mountain Club (5 Joy Street, Boston MA 02108; telephone:617-523-0636).

Trail Design. Construction, & Maintenance. William Birchard, Jr. & Robert D. Proudman.The Appalachian Trail Stewardship Series. 1981. Appalachian Trail Conference (P.O.Box 236 Harpers Ferry WV 25425; telephone: 304-535-6331).


A pocket size manual is also available: Appalachian Trail Fjeldbook - a Self-Help Guidefor Trail Maintenance. William Birchard, Jr. & Robert D. Proudman. The AppalachianTrail Stewardship Series.1982.Trails Manual - EQuestrian Trails. Charles Vogel. 1982. Equestrian Trails Inc. (13376Sayre Street, P.O. Box 44135 Sylmar CA 91342).

These manuals are geared to larger wilder areas than many of those found in moreurban areas, but the techniques are still applicable, especially where paths are largelyunpaved. There is also a sequence of English trail manuals designed for volunteerconservation corps. The series includes numerous topics illustrating the verysophisticated level of maintenance which has sustained a public and private trailnetwork which is in places centuries old. These handbooks are published by the BritishTrust for Conservation Volunteers, 36 St. Mary's Street, Wallingford, Oxfordshire OX10o EU; telephone: 0491-39766. Compiled by Alan Brooks. The Practical ConservationHandbooks were revised in 1982 by Elizabeth Agate. Titles include: Waterways &Wetlands and Footpaths.


SOIL COMPACTION

Soil compaction can be a very insidious problem, largely because its effects are oftenunderestimated. Any time there is visible soil compaction, there has also been damageto vegetation. Herbaceous vegetation may be killed outright. In heavily used areas,shrubs and small trees may also be trampled to death. However, even trees not directlydamaged above ground may have sustained damage in the root zone (which typicallyextends well beyond the reach of the branches). EXisting roots can be crushed and thesoil may now be too tight for new roots to grow. In general, an ideal soil would bearound 50% void space and of that space 50% would be air and 50% water. A compactsoil typically has too little of both, lacking water and oxygen in the root zone foradequate respiration and growth. Not only are existing plants damaged, but the growthof new plantings can be severely restricted. A great place to observe this phenomenonis on new construction sites, where heavy grading equipment has been used in areasaround the building, and were later landscaped without adequate soil restoration. Newtrees planted often simply fail to thrive. They decline slowly, becoming more mishapenand feeble over time, necessitating frequent replacement.

Where compaction has occurred, it is important to repair the site as quicklyas possible or the compacted surface will continue to serve as a barrier toroot growth, inhibit the exchange of atmospheric gases, and restrict theinfiltration of water. Plants improve soil by adding organic matter and by looseningcompacted layers. Without vegetative cover, no organic matter is added and rainsplashaction alone, without further trampling, will increase compaction. In combination withair-borne pollutants, an impermeable surface or crust is formed, which reduces theinfiltration of water and inhibits air circulation, building up harmful levels of carbondioxide. The compacted zone must be broken up. There will be few, if any, roots in thislayer so no damage to healthy roots is likely if care is taken using a hand rake. Theaddition of organic matter is nearly always important and may be as simple as addingleaves from nearby. Straw mulch as well as jute or matting is usually the necessary tostabilize the surface until new plants are adequately established. If the mat is thencovered with leaves and light brush, all traces of both soil and the repair work can bedisguised.

Where continued compaction is unavoidable, it may also be advisable tomodify the soil structure to make it less compactible. Where the soil isexcessively clayey or silty, the addition of coarse material can make the soilless proneto compaction. Sand is frequently added, sometimes in proportions of up to 30%. Thispractice also improves drainage which is impeded by heavy soils; however, this mayalso make the soil excessively drained during periods of drought and therefore theamount added should be carefUlly evaluated. Because water movement is so restrictedin a heavy soil, in extended dry periods, this soil is also droughty because moisture isnot conveyed upward from groundwater. In some area a fly ash product is used in lieu ofsand. The fly ash is sintered; that is, heat treated to render it inert and to improve itstexture. Another product that may prove very useful is expanded shale or expanded


slate which is also heat treated to make it quite porous. Because this stone product isporous, it absorbs moisture -- up to 10% or more with expanded shale and appears toimprove moisture retention which would be a significant advantage over sand.

Another method which has been proposed for combating the problems of soilcompaction entails mimicking the function of the rotting roots of dead trees. After a treedies, the decomposing roots leave long continuous channels which are like pipes in theupper soil horizons, conveying water, nutrients, and gases downward and serving tocounteract compaction. Several researchers have proposed driving numerous stakesinto the ground around large trees as an alternative to reworking the soil extensivelywhich would damage existing root systems. Obviously this would be costly to implementover a very large area but might be ideal for selected sites with important specimens.Combined with breaking up the zone of surface compaction described earlier, the use ofsoil stakes should be evaluated further.

The demand for composted leaves for renovation efforts always exceeds the supply andwill surely grow once woodland restoration begins. In many areas of the woodlands theimportation of large quantities of topsoil may be far more costly than adding and mixingsoil amendments such a manure, humus, leaf mold, compost, dredge spoil, sand, andexpanded slate with existing compacted subsoils.

Powdered rock dust is also worth considering as an alternative to synthetic mineralfertilizers. The depth of fill often prevesnts the soil from gaining nutrients from the actionof weathering of bedrock. It should be evaluated in the woodlands as a mineralamendment which can be sprinkled on top of the soil or worked into the soil whenstabilization is undertaken.

Large boulders are extremely valuable and should never be simply disposed of. Theycan be used as aesthetically pleasing rip-rap and to create artificial 'bedrock' surfacesas part of indian-file trails and stream channels, and to provide access to specialfeatures such as the water's edge.

Where bare ground has been so eroded that the addition of soil is required, it is usuallynot necessary to incorporate new material deeply into the existing soil. Where thesurface has been compacted, however, it is mandatory to break up the compacted layercompletely and stabilize the surface with jute and long straw. Otherwise it serves asan impermeable membrane between old and new soil, preventing roots from growingupward into the new soil and inhibiting water infiltration from above; the new soil andnew plantings will never properly knit with the existing soil, leaving the site permanentlyless stable than was the goal. Because there are no viable roots in tightly packed soil,the risk of disturbance is very low. This layer may only be inches thick, and there israrely a need to go deeper. Hand excavation and raking is the most appropriate methodfor this task.

At this point, organic matter and other soil amendments can be added, and if necessaryadditional topsoil to reestablish the pre-existing grade. In other situations, mulch and


seed, sod or groundcover plantings would complete renovation. However, this is not thecase in the woodlands. Because of the heavy canopy, vegetative recovery is very slow.Reproduction by seed is negligible and vegetatively established plants may take severalyears to provide adequate cover under dense shade. Therefore, additional protection inthe form of an erosion-control blanket is usually beneficial. A three-inch layer of longstraw (that is, uncut rather than shredded) covered with jute matting tacked with woodenstakes is a completely organic treatment which provides erosion control as well as ameasure of protection from damage should some trampling occur. Jute matting alone isnot adequate. When the soil surface is treated in this fashion, uncomposted leaves maybe used as organic amendment without worrying that they will induce slippage of thenew soil. Both the leaves and the matting with soil will decompose in place, providingadditional nutrients. This technique is durable enough that the surface will withstandsignificant levels of runoff and disturbance and can be effectively implemented beforecomplete construction of drainage structures.

Exotics control should be carried out concurrently and incrementally -- a kind ofcontinuous attack policy. Any area cleared should be replanted immediately, with astraw and jute matting, wherever existing native cover is inadequate to close the gap ina single growing season. The rate at which ground should be opened and replantedshould be determined by what can be adequately maintained in subsequent years.


Case Study: Rehabilitation of Bare Compacted Soil

A familar sight in urban woodlands today - bare, compacted, soil from uncontrolledtrampling. This area, part of the Richmond National battlefield Park in Virginia, wasrestored as part of a demonstration project sponsored by the National park Serviceand given by Robbin Sotir of Soil Bioengineering in concert with Andropogon.Soil rehabiltation was followed by surface protection and replanting with live stakes.Where the shade from the forest canopy is too great for plants used in live staking,other replanting techniques such as the use of balled and bagged, bareroot andcontainer material or shrub mats dug from the site, would also be effective.

Before: Uncontrolled trampling has exposed tree roots and destroyed shrub and herbaceous layers, effectivelyhalting all reproduction of native species.

After: Showing the last step in the restoration process. Jute mating has been laid over prepared ground to hold thesurface, and held in place with diagonally split 2 inch x 4 inch stakes approximately 18 inches long, called 'stoutstakes'. Live stakes have been planted through the jute matting.


Photograph: Showing zone of compacted soil broken up carefully with hand rakes, taking care to avoid damagingexisting roots. Note that where bark has formed on large exposed roots connected to living roots outside thecompacted area, they are not recovered with soil or the bark will rot.

Photograph: Showing the addition of organic matter over loosened soil. Loose undecomposed leaves collected in theadjacent woods are suitable as an amendment because the straw and jute cover will hold the surface until the leavesbreak down. Where leaves are not available, compost, sewage sludge, and peat are acceptable alternatives.


Photograph: Showing addirian of new top soil where significant amounts have been lost. Note that roots that haddeveloped bark were left exposed. Often the eroded soil can be recovered downslope and returned to its original siteHeavy clay soil should be lightened with sand or expanded slate or soil will recompact. Trampling by workers and useof wheel barrows during construction should be confined to a limited area to minimize impact.

Photograph: Showing the use of long straw as a mulch over the rehabilitated soil. Mulch is laid down in a 3 inch layerand used uncut (not shredded) from the bale. Where straw is unavailable, another layer of leaves can be added.Woodchips should not be used as they are often too "hot' and also deplete the soil of nitrogen as they decompose.


DEAD WOOD &BRUSH

In an undisturbed natural forest, dead trees and brush play an important role inproviding shelter for wildlife and food for a host of insects and decomposers.

In an urban forest fragment, numerous dead trees and large areas of brush may resultfrom a variety of impacts. Filling over the edge of the plateau can kill trees all along theslope. Similarly, a stream carrying greatly increased volumes of urban runoff canseverely undercut the edge of the channel and topple numerous floodplain trees. Ifsufficiently extensive, the resulting debris can inhibit natural regeneration and provideopportunities for the invasion of disturbance species. Because dead wood and brushcan be a liability, as well as an asset, it is important for the landscape manager toobserve carefully its impact on each site.

As a rule, individual dead trees should be left in the landscape wherever possible. Theyare used as dens by many animal species and harbor insects and micro-organismswhich provide food for many other animal species. Woodpecker populations, forexample, have increased dramatically is some places where gypsy moths have killedlarge numbers of oak trees. A useful guideline would be to leave 3 to 5 standing deadtrees per acre for wildlife. Fallen logs and branches are also important to wildlife. Twolarge and sound logs, in excess of one foot in diameter and 20 feet in length, arerecommended and as many rotting logs as possible. Where logs are abundant, somecan be moved to other locations where there is too little dead wood. The logs can alsobe placed on site to help control erosion. Partially submerged logs can be placed alongshorelines to benefit fish, birds, and amphibious organisms. Logs in a stream can bothaerate water and provide additional habitat. Leaf litter and woody debris can be reusedelsewhere to add organic matter to eroded sites.

Occasionally, however, some selective clearing may be advisable to prevent damage toadjacent vegetation or to remove dead trees which pose a direct threat to the visitor,such as along a path. Where numerous trees have fallen, the resulting branch andbrush piles can be extensive. Dead leaves and twigs may accumulate deeply enough toseverely limit the reproduction of native plants. Vines, especially disturbance speciessuch as Japanese honeysuckle, may establish quickly in the open landscape where thecanopy is now gone, heaping over branches and further inhibiting natural regeneration.Once well-entrenched, vine cover may persist for decades, displacing more diversenative habitats. Over time, such sites may also serve as a source of disturbance specieswhich can invade adjacent landscapes.

Where an open or successional landscape is desired for habitat diversity or wildlifemanagement, a grassland or shrub landscape may be preferable to a vinescape,especially where the vines are predominantly invasive exotics, such as kudzu,Japanese honeysuckle, porcelain berry, wisteria, or oriental bittersweet. Where vinesare acceptable, native grapes, blackberries, raspberries, and woodbine should befavored.


If it is desirable that a forest be reestablished, some removal of dead trees may benecessary and present no unacceptable habitat loss if other snags, logs, and brush areleft.

Sometimes brush is deliberately deposited on a slope with the expectation that it willhelp control erosion. While brush may be temporarily effective in limiting access anddiscouraging trampling, it rarely reduces erosion. In fact, it can serve to obscure theproblem while conditions worsen. It is also unattractive and makes a forest look trashed.Therefore, all brush laid on slopes should be removed, and more comprehensiverestabilization initiated.

A familiar concern with removing dead wood and brush often is disposal. Vehicularaccess may also be restricted on many sites, making transport from the site difficult.There are, however many uses for dead wood in on-site restoration efforts including thecontruction of check dams, check logs, and soil stakes described earlier as well as toimprove wildlife habitat by constructing a wildlife shelter or brushpile.

Small fragments of natural habitat can be very restrictive for small mammals. Snakeswhere they are more visible and easily attacked. Winter mortalities can also be veryhigh. The construction of a shelter can be especially valuable in reducing mortality dueto vandalism as well as winter conditions.

If well-sited, a brushpile can also provide shelter for wildlife. Select a sunny site,preferably away from human activity. Make the pile as compact as possible, laying thelarger limbs across the top to minimize wind damage. The brushpiles also improvelong-term soil quality and provide habitat for soil organisms.

Where there are no restoration needs, any unused wood can be cut and stacked alongany well-used path to be carried away be visitors. This method is often surprisinglyeffective. Where access is suitable, wood can be chipped for use off-site or as mulch forlandscaping purposes. Woodchips can often be suitably disposed of on the path itself ina layer ranging from 2-5 inches in depth. As a rule, however, woodchips should not besimply disposed of in the forest. They can form a suppressive layer of mulch whichinhibits herbaceous growth and the reproduction of many species.


Techniques: Construction of a Wildlife Shelter(Snake Hibernacula)

The accompanying plans are designed for a large, sturdy and long lasting shelterconstructed with pressure-treated wood and using a backhoe for excavation whereaccess is limited a smaller shelter, hand dug, is still appropriate. Similarly, the sheltermay also be built of dead wood on site, however, it will not last beyond a few years. Inthe most restrictive situations, a simple brushpile located in a sunny spot whichconsolidates a site's debris is suitable. A wildlife shelter should be located in a field or at awoodland edge which provide the maximum level of sun exposure and minimum ofcontact with people. It is also important that no valuable vegetation is displaced ordamaged by the construction. For the large shelter, a backhoe should dig a trench 4.5 feetwide, 8.5 feet long and 6.5 feet deep. Topsoil and root stocks of existing vegetation shouldbe stockpiled and reserved separately from the subsoil. Lay 2 full length ties on the floor ofthe trench along the sides. Place 2 of the pre-cut ties on tope of the full length ties, thusforming a rectangle. Secure the ties to one another with large nails; this will keep themtogether and prevent them from coming apart over a long period of time. Repeat theprocedure 8 times so the ties form a box. Fill the opening with stumps, logs, branches andboards almost to the top. 4 inch orangeburg (perforated) pipe (8-12 feet long) may be usedas entrance and egress points, one in each compass direction. Cover the top with 6 tiesside by side, thus forming the roof. Cover the roof with plastic sheeting or tarpaper toprevent sand from washing down from the top.Stack more logs, stumps, and branches onthe top of the ties up to 4 feet high, then cover the pile with the sand that was dug from thetrench. Cover the entire mass until the mound is about 6 feet in height. By using railroad tiesin the construction of the snake dens (hibernacula), it is predicted they will last up to 50years or more. Without the ties, the mound would only last 4 to 8 years because termites willeat the pine logs and other wood.A total of 22 railroad ties is needed for each full-sizeshelter as well as several stumps and branches and soil to cover mound. Cut each of theties in half (4-foot lengths).

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Elevation: Showing man-made wildlife shelter/ snake hibernaculum.

Success Under Stress: Managing & Restoring the Metroforest

HALF TIE. • 4FT. LONG

52

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Cross-section: Showing man-made wildlife shelter/snake hibernaculum

53

The plans and specifications for this wildlife shelter were provided by Herpetological Associates, Inc., 1018 BerkeleyAvenue, Beachwood NJ 08722,


INVASIVE EXOTICS

As soil disturbance is the most visible aspect of environmental damage in thewoodlands of the park, the spread of exotic invasive vegetation is perhaps the mostpernicious consequence. Planted woodlands and native forests alike can beoverwhelmed by exotics and end up looking like overgrown vacant lots, if adequatecontrol is not undertaken quickly enough.

The components of natural habitats found in a region have co-evolved over millenniaand produced a natural system of checks and balances. While this does not mean thatdramatic change will never occur, the overall vulnerability of a complex community tonatural stresses is reduced. The introduction and often widespread dissemination of analien species, such as Norway maple and Japanese honeysuckle, planted by man intoan environment where there are no natural controls or defenses have been devastating.

While it is true that over time natural systems will adapt the presence of a new entity ordisturbance, it is also true that this change can decimate extensive areas of nativehabitat and limit the capacity for recovery in a system already severely hampered by awide range of other environmental stresses. Indeed, some native pests are exerting amuch greater influence now than in the past due to accumulated stresses on thelandscape. The diversity and quality of protected natural areas are deterioratingeverywhere in the developed corridor along the East Coast.

When kudzu was in vogue, for example, and falsely perceived of as a cure-all forerosion, over 34 million seedlings were distributed from a single government nursery inGeorgia. Today, this plant is a menace, renowned for its unparalleled rate at which itswallows up forests and farms alike. Indeed, kudzu, once thought to be confined to thesouth, has begun a slower but still effective invasion to the north.

Though not all introduced exotic species become invasive, the success of a few speciesis more than enough to jeopardize virtually every native habitat. Honeysuckle, likekudzu, was once widely perceived as an excellent ground stabilizer. Again, like kUdzu,honeysuckle was on a massive scale with the greatest efforts coming from the railroads,which used honeysuckle to quickly cover steeply sloped embankments. Althoughgrowth is rapid and cover seems complete, the long-term results did not warrant thisoptimism. The vine's shallow, opportunistic root systems do not provide anything closeto the level of stabilization of native forest systems. Slumping and soil slippage continueto occur and surface soils are still exposed to erosion beneath the heaping cover. As itmatures, it heaps higher and higher over old stems and the number of rooting sitesdiminishes, with a probable decrease in its capacity to check erosion. Not only does thisfail to stabilize as hoped, it has proved to be highly invasive and largely free from thenatural controls in their own native habitats. Birds also help disseminate this plant,which produces abundant berries. Because of this, honeysuckle is occasionally


defended as valuable to wildlife. However. this is a very short-sighted perspective.Plenty of honeysuckle is likely to always be with us. However. the continued loss ofhabitat diversity will be devastating to birds and other wildlife. In urbanized corridors, it isdifficult to find a fragment of habitat that is uncontaminated and in places nearly allnarrow strips can be thoroughly infested. And as forests throughout the larger region areincreasingly disturbed and fragmented, they are ever more vulnerable to honeysuckle.

Equally invasive are the Norway and sycamore maples, which are gradually taking overmany forests in the northeast. Because they do not have the heaping vine form, but lookto most people like any other tree in the forest, the evidence of disturbance may be lessapparent. In late fall, however, when the leaves from other trees have fallen, thebutter-yellow foliage of the Norway maple. for example, reveal a continuous understoryof saplings. When these mature. the woodland may be entirely Norway maple,displacing a host of native species. Because almost no other species can coexist with it.the soil is often bare beneath its canopy and subject to erosion.

While vegetation, in general, is usually perceived as providing soil stability, manyinvasive exotics actually provide very poor erosion control, as compared with healthynative communities or well maintained horticultural landscapes. Norway and sycamoremaple have very large and thick dark leaves which emerge early in the spring andtypically fall off the tree long after those of the native maples, creating a shade so darkthat it severely inhibits ground layer vegetation. Even more problematic is the fact thatNorway and sycamore maples are strongly allelopathic, that is, they suppress thegrowth of other plant species due to the release of toxic substances in the soil. As aresult, once Norway or sycamore maple become established, reproduction of otherspecies comes to a halt and the ground beneath them is often totally barren. Without theadditional protection of ground layer and/or small tree and shrub vegetation, the rootsystems of the trees do not provide adequate stabilization. Even more devastating, ofcourse, is the loss of native plant communities or valuable planted vegetation.

There are few other exotic species which appear to pose such a threat to nativepopulations. The widespread dissemination of Norway maple has been accomplished.Like many other disturbance species, its vigor in our landscape is part of what made itso popular. Until very recently, more than half of the trees recommended for use on citystreets by Philadelphia's Fairmount Park Commission were varieties of Norway maple.Typically, a nursery will have more varieties of Norway maple than all other maplescombined. Philadelphia has stopped recommending this tree and some townshipsdiscourage its use, but demand for the plant is still large enough to warrant its cultivationon a massive scale.

Japanese knotweed is an even greater failure at site stabilization. Although large insize, often up to eight feet or more height, this plant is actually a stout-stemmedherbaceous plant which dies completely back to the ground each winter, leaving nowinter cover. This problem is compounded by the fact that knotweed lacks a fibrous rootsystem, which would provide greater soil stability. Spreading quickly by rhizomes, it


soon displaces other more stabilizing vegetation completely. Given its behavior pattern,it may also be highly allelopathic.There are, at present, no effective natural controls for these plants. Even though Norwaymaple, for example, is subject to numerous diseases and pests which create problemsin horticultural settings, as yet none has checked its spread in the wild. Over time, it isinevitable that some organism will take advantage of so widespread a host but, in themeantime, extensive areas of native habitat are being decimated and their recovery isseverely hampered by a wide range of other environmental stresses.

It is also clear that a very large effort is required to repair the damage done. There areonly a few other exotic species which appear to pose such a threat to nativepopulations. Purple loosestrife, escaped from garden cultivation, has overwhelmedwetlands from New York to Minnesota. Its spread is so rapid that a single plantobserved is considered an infestation. Even today, new exotic plants are still beingpushed as cure-ails exactly because they spread so rapidly.

The future of our native forests may depend on our taking immediate action. The state ofIllinois, for example, is considering legislation introduced in 1987, for an Exotic WeedControl Act, to prohibit the sale and planting of problem exotic plants in Illinois.

It is strongly recommended that no species which has demonstrated itself to be asuccessful invader at the expense of native habitats in the region, or is even suspectedof being a pest, be planted at all, because of the threat they pose to the woodlands,planted sites, and regional natural areas. This is a very conservative policy, but theconsequences of being too optimistic may be very costly to remanant habitats. Urbanwildlands are already severely stressed and it is important not to compound that risk.This is especially relevant to woodland areas, where it is desired that nature take itscourse as much as possible.

What makes a plant an exotic invader, instead of a simple garden escapee? It is all aquestion of degree and context; how fast, how widespread, and most importantly to whatextent does it displace native habitats. Appropriate evaluation of exotics requires carefulobservation of their behavior throughout the region. It is critical to identify what we call'Huns', those plants which are not only reproducing rapidly in highly disturbed sites,such as vacant lots, but are also making significant inroads in less disturbed areas, suchas large woodlots. The most conspicuous trait of a 'Hun' is that it displaces wholecommunities, not just a few species. No one looking at plants in the eastern corridor, forexample, can fail to have observed knotweed and Norway maple. There is already morethan enough evidence to alert any park manager to the seriousness of the threat thesepose to native habitats.

A ban may seem extreme, however, many of the species are dispersed by birds andquickly traffic over fairly large distances. All are extremely difficult to eradicate onceestablished and none is so critical to landscape character that it cannot be replaced byanother less threatening species. Beyond jeopardizing native habitats, invasive species


typically represent a significant maintenance drain on more horticultural landscapes andoften outcompete desirable exotics as well as indigenous species.

An informative article on the real costs of invasives is entitled, Exotics &their EcologicalRamifications, (1987). Harty, F.M., Natural Areas Journal, vol. 6 no. 4:20-26.

It is strongly recommended that the following species be banned from being planted inthe Northeast:

Trees:

Norway mapleSycamore mapleRussian oliveAutumn oliveOsage orangeWhite mulberryWhite cottonwood

Shrubs & Small Trees:

BarberryWinged euonymousAmur honeysuckleTartarian honeysuckleBlunt-leaved privetSmooth buckthornShining buckthornMultiflora roseRugose rose

Vines:

Porcelain berryOriental bittersweetJapanese honeysuckleSilver fleece vineKudzuJapanese wisteria

Herbaceous Plants:

Yellow flag irisPurple loosestrifeJapanese knotweed

(Acer platanoides)(Acer pseudoplatanus)(Eleagnus angustjfolia)(Eleagnus umbellatus)(Madura pomifera)(Morus alba)(Populus alba)

(Berberis japonica)(Euooymous a1atus)(Lonicera maackii)(Lonicera tatarjca)(Ligustrum obtusjfolium)(Rhamnus cathartica)(Rhamnus frangula,)(Rosa multiflora)(Rosa rugosa)

(Ampelopsis brevipedunculata)(Celastrus orbjculata)(Lonicera japonica,)(Polygonum aubertii)(Pueraria lobata)(Wisteria floribunda,)

(Iris pseudacorus)(Lythrum salicaria)(Polygonum cuspidatum)


The control of exotic invasive species is considered in this manual to be one of the mostcritical management tasks necessary to the conservation of native plant communities.This is as simple as it might sound. At present, it is not remotely feasible, or necessarilyeven desirable, to remove all exotics. Some species which are largely confined to areasof severe disturbance such as the tree-of-heaven (Ailanthus altissima), bring welcomegreen into areas which may be incapable of supporting vigorous native communities.Instead of eliminating it, we should be grateful for its tolerance of inhospitableconditions.

The approach taken in this manual is to concentrate on the most pernicious species bywaging a continuous effort of monitoring and control. The broad goals are to keepundisturbed areas free of invasion and, in areas of moderate disturbance, toincrementally remove exotics and replace them with native species. In the most severelydisturbed areas, the objective may simply be to contain the exotics. This approach is notunlike medical triage which identifies those who are beyond assistence, those who donot need assistence, and those who can be helped.

Even when the need to control invasive vegetation, such as honeysuckle is accepted,how to achieve effective results is often unclear or hotly debated. The most frequentconflicts arise over the use of herbicides. For most people, the justification for using anherbicide is the perception that this will require less labor. Managers note that it isimportant not to devote a disproportionate amount of energy to control a few areas if theinvasives are busily spreading unchecked elsewhere, because there is no labor leftavailable. For others, the most intractable aliens, such as Norway and sycamore mapleand Japanese knotweed, seem to be simply uncontrollable without herbicides. Somehave suggested Japanese knotweed is simply uncontrollable I There is always thedanger, however, of overrelying on herbicides.

In a system where pesticide use is more restricted and judicious, limited herbicidemanagement to control exotics might account for only a fraction of the current haphazardand routinely excessive pesticide treatment to support poorly adapted ornamentals. Ifwe give up herbiciding gravel and mulch beds, roadsides, and building marginsperhaps some pesticide control of exotics would be viewed as more acceptable.

Because arguments in favor of both sides are strong, we have provided bothrecommendations for control which are entirely mechanical as well as procedures whichinclude the use of herbicides, but in combination with other non-chemical procedures tominimize the reliance on herbicides. Our guidelines for herbicide use also seek tominimize the volume of chemical used and to maximize the selectivity of the application.When herbicides are used, it is recommended that you contact an integrated PestManagement (IPM) practioner. This policy seeks to achieve effective control rather thantotal eradication and to minimize the use of chemicals by employing a combination ofmethods, inclUding mechanical and environmental controls, such as prescribed burning.


In response to these concerns, we recommend the following guidelines:

1. Every effort should be made to minimize the use of herbicides. In someareas, any herbicide use at all may be deemed inappropriate, particularly wherewildlife might be jeopardized.

2. Wherever herbicide use is being considered, entirely mechanicalnon-herbicide procedures should be implemented as well and evaluatedfor effectiveness.

3. Herbicide use should be confined, to the maximum extent possible, toseverely invasive exotic species.

4. All management which includes herbicide use should follow theIntegrated Pest Management (IPM) approach, which advocates combiningherbicides with non-chemical procedures to minimize the reliance onherbicides.

5. The initial management should include at least one mechanicalclearance before any herbicide is used.

6. Herbicide use should diminish over time on each site, as initial controlis accomplished and more desirable plant communities are established.Where use has remained high for several years, the managementprogram should be reevaluated.

7. Be consistent and continuous with management. Follow-through iscritical. Do not initiate management on an area larger than can besustained over time. Where prioritization is required, protecting theleast disturbed habitats should be given the highest priority.

Zen and the Art of Motorcycle Maintenance (Pirsig, 1974, p. 158) states, "Assembly of aJapanese bicycle requires great peace of mind." We can easily adapt it to say thatpeace of mind is required in the control of exotic invasives. Persistence and patience,not weaponry, is the key to control. What is important is not how hard you hit the target,but how often. After all, we are talking about plants that have shown themselves to befavored and spread by disturbance. They are all resilient, prolific, and ubiquitous.

There has also been serious concern raised about the spread of several native species,foremost among them the black cherry (Prunus serotina). The 1982 tree inventory inCentral Park, for example, revealed that over 19% of the trees in the park greater thansix inches in diameter were black cherry, and the ratio was far higher if one includessapling size trees. This plant is clearly reproducing aggressively. Some have arguedthat, in the interest of maintaining diversity, this species should be treated like aninvasive exotic. There are, however, some important distinctions. A defining


characteristic of an invasive exotic is that native species and often whole nativecommunities are literally displaced. The cherries are not invading healthy and diverselandscapes, such as oak and beech forests. At worst, they are reproducing well on siteswhich were previously turf or tended shrub beds and establishing dense stands whichtemporarily occupy the space. In many cases, it is not native species they are crowdingout, but exotic disturbance vegetation. Perhaps more importantly, the cherries do notpreempt the return to native forest. If the exotics could be kept at bay and adequate seedsources for indigenous plants were available, natural succession would graduallyreplace the cherries with more diverse native vegetation.

In sharp contrast, where Norway maples are established, there is no evidence thatnative communities would gradually colonize the site, even if the cherries were kept atbay. More than anything else, the cherries are taking advantage of reduced levels ofmaintenance which permit early successional vegetation to colonize many areas of thepark which were formerly tended. Because disturbance levels are high and there is onlylimited representation of native habitats in the vicinity, only a few natives, all easypropagators, account for a disproportionate amount of new growth. They represent agreater problem in horticultural landscapes, where they grow like weeds, than they do inthe woodlands where their reign will be short-lived if more stable forest cover isestablished. American elm and black locust are similarly prolific and will also becontrolled naturally once more forest-like conditions prevail. This, of course, is thecritical distinction. Cherries, elms, and black locusts are easily controlled naturally, thatis, by other native vegetation. This is not at all true for knotweed and Norway orsycamore maple, which actually control and eliminate native vegetation.

For this reason, the cherries and other prolific natives are not appropriately viewed as athreat to native habitats, but may be deemed as a maintenance problem in thehorticultural landscapes. Where they are abundant in woodland areas, it may bedesirable to remove cherries and replace them with more diverse native vegetation ofgreater value to wildlife and scenic character. However, this may not be a recommendedcourse of action, where exotic invasives currently pose a much greater threat. Whenever

. trees are cut, it is an open invitation to disturbance species to colonize. First priorityshould be given to stabilization and exotics control. Once this is accomplished, thenselective removals accompanied by additional planting can be considered.

Occasionally it is suggested that native species are more vulnerable to urban stresses.Unfortunately, however, the exotics which are held up as successful examples often areinvasive, causing problems in planted beds and woodlands alike. While the full breadthof native communities is not sustainable in the city, more than enough species survive tocreate rich and compelling landscapes if appropriately managed. While exotic foodsources are also used by wildlife, they do not appear to be necessary to wildlife.

Another aspect of woodland management is that native plant communities, onceestablished, will be far more self-sustaining than the more maintenance intensivelandscapes that characterized Olmsted's era. Exotics, however, often become pests if


they naturalize well and, if they don't reproduce, they fail to support a naturallyself-sustaining system and must be tended and replanted. This is not to say that nativecommunities will be maintenance-free, but that the care required is more appropriatelydescribed as management, rather than maintenance, and that the major activitesrequired will involve more repair of damage from use and exotics control than directhorticultural support of the plantings. This is especially important given the realities ofthe maintenance dollar today and the pressing need for many other maintenance tasks.

Despite the evidence that exotics pose such severe threats and cost so much to control,new species are continuously being promoted on a grand scale. A current example isthe Sawtooth oak (Quercus acutjssjma), pushed as potentially valuable for wildlife. It isfoolhardy to spread it throughout the landscape and then sit back to see if it naturalizesall too well. Because so little is known about many exotics, it is strongly urged thatplantings in woodlands be confined to native species. Where greater diversity isdesired, it is worth concentrating effort on reintroducing native species, including thenew American chestnut crosses which are being developed currently.


62

Photograph: Showing a Norway Maple invasion in this relic urban woodland. Hundreds of Norway maple saplings,still holding their leaves in late fall, dominate the understory. Reproduction by native canopy and understory treeshas almost halted, while the Norway maple gradually displaces an entire forest community.

Photograph: Showing Japanese knotweed, Japanese honeysuckle, and silver fleece vine completely displacingthe native floodplain forest along this urban stream channel.


63

LANDSCAPE MANAGEMENT STRATEGIES:

Control of Exotic Invasive Vegetation

The two most serious exotic invasive pests in the region are Norway maple andhoneysuckle. Both occur most extensively along typical disturbance corridors such asroads, paths, railroads, and the devloped edges, though their distribution is occasionallywidespread. The approach taken in this Manual is to wage a continuous effort to controlthese species. The broad goals are to keep undisturbed areas from becoming infestedby monitoring and removing invaders before they become entrenched. Where there ismore disturbance and infestation, the goals are to reduce the stresses on the site, andincrementally remove exotics and replace them with native canopy species. In themostly severely disturbed areas, the objective is simply to contain the exotics. Thisapproach is not unlike medical triage, which identifies those who are beyondassistance, those who do not need assistance, and those who can be helped.

The methods described for these two species may be adapted for use on other pestspecies. Continuous experimentation and evaluation is mandatory.


Control of Exotic Invasive Vegetation:

Japanese Honeysuckle (Lonicera japonica)

Native to Japan, China, and Korea, Japanese honeysuckle is basically anearly successional invader, lying dormant in mown pastures and taking a firm hold inwoody oldfields. However, it is also found in the light shade of disturbed woodlands. Asforests throughout the region are increasingly fragmented, they are more vunerable tohoneysuckle, which invades from adjacent cleared areas. Although intolerant of heavyshade, honeysuckle will persist even in the interior of a mature forest as a sparsegroundcover.

A trailing and mat-forming vine, Japanese honeysuckle, once entrenched, formsmonospecific patches. The rate of spread of the plant varies with the degree of localinfestation, the age of the patch, and the amount of disturbance on the site. Widelydisseminated by birds and small mammals who eat the berries, once established,honeysuckle can hold a site very successfully by its ability to spread vegetatively -- itslong trailtng stems are able to root at every node. Honeysuckle, like kudzu, was oncewidely perceived as an excellent ground stabilizer. However, when young, although theplant roots frequently, these root systems are small and shallow, and as the plantmatures, heaping up over the older stems, the number of rooting sites is greatly reducedand the ground beneath the mound is virtually bare.

Takeover by Japanese honeysuckle creates a static landscape by suppressingreproduction. Because of its ability to climb by twining, the thick and impenetrable mass,produced by the many intertwined stems, inhibit tree and shrub germination and youngsaplings are strangled and eventually completely covered. If a dense canopy candevelop, honeysuckle diminishes and is reduced to a flatter, ground-hugging vine;however, reproduction of other species is still curtailed.

Japanese honeysuckle is semi-evergreen in the mid-Atlantic states, keeping its leavesuntil late November. As with many other Asian species, late fall is an excellent time tomonitor and evaluate the extent of honeysuckle takeover, as these plants remain greenafter our native plants have lost their leaves, and are then clearly visible in thelandscape. In addition, the characteristic heaping form of honeysuckle is so familiar andunbiquitous, it can be easily spotted at any time of year.

Treatment for Eradication

Where Japanese honeysuckle has completely overwhelmed a site and no nativespecies are present, a black plastic mulch can be used to kill the plants. Although thisplastic is unsightly, it is later removed and involves no herbicides. First, cut and removethe heaping portions of the vines. A blade weed-whipper can be especially useful forcutting the stems. The black polyethylene should be held tightly in place, using staples


or stakes. Where appearance is an issue, an open mesh fiber can be used to secure aleaf mulch over the slippery plastic. It may take at least 18 months to adequately controlthe honeysuckle. When the plastic is removed, complete restabilization of the site isnecesssary. An erosion control blanket and/or check logs and additional replanting areusually required.

Where Japanese honeysuckle is mixed with desirable native species, repeatedweeding of the honeysuckle will gradually give a competitive edge to the other plants.However, real diligence is required. These plants must be pulled up gently by the rootswhen the soil is moist and all runners that have rooted pulled up as well. Although thisapproach is tedious at the outset, it will provide excellent control over time. Some limiteduse of herbicides, in combination with removal, can be very effective while reducing theamount of herbicides required.

Similarly, honeysuckle growing in trees can be tackled by severing the stemconnections to the ground. Again, a blade weed-whipper is useful or a rachet lopper.The vines can be left to rot in the trees if appearance is not a problem. An herbicidetreatment of the stumps is important, otherwise mechanical removal of a sometimesmassive rootstock is the only option.

When herbicides are used, the object is to minimize the use of the herbicide bycombining it with mechanical procedures. Several successive cuttings can be extremelyeffective in exhausting the rootstocks and at least one cutting and removal of the topgrowth is required before applying the herbicide. Herbicide should be applied only tothe places of resurge, where the vine is resprouting, during the active growing season.

Subsequent herbicide applications should function largely as a monitoring operation,catching any recovery sites before new root systems develop.

Recommended Treatment Schedule

May -- complete hand cutting and removal of vinesJune -- complete hand cutting and removal of vinesAugust -- Initial herbicide applicationOctober or November -- Follow-up monitoring and herbicide application

The honeysuckle vines should be cut to 12-18 inches above ground in May, and againin June, some 4 to 6 weeks before the initial herbicide application. This will allowsufficient time for the remaining vine to resprout new foliage, which will then be treatedwith the herbicide application. Because the pieces of the stem re-root very easily, vinesshould not be chipped on site. All cut portions of vine should be removed from the site toeliminate re-contamination. If placed in mulch or compost piles, adequate time mustpass before use to ensure enough rotting to prevent introduction of the plant elsewhere,via the mulch.


Safety Measures

The herbicide applicator must be state-licensed and must possess the necessaryinsurance required by law. All precautions and environmental hazard protections onproduct labels must be observed. Only labelled herbicides in original containersobtained from the basic manufacturers must be used. Only clean tap water should beused for mixing and rates indicated on the product label must not be exceeded.

The spray must be carefully directed to resprout areas only. Avoid spraying desiredplants and minimize spray contact with the soil. To effect selective application, avegetable dye should be added to the mixture to provide an exact record of the areatreated.

The weather during application must be warm, between 75° - 95°F is preferred, toensure rapid uptake by the plant. The air must be calm with less than 5 mph winds toavoid spray drift. Do not spray herbicide into or near water.

Recommended Herbicides and Application Rates

Herbicide application shall use: "Roundup", applied with a 3-gallon backpack sprayerwith 80-02 or 80-03 nozzle. Fill tank 2/3 full with clean water; add 6 fluid ounces or 0.375pints of "Roundup", and then finish filling tank with water. Mix thoroughly. Apply as a finespray at a pressure of 40 to 50 #psi to leaves and stems for complete coverage.

After the first year's herbicide treatment, continue monitoring and retreat plants onceannually, clearing in June if necessary and herbiciding inAugust.

Products

Glyphosate. "Roundup", (EPA Reg. No. 524-308-AA), as manufactured by MonsantoCompany Agricultural Products, 51. Louis MO 63167.Water based dye, Bulls Eye, as manufactured by Milliken Chemicals, Division of Milliken&Co.


Photograph: Showing vine control at a disturbed forest edge. Japanese honeysuckle, porcelainberry,and wisteria hang in curtains at the edge of this urban slope forest, where it abuts the developedplateau. Control begins with mechanical removal -. here, a weedwhipper with a saw blade, instead of anylon line, is used to cut the top growth.

Photograph: Showing top growth being hauled away. In this case the sheer volume of cut vinesrequired a front end loader for removal. Vines must be carefully disposed of as many will root readilyfrom pieces of stem or root.

Photograph: Showing spot application of herbicide after cutting and removal of top growth. Herbicideapplication is restricted to remaining portions of the plant where regrowth is occurring.


Control of Exotic Invasive Vegetation:

Norway Maple (Acer platanoides)

Native to continental Europe, this invader is one of the biggest threats to thenortheastern deciduous forest. Escaped from cultivation in suburban and rural areas,Norway maple can be found throughout the region, displacing complex native forestplant communities with monospecific woodlands.

Prodigious quantities of mobile, windborne seeds, reproduction in sprouting, a tolerancefor dense shade, and an ability to thrive in a broad range of soil conditions give theNorway maple a competitive edge over many native species, especially in areas ofdisturbance. Once established, Norway maple holds the ground for decades, releasingpowerful chemicals which inhibit the germination of other species. In forested areas, thisspecies is typically found at the edges and within the interior, following roads, pathways,and erosion channels. However, the vigorous spread of Norway maple is not limitedonly to disturbed forests. It is so widespread that acres of abandoned fields throughoutthe mid-Atlantic states have been transformed into monospecific woodlands of Norwaymaple within a period of 30 to 40 years, precluding the succession of native habitats.

A dense but weak wooded tree, Norway maple is prone to damage by winds and iceand snow loads and rots quickly when wounds are untreated. Like other maples, it issubject to verticillium wilt. Despite its many problems and its invasive behavior, Norwaymaple is still widely planted and appears on many recommended street-tree lists.

The fall is the best time to monitor and evaluate the extent of Norway maple takeover, asthese maples remain dark green when the red and sugar maples are in full color. Onlyafter the native trees have lost their leaves will the Norway maple turn a deep yellow,easily visible in the leafless forest.

Treatment for Eradication

Norway maple sprouts vigorously, especially when cut, and can be very difficult tocontrol mechanically, although repeated sprout cutting will eventually kill the tree.Where numerous seedlings are present, hand pulling is effective in removing them, butthe entire root system must be pulled up with the shoot, and ultimately the major seedsources must be eliminated. Convincing an owner to cut down a large specimen treewhich is deseminating seeds over a wide area can be an intractable problem. However,recently, a number of horticultural and botanical institutions have taken the lead inefforts to remove seminal trees from their parks and campuses and to restrict theplanting of Norway maple in the wider community. Since Norway maple is soaggressive, an approach combining both mechanical and chemical methods appears tobe most effective.


Because of the widely varying sizes of trees involved, two different treatment modes arerecommended. In the first, the tree is cut and removed and the herbicide treatment isconfined to the cut surface of the stump. This method is called 'notch and frill'. In othersituations where it is not possible or desirable to remove the tree, a strip of herbicide inan oil medium is applied to the circumference of the trunk. This treatment is mosteffective on younger, smooth-barked trees and is especially suitable for treating siteswhere numerous small saplings have become established. This procedure is lesseffective on trees over 6 inches in caliper or where a platy bark has developed. It cantake several months for death of the tree to occur. Follow-up applications are sometimesnecessary. It is critical to monitor treated trees and apply a foliar spray to resprouts.Using either stump or trunk treatments initially, instead of a foliar spray, minimizes theamount of herbicide used while permitting very accurate application.

Recommended Treatment Schedule

Mid-August through September -- Initial herbicide application on trunk or on stumpimmediately after cuttingJune through August -- Follow-up monitoring and foliar herbicide application

The herbicide application should be timed to effect maximum translocation to the rootzone.

Safety Measures

The herbicide applicator must be state-licensed and must possess necessary insuranceas required by law. All precautions and environmental hazard protections on productlabels must be observed. Only labelled herbicides, in original containers, obtained fromthe basic manufacturers should be used. Do not exceed use rates indicated on theproduct label and be sure not to exceed the amount of active ingredient per acrespecified on the label. This herbicide is an effective killer of woody species; however, itis also extremely dangerous to humans and must be used with extreme caution. Oilimpervious gloves should be worn. The basal oil is combustible and should not be usednear fire.

To effect selective application, a vegetable dye should be added to the mixture toprovide an exact record of the area treated. Warm weather during the application isnecessary to ensure rapid uptake by the plant. A temperature between 75° - 95°F ispreferred. For spray applications, the air must be calm with winds of less than 5 mph toavoid spray drift. Do not apply herbicide to water. Effective control will be reduced in wetweather. Lastly, when trees are to be cut, caution should be taken not to disturb adjacentvegetation. For larger trees, topping may be necessary, lowering the upper branches tothe ground with ropes.


Recommended Herbicides and Application Procedure

A low volume basal (LVB) control treatment is recommended, using basal oil and aTriclopyr ester herbicide, such as Dow Chemical's "Garlon 4 Herbicide". The oil mediumpenetrates the bark and woody tissue, transporting the herbicide along with it, permittinga very selective application and the use of less herbicide than a foliar spray, whilereducing drift and worker exposure. A dye is also added to clearly delineate the areatreated.

A 25% concentration (1:3 ratio) has been found to be effective. One gallon of herbicideshould be mixed with three gallons of basal oil and stirred for approximately ten minutesuntil a clear solution is obtained. Add up to 0.4 ounces of basal dye per gallon of basalspray mix. Shake or stir until the liquid is uniformly mixed. Use a backpack sprayer witha spray wand fitted with a spray system 5500 nozzle and a Y-2 tip to achieve a precise,drip-free, low-volume application. Only a small amount of the herbicidel oil mix shouldbe applied. Lightly spray the lower circumference of the stem, root, collar, and anyexposed roots. Do not allow the mixture to puddle or drip around the base. The height ofthe treated band should be 2 to 4 times the caliper of the tree.

On a cut stump, the cambium layer should be sprayed as soon as possible after cuttingas well as the remaining bark and exposed roots to discourage resprouting. Again,puddling and dripping at the base should be avoided. It is unnecessary to spray theheartwood area.

Contact with the cambium layer can be increased with the "notch and frill" method. Usean axe to peel back the bark to allow greater exposure of the cambium tissue.

Products

Triclopyr, "Garlon 4 Herbicide" (EPA, Reg. No. 464-546), as manufactured byThe Dow Chemical Company, Midland M148640.

Basal Dye, "Automate Blue 8", as manufactured by Morton Thiokollnc., MortonChemical Division, 333 West Wacker Drive, Chicago, ILL 60606 - 1292.

Basal oil "Arborchem Basal Oil" (Hazardous waste No. 0001 Ignitable), as supplied byArborchem, P.O. Box 1567, Fort Washington PA 19103.


FOREST VEGETATION RESTORATION

Replanting is the aspect of restoration that is usually most eagerly anticipated. And justas most people want to start replanting prematurely, before disturbance is controlled,there is also a frequent tendency to want to start at the end rather than the beginning,with the rare and the unusual rather than with the common and the typical. The mortalityrate for forest plantings can often be very high making it especially important to assesswhat is really feasible in any given situation. Perhaps the most difficult task for anymanager is learning to 'read' the landscape, to take the cues provided by what is therenow about what is likely to work. Ideally the manager also will have been observing thelandscape over time while stabilizing erosion and removing exotics. In order to helpdetermine what plants are most appropriate and where, practice the habit ofobservation.

The most important place to begin is with the existing habitats on the site.

Describe the environmental conditions as fully as possible and the range of native forestplant communities which might be found locally in such environments and how theychange over time. If the forest has been substantially modified look for the closestnatural analog. Compare the native plant communities in undisturbed areas with thosethat typify more disturbed conditions. What's the habitat? What are the environmentalconditions? What sequence of habitats and plant communities might occur on this siteover time? What is succession under undisturbed conditions? How does it change whendisturbed?

Look at each landscape, preferably over time, to evaluate what is happening on its own.Are, for example, canopy species reproducing on their own? If so, where and why? Arethere Norway maples competing with the natives? Does the shrub layer needenhancing? Where are shrubs occurring naturally? In what places would new plantsexperience the least competition from established vegetation. Try to see the landscapechanging before your eyes. What did the landscape look like ten years ago? What will itlook like next year? Ten years from now? Fifty years from now? How might this bealtered with management? Ask yourself as many questions possible about the region ingeneral and the relationship of this landscape to it. Ideally, this exercise should be adialogue engaging a vareity of different people who are familiar with the site. Go back tothe site as frequently as possible and always compare and contrast different sites. Testyour observations out with others. There are two journals that are very helpful.

Natural Areas Journal of the Natural Areas Association -- "The Association is a nationalnon-profit organization involved in the identification, preservation, protection andmanagement of natural areas and elements of our natural diversity."Published by theNatural Areas Association, 320 South Third Street, Rockford, IL 61104.

Restoration & Management Notes --"A forum for the exchange of news, views, andinformation among ecologists, land reclamationists, managers of parks, preserves and


rights-of-way, naturalists, engineers, landscape architects and other committed to therestoration and wise stewardship of plant and animal communities." Published by theUniversity of Wisconsin Press, University of Wisconsin - Madison Arboretum, 1207Seminole Highway, Madison WI 53711 (608) 263-7889.

The single most informative book on learning to observe plant behavior must be Ib..e.Natural Geography of Plants by Henry A. Gleason and Arthur Cronquist, published byColumbia University Press in 1964. This book has been out of print for years and mayrequire a book search of used bookstores.

Seek out descriptions of regional vegetation such as Vegetation of New Jersey byMurray Buell and Beryl Robichand, Rutgers University Press, 1973 or The NaturalGardens of North Carolina by B.W. Wells, University of North Carolina Press, ChapelHill, 1967.

A brief recommended reading list is included at the end of this manual.


CRITERIA FOR FOREST REVIEW & EVALUATION

Configuration

One of the most critical aspects of a forest is its configuration. The continuous forestcover which greeted the European settlers has been reduced to fragments and strips inan increasingly developed context. Species composition has been affected, invasivealien species and pests have been widely disseminated, and natural processes, suchas fire or rainfall and recharge have been substantially altered. Most endangered is theforest interior and the species limited to that environment. While a popular axiom holdsthat because forest edge conditions are favored by wildlife (often 'game species'), thecreation of more edge is desirable, a more realistic view is that forest edge abounds,while the amount of forest interior is diminishing steadily.

Measurements of the distance into the forest over which edge effects occur are variable,and may range over 300 feet. Therefore, a block of forest 1,000 feet square or almost 23acres in size can support little more than 3-1/2 acres of interior habitat. A minimum of tenacres of forest is required, roughly circular in shape, to reliably support any interiorhabitat at all. Clearly then, every effort should be made to minimize disturbance to anyforested blocks over ten acres in size. This includes road building and facilitiesdevelopment as well as the clearance of vegetation. Where disturbance does occur, itshould be confined to the edges, which are already subject to more disturbance andmore accessible to management. Since most disturbance in a forest occurs on theedges, large unbroken forest tracks require the least management of all configurations.

The long-term management of smaller and narrower forested areas, which might notnecessarily support interior habitat, is also facilitated by limiting the amount of edgecondition created and sustaining a less fragmented pattern. Long-term managementcosts will be reduced and long-term maintenance of native communities will be fostered.

Continuity

Continuity is as important to natural systems as configuration. Islands of habitat isolatedfrom surrounding natural areas experience a decline in native species diversity and areless adaptable to stress over time. Management and proposed alterations in currentforest patterns should always encourage, rather than reduce, the continuity of naturalhabitats. Critical forest linkages should be protected and missing links should bereestablished through management. This is equally important at all scales of thelandscape.

Natural Processes

A major goal of management is to undertake the least intervention necessary to achievethe desired condition. In all cases, where natural processes regulate and sustain the


habitat, the need for outside management diminishes while the health of the wholelandscape system is superior.

Environmental conditions have been substantially altered by man's activities over timeand severely compromise the long-term prospects for the sustenance of complex naturalsystems. Some impacts are virtually global, such as the greenhouse effect, must beaddressed at every scale at all times. The maintenance of expansive forest cover issomewhat helpful, for example. Others, such as acid rain are expressed more regionallyand can be substantially impacted by activities and regulations at the federal and statelevels. Still others are operative almost entirely at the local level and the gradualaccumulation of negative impacts can be substantially turned around by actions takenon a single site. It is these issues that are primarily addressed in the ManagementManual.

Fire

The control of fire has been a focus of forest management for so long that many peopleforget that fire was once integral to the natural processes of the forest. Some areas, suchas sandy, barren sites with mixed oak and pine often burned more frequently andvisibily, but no forest does not have a fire history. Recent management efforts haveconcentrated on a rediscovery of the importance of fire to the management of naturalareas, as well as to the beneficial effects and relatively low cost of fire as a managementtool. Management approaches range from virtually wild fire cycles which are beingreinstituted on large tracts where a major conflagration would not pose undue hazard tosettled areas to annual winter burns over smaller areas to favor certain game speciesand reduce the likelihood and severity of wildfire. Ultimately, the goal of all firemanagement should be to restore as near a natural fire cycle as possible. In mostdeveloped areas, light controlled burns limited to restricted sites are probably the mostfeasible.

The National Park Service recognizes the importance of fire as a management tool.Consequently, guidelines for the control of wildfires and the management of prescribedand research burns have been developed and are described in Wildland fireManagement: NPS 18. Major topics included in this Manual are the identification ofroles and responsibilities of governmental agencies, procedures for fire analysis,documentation, and staff training and distribution, as well as guidelines for wildfirecontrol and management objectives for prescribed burning. Local air managementregulations vary and should be reviewed. Wherever possible, local fire departmentshould be involved in order to gradually develop a wider network of personnel trained incontrolled burning of landscapes.

Highest priority should be given to reestablishing fire in larger forested tracts, especiallythose which support interior. A pUlsed cycle, with varying intervals of burn, rather thanregular intervals, is preferable. For example, annual burning for the first few years in aforest to reduce fuel accumulation and renew herbaceous cover may also stimulategermination of oaks and other woody species. At this point, fire could be withheld to


allow the new saplings to develop to a sufficient size so that they would not be killed bya light ground fire.

Second priority for fire management should be given to those areas where it can meetspecific management goals now achieved with more destructive methods, whilemaintaining stable cover and reducing long-term management costs. For example,woodland areas currently managed by mowing, which often fosters exotic invasion andencourages erosion, could be managed by fire to form more stable herbaceous and lowshrub growth while still increasing visibility.

There are several caveats to fire management. Adequate control of a prescribed burn isdependent on a system of fire breaks, which may include natural features, such asstreams and wetlands, or built features, such as roadways and lawn areas. Where newfire breaks are required, careful review is mandatory to ensure that the firebreak doesnot serve as a route for disturbance, disrupt natural drainage, or otherwise adverselyimpact the forest. Secondly, particular attention should be paid to the possible hazardsof smoke reducing visibility on roadways.

The components of natural habitats found in a region have coevolved over millenniaand produced a natural system of checks and balances. While this does not insure thatdramatic change will never occur, the overall vulnerability of a complex community tonatural stresses is reduced. The introduction and often widespread dissemination of analien species such as Norway maple and Japanese honeysuckle by man into anenvironment where there are no natural controls or defenses have been devastating.

Evidence is mounting that restoration practices which foster more natural fire andhydrologic cycles make the natural habitats more resistent to invasion by exotic plantsand animals as well as to debilitating diseases and pests, both introduced and naturallyoccurring. Therefore, management which sustains natural processes and patterns inorder to foster a healthy diverse community is the most resistent to a wide range ofenvironmental stresses. The restoration of native shrub and understory layers and thereestablishment of a natural fire regimen appears to be more effective in controlling pinebark beetle, for example, than vigorous eradication and clearance efforts. Unfortunately,past management often has fostered the spread of exotic disturbance species and hastipped the scales heavily against native communities, warranting a concerted effort tomitigate the consequences.

Management is purposeful and has a goal. The goal may be as simple ascontrolling exotics so that the native communities can develop. But whenplanting is also a goal, it is important to develop a site restoration model,that is a native habitat which serves a landscape model for each site. Itshould represent a good fit to the existing conditions with the highest reasonable level ofrestoration. Examine the continuum of landscapes which might occur and select amoment in time. In a forest landscape in a developed area it is usually desirable toadvance in time as most area landscapes are already successional and recentlydisturbed. It is the older forest there is often the least of. Again, please note that thisrecommendation conflicts with the frequently heard suggestion to thin the canopy in


order to develop continuous shrub or grass cover. The forest is stabilized by amulti-layered system of roots of the multi-layered vegetation above. The ground layermay be patchy, but if relatively undisturbed will sustain protective layer of leaves andorganic litter over the soil. Therefore, the object is not necessarily to obtain one verydense layer but to establish a more complex system.

It is notable how often a forest dies from the ground up. First the smaller plants, bothwoody and herbaceous are trampled. The canopy may be the last to go, declining foryears above a trampled, compacted and eroded ground. On the other hand, restorationof a forest usually proceeds from the canopy down, dealing with the smallest plants last.Where the soil has been disturbed, the use of straw and jute affords surface protectionand lasts the several years it may take for vegetation cover to develop. In themeanwhile, where planting is desirable there are several guidelines suggested forreestablishing the forest layers.

Guidelines for Reestablishing a Forest's Layers:

1. In forest landscape, the first priority is trees, in particular establishinga closed canopy. This effects some control over those exotic invasives which areintolerant of shade, or at least less aggresive in shade, while establishing the definingcharacteristic of a wooded landscape, a closed canopy. In older landscapes, under reliccanopy trees or where turf and planting beds have been released under old specimentrees, the most suitable trees are likely to be the same canopy replacement speciesfound in local natural areas, such as the beech, and oaks, and hickories of mesicslopes. The species of temporary forest gaps such as tulip poplar, black birch, and blacklocust are ideal in small breaks in forest cover.

Where larger discontinuities in woodland cover occur, red maple and ash may be ideal.The actual site, however, should inform the manager about what species are the mostsuitable. Remember too, that while the canopy layer is being planted first, a wholecommunity is being established, such as an oak/hickory association with a dogwoodunderstory, and a spicebush shrub layer and woodbine, ferns and woodland aster onthe ground. Plant the trees in patterns which have been observed on the site or inanalagous habitats, not like an orchard or plantation.

2. Once the canopy is closed, the second priorities are the understoryand shrub layers. The understory layer will include smaller, younger canopy trees aswell as typical understory species such as dogwood and sassafras. Similarly, seedlingsize tree species are characteristic of the shrub layer growing beside the viburnum ormountain laurel. The plants should be situated where yOU'd expect to find themnaturally. Typically, shrub growth will be more dense at edges in gaps, in dampdepressions, and anywhere that disturbance has been limited for a very long time.

3. The re-Introduction of herbaceous and groundlayer plants is probablythe trickiest. Expect some mortality. Start with small scale experiments.Monitor over a long time period. Put each species in the environment you'd expect tofind it in naturally and with its familiar associates.


4. At each evaluation, reassess the need to plant at all based on changeswhich have occurred in the meantime and the rate at which the landscapeIs recovering or deteriorating. As a general rule of thumb, it is preferable to opt forexotics removal and stabilizing bare soil over planting if there is only a limited amount oftime or labor available.

5. The following species all of which can be found persisting in urbanwoodlands are recommended for consideration in the Mid-Atlantic area:

Cano~yTrees

Red mapleSilver mapleSugar mapleRiver birchYellow birchPignut hickoryShagbark hickoryMockernut hickoryHackberryWhite ashKentucky coffee-treeBlack walnutTulip poplarSweetgumSourgumWhite oakScarlet oakSwamp white oakPin oakChestnut oakRed oakBlack oakBlack willowBasswood

(Acer rubrum)(Acer saccharinum)(Acer saccharum)(Betula nigra)(Betula lutea)(Carya glabra)(Carya oyata)(Carya tomentosa)(Celtis occidentalis)(Eraximus americana)(Gymnocladus dioica)(Juglans njgra)(Liriodendron tu!j~ifera)

(LiQuidambar styraciflua)(Nyssa sylvatica)(Quercus alba)(Quercus coccinea)(Quercus discolor)(Quercus palustris)(Quercus prinus)(Quercus rubra)(Quercus yelutjna)(Salix nigra)(Tilia americana)

Small Trees & Understory Trees

ServiceberryGray birchAmerican hornbeamWhite fringetreePagoda dogwoodFlowering dogwoodCarolina silverbellCucumber magnolia

(Amelanchier canadensis)(Betula populifolia) *(Carpinus carolina)(Chjonanthus yjrginicus)(Comus alternifolia)(Cornus florida)(Halesja carolina)(Magnolia acuminata)


Small Trees & Understory Trees (continued)

SweetbayBlack cherryHop hornbeamBlack locustSassafrasBladdernut

Shrubs

Speckled alderSmooth alderButtonbushRedbudSummersweetSilky dogwoodBlack huckleberryWinterberrySpicebushFlame azaleaPinxterSwamp azaleaShining sumacSmooth sumacStaghorn sumacAmerican elderMeadow sweetHardhackHighbush blueberryLowbush blueberryMapleleaf viburnumArrowwoodNannyberryNorthern arrowwoodYellowroot

(Magnolia yirgjnjana)(Prunus serotina)(Ostrya yjrgjniana)(Robinia pseudo-acacia)(Sassafras a1bjdum)(Staph lea tdfolia)

(Alnus jncana)(Alnus rugosa)(Cepha1anthus occjdentalis)(Cercis canadensis)(Clethra alnifolia)(Cornus amomum) *(Gaylussacia baccata)(Ilex verticillata)(Lindera benzoin)(Rhododendron calendulaceum)(Rododendron nudiflorum)(Rododendron yjscosum)(Rhus coppalina)(Rhus glabra)(Rhus typhjna)(Sambucus canadensis)(Spirea latifolia,) *(Spirea tomentosa) •(Vaccinium corymbosum) •(Vaccinium vacillans)(Viburnum acerjfolium)(Viburnum denta,tum)(Viburnum lentago)(Viburnum recognjtum)(Xanthorhiza sjmplicissima)

• Restricted to open landscapes and woodland edges

The simplest rule is to plant each species in a location most analagous to where yOU'dbe likely to find it growing naturally and with other species which would likely be itscompanions. Lastly, plant each species in a pattern that is specific to that species -- in itsown 'footprints' rather than in the more uniform on-center horticultural patterns.

There is always considerable interest in establishing evergreens, both trees and shrubs.Not only are they aesthetically appealing but they also supply winter shelter for wildlife.It is, however, important to note that very few evergreens are indigenous to the


temperate forest landscape. Air pollution which clogs the leaf's pores is especially hardon these plants which shed their leaves (needles) only every three or so years ratherthan after only eight months use. Several native species, however, do occur throughoutthe region and persist in well managed urban wildlands. Hemlock (Tsuga canadensis)is the only shade-tolerant forest canopy species, however white pine (Pinus strobus)can be established in glades and adjacent fields. Red cedar (Juniperus vjrginiana)requires very open conditions, and unlike white pine will not persist in the forest.American holly Wex opaca), inkberry Wex glabra) and laurel (Kalmia latjfolja) can beestablished in the forest shrub layer.

We strongly urge that you avoid grafted and vegetatively produced plantsinsofar as is feasible, especially for live species, with the exception of livestakes. All those patented varieties mean no genetic diversity and many plants willshow graft incapatability sooner or later. Trees grown on their own roots are far moredesirable and sturdier specimens.

Several methods of vegetation replacement are available including tramsplanting,planting balled and burlapped, bareroot, or container-grown species, establishingplants using soil bioengineering techniques, collecting and/or propagating nativespecies, as well as moving whole blocks of soil with the vegetation still intact on them.


REPLANTING STRATEGIES

Balled and burlapped (B & B) is the most common planting technique for trees andshrubs in the Northeast. Indeed, many native species which are unavailable in the tradeare those which do lli21 transplant well in this fashion such as hickories and sassafras.Although many species are available B & B, especially in larger sizes, the primarydrawback is the weight of the ball which can be a major limiting factor in woodlandrestoration. Even a relatively small tree ball can be almost impossible for two people tocarry any distance. In woodland areas where vehicular access is undesirable orunavailable, this will place severe restrictions on the use of B & B plant material.

Containerized plants are usually smaller and therefore are often more easily portaged toa forest location. Plants may be grown in the pot or be field grown and later potted incontainers. All container material should be checked for girdling roots which must be cutbefore planting. Although the plants are typically smaller, the greatest species diversityis available in containers. This method is ideal for many native species which aredifficult to transplant such as hickories and sassafras, as noted earlier, and sumac, blacklocust and black gum.

Bareroot (BR) trees are dug when dormant, usually late fall or early spring and taken toa cold storage unit where they are kept at temperatures just above freeezing and at avery high humidity. After bareroot trees are dug the soil is shaken and washed from theroots, hence the name "bareroot". Plants are only taken from storage the day they areshipped and kept moist during shipping with wet straw around the roots. Barerootplanting is a convenient method for planting large numbers of small trees at relativelylow cost, but bareroot trees have advantages beyond lower cost. Without soil aroundtheir roots, plants are lighter and therefore easier to handle.Transport is cheaper andvehicles are not always necessary to bring the material to the site. Individual trees canbe handled on site, without difficulties, by volunteers. Bareroot trees are fairly readilyavailable, but only in smaller sizes up to 2 inches in caliper only a limited number ofspecies are suitable for this planting method. Although high losses can occur withbareroot trees if they are stored, shipped or planted improperly, nearly 100% survival ispossible when larger sizes (8-10 feet) are used, and where trees are planted early in thespring and watered frequently throught the first season. Species diversities is somewhatlimited, however, so this method usually must be augmented with some B & B orcontainer plantings.

The option to collect plants for use should not be overlooked and is a very usefulmethod if appropriately undertaken. Obviously, no native habitat should be depleted oreven disturbed enough to require replanting. Nor should rare or endangered species becollected or species which are difficult to transplant. Often, however, plants are 'rescued'from an area being developed and may be relocated to analagous habitats. And whredisturbance levels are generally fairly low, some collection from elsewhere on site maybe suitable to revegetate a local disturbance. Small mats of shrubs can often be collectdquite easily.


An analagous opportunity is contracting with propagators to grow native speices, whichare otherwise unavailable. 'Plugs' of native grasses such as switchgrass (Panjcumvirgatum) and little bluestem (Andropogon scoparius) are easily produced at fairly lowcost as well as 'sods' or 'mats' of shrub and/or herbaceous communities.

Live stakes are living pieces of stems or branches taken from trees or shrubs with theability to root vigorously from cuttings. These plants, such as black willow, alder orsycamore, are generally successional plants of the lowlands and streamsides. Livestakes, although more familiarly used as part of the arsenal of bio-engineeringtechniques to stabilize an eroded bank or gully, can also be used simply to revegetatebare, open, wet areas and to accelerate the return of a wetland or floodplain to forest.

Live stakes have many of the advantages of bareroot trees, and are even easier to plant,although species diversity is even more limited. Because there is no soil, weight is notan issue. The plants are light and easy to transport, and vehicles are not alwaysnecessary to bring the stakes to the site. Since plant material used for live stakes shouldbe collected locally, the planting costs are very low, as they represent only labor andtransportion, both of which can be minimal. Unlike bareroot trees availablecommercially, almost all the plant species that will grow with this method of plantingfavor the wettest soils, providing an inexpensive method of revegetating these particularhabitats. However, some species, such as poplars, which will grow very successfullywhen planted as live stakes, survive in extremely dry habitats.


Case Study: Canopy Replacement

Stormwater runoff from a broken conduit draining an overhead highway bridge,had caused severe erosion and 1055 of vegetation in a forested stream valley within anurban wilderness park. Restoration of the canopy layer by bare root planting of nativelowland forest species was undertaken by the Friends of the Wissahickon in concertwith Andropogon. The work was carried out entirely with volunteer labor.

Before: Showing break in forest canopy where no trees or shrubs are present. This large open area was an invitationto colonization by undesirable exotics.

After: Showing replanting of the canopy trees. Although small, these trees already shade the ground andwill quickly provide a complete restoration of the closed canopy.


Photograph: Showing delivery of bare root trees to the site. Note that 120 trees can be carried by a small pick-uptrunk and handled easily by volunteers. During transportation trees were completely covered with a nylon tarpolin andtheir roots covered with wet straw. Upon arrival, trees were unloaded and stored in the shade, with their roots buriedin moist mUlch.

Photograph: Showing roots soaking in liqua-gel a water holding medium. Before planting roots are throughly coveredwith this soulution, to rehydrate roots and provide material which will release water slowly into the soil after planting.Before dipping, roots were clipped to remove any broken pieces.


Photograph: Showing trees after planting. Trees have been secured upright with a single stake, placed directlyagainst the trunk. Both stake and trunk are wrapped together from the bottom upwards with plasticized fiber treewrap. Although trees here are planted singly, they are placed no more than 4 to 6 feet apart. Other trees wereplanted in groups of 3 to 5 and placed in a single hole. Well rotted leaves were supplied by the Park System for use asmulch. Trees were watered once every two weeks by volunteers during the summer drought.


Techniques: Balled and Burlapped Tree Planting

The most common error in planting a balled and burlapped tree is to make the plantingpit too small, or too deep. It is essential that the pit should be at least 3-411 wider oneach side so that the gap around the plant's root ball can be filled with good topsoil orpeat. However, the pit bottom should be exactly the same depth as the ball so that nosettling occurs later. It is essential that the top of the root ball be at the same elevationas it was when the plant was growing in the nursery to ensure that the roots have thesame growing relationship with reference to water and air diffusion and are not subjectto the stresses involved with filling or settling. The root ball should be removed fromany supporting wire basket before planting, but the plant should be planted completewith it's biodegradable burlap wrap and supporting biodegradable twine. Once in thepit, the burlap and twine should be cut back from the top of the ball to avoid stranglingthe growth of the trunk. Excess burlap can either be cut off, or tucked into the pit andfilled over with the backfill mixturet. Tamp the soil firmly to prevent settling and toremove any large air pockets, but do not over compact. Water plant. Prune up to 1/3 ofthe foliage if necessary to reduce water stress once the plant begins to grow. This mayseem drastic, but is essential since the reduced amount of feeding roots will not beable to support a full canopy. Once the plant is firmly in the pit, it should be staked, asnoted on the diagram below, to give support and stability while the tree establishes itson root support. Once the tree has become stable, the stakes can then be removed.

~PRUNE FOLIAGE BY 1/3

,":::..,~ / WRAP TRUNK TO FI RST BRANCHES....::.... WITH COMMERCIAL TREE

WRAPPING PAPER

GUY WITH GALVANIZED IRON WI REUSE RUBBER HOSE TO PROTECTTRUNK

8' X 2" X 2" STAKES, MI NI MUMTWO PER TREE,PLACED OUTSI DEPIT, 2'INTO GROUND

TOP OF TREE BALL INSAMEPOSITION RELATIVE TO GROUNDAS IN NURSERY

FORM 3" HIGH SAUCER AND COVERWITH 2" MULCH

~;:~;>~,~~~~~~~~!::..- CUT AND REMOVE BURLAP FROM',',' BALL, ,

.';''<', UNDISTURBED SUBGRADE TREE'« ',',',',',',','"" ,'," PITS SHOULD NOT BE DEEPER

'.',',',» ',',','.'.'" THAN DEPTH OF BALL

Planting detail for a B&B tree, showing ideal planting method. Similar directions can be followed for planting B&Bshrubs.


Techniques: Bareroot Tree Planting

Ideally, bareroot trees should be planted as soon as the ground can be worked --early March in the mid-Atlantic states, to take advantage of cooler temperatures anddamper soils. Bareroot material should not be planted after the weather turns hot anddry -- this condition can occur as early as May in the mid-Atlantic states. Upon arrivalon the site, bareroot trees should be stored in the shade and their roots covered withwetted mulch, straw or compost. As the weather warms these protective measuresbecome increasingly important. Mix a wetting solution such as "Liqua-Gel" with waterto form a paste thick enough to cling to the roots. The wetting agent retains many timesits own weight of water. Before planting, clip any broken or damaged roots and dip theentire root system in this solution to rehydrate the root system and to maintain an evenmoisture balance in the soil after planting. To plant, dig a hole approximately the sizeof the spread root system. Make a small, well compacted, mound of earth in the centerof the hole and spread roots over this mound as illustrated. Backfill soil around theroots and tamp to prevent air spaces. Hold tree upright and secure with a single stakeheld against the trunk with plasticized fiber tree wrap. Mulch with rotted leaves whereavailable. If rainfall is insufficient -- less than one inch of rain a week, water newlyplanted trees at the rate of five gallons of water per tree every two weeks during thedrought. Remove stake and wrapping after one year.

PRUNE UP TO ONE THIRD OF THEFOLIAGE OR AS DI RECTED

PLACE I" X 2" WOODEN STAKENEXT TO TREE AND WRAP TRUNKAND STAKE TOGETHER WITHTREE WRAP UP TO 4'-0" HIGH

FORM SAUCER OF TOPSOIL3" HIGH AND FI LL WITHMULCH 2" DEEP

,....- ROOTS LAID OVER OVER~~~~~~ 'rzwz~~~~ ·· MOUND OF TOPSOI L BUI LT

BEfORE SETTI NG PLANT

----+~'r'---- FILL HOLE WITH TOPSOILMIXTURE WELL COMPACTED

~---UNDISTURBED SUB-GRADE

Detail: Typical bareroot tree planting.


Recommended Species

Uplands: White Oak (Quercus alba)Northern red Oak (Ouercus borealis)Sugar maple (Acer saccharum)Tulip poplar (Liriodendron tulipifera)

Lowlands: Red maple (Acer rubrum)White ash (Fraxinus americana)Pin Oak (Quercus palustris)

Nursery Suppliers

Princeton NurseriesPO Box 191Princeton New Jersey 08542(609-924-1776)

Sherman Nursery CompanyCharles City, Iowa 50616(515-228-1124)

The Buddies NurseryPO Box 14Birdsboro, Pennsylvania 19508(215-582-2410)

Products

Liqua-Gel (application rate = 4lbs. per 200 trees)E.C. GeigerBox 285, Route 63Harleysville, Pennsylvania 19438-0332

Plasticized Fiber tree Wrap (1 roll = 4"x50' application rate =1 roll per 4 trees)Phillips 66 "Duon"Blunks8923 South Octavia StreetBridgeview, Illinois 60455(312-430-2025)


Techniques: Shrub Mat Planting

Shrub mats can be collected from adjacent sites for woodland restoration wherethe existing forest canopy creates too dense a shade for the use of native grass plugsor live stakes. To collect, find an area where the shrub cover is thick enough to ensurerapid reproduction and closure of holes created. Shear tops of shrubs before diggingto reduce evapo-transporation and make handling easier. Cut a square approximately2 feet by 2 feet wide, and at least 6 to 8 inches deep, with the shovel tip. The size of amat is determined by the need to include a sufficient amount of the root systems of theplants to be moved, for these plants to survive and grow, and by the "handleability" ofeach mat. Where roots are sparse or soil sandy, larger mats will break apart whenmoved. Upon arrival on the site, mats should be stored in the shade and kept damp.After the soil has been prepared, dig hole slightly wider, but no deeper than mat to beplanted. Add a light sprinkling of peat moss and place mat in hole, replace existing soilaround mat edges and tamp carefully.lf mat supply and labor is ample, mats can bebutted together to form a continuous carpet. Otherwise, the space between each matshould be no greater than twice mat size. In event of insufficient rainfall -- less than 1inch per week -- water every two weeks for the first 2 months after installation. Ifperiods of drought occur, continue to water throughout the summer. Do not allow rillsand furrows to form as a result of watering.

SHEAR TOPS OF MATSBEFORE DIGGI NG

DIGGI NG SHRUB MATS FOR~ FOR REPAIRING BARE SPOTS

r

TYPICAL BERM SECTION

Drawing: Showing Shrub mat collection and method of planting

Success Under Stress: Managing & Restoring the Metrotorest 88

Techniques: Native Grass Planting by Plugs

Plugs of Nptive Grasses

The most effective method for establishing native grasses on bare soil is by plugswhich have been propagated from local stock. Although costly at the outset because itis so labor intensive, this method requires the least maintenance in following yearsbecause nearly complete cover is achieved in the first season. This approach is atpresent still fairly innovative and the plugs are available commercially on a very limitedbasis. For large area plantings, it is advisable to contract directly with a propagator toobtain adequate supplies at a reasonable price. Arrangements should be made tocontract grow this plant material in the fall prior to spring installation. Two-year-oldplugs of little bluestem (Andropogon scoparius) in peat pots 2" in diameter and 2.5"deep currently being supplied to the National Park Service by North Creek Nurseries,RR #2, box 33, Landenburg PA 19350; telephone: (215) 255-0100; contact: DaleHendricks.

Plugs can be seedling grown, or propagated from divisions from "reserved" nativegrass populations. Collect plants large enough to provide an economical number ofplugs, but not so large as to be overgrown and dead inside, approximately 8 inches indiameter, 10 to 30 plugs can be grown from each original plant. Collect stock in earlyspring before the ground warms and the top growth is still dormant. Plants can bestored for long periods of time, but care must be taken at all times to insure that theroots of the stored plants do not dry out. Cover collected plants with moist burlap andstore in the shade until ready to divide. Wash the dirt from the root system, trim theroots and shoots to 1 inch in length, and separate the plant into small pieces -- one bigshoot per piece. Set pieces into rooting medium and grow in a greenhouse, in aplastic liner tray in 2 x 1-1/2 inch cubes. Water plants to surround roots and wash outair pockets. Keep soil moist until root growth begins. Cuttings should grow for aminimum of 12 to 16 weeks to ensure a root bound plug. Remove the plugs from thecubes and plant in the same manner as conventional potted perennials. Nativegrasses are warm weather plants and begin their growing cycle in early summer, soplugs should be planted when the soil is warm enough to get good root growth -- latespring (April/May). Fall planting is not advised because of the likelihood offrost-heaving. Do not allow rills and furrows to form as a result of watering.

Planting should be undertaken with a tree planting bar at one-foot on-center spacing .Insure soil is firmed around each plant and then mulch to a depth of 2" with weed-free,seed-free, unrotted clean straw. Barley, wheat, or rice straw is acceptable. In event ofinsufficient rainfall -- less than 1 inch per week -- water every two weeks for the first 2months after installation. If periods of drought occur, continue to water throughout thesummer. Where honeysuckle or invasive exotics were eradicated before planting,continued weeding is required.

89Success Under Stress: Managing & Restoring the Metroforest

Techniques: Live Stake Planting

Live stakes must be cut when the plants are dormant, from December to March andplanted no later than one day after collection. Survival rates will be increased if thestakes are planted the same day they are cut. Live stakes should be cut from livingstems or branches and should be approximately 1/2 inch to 1-1/2 inches in diameterand 2 to 2-1/2 feet long. Cuttings should have at least two bud scars near the top of thestake to facilitate the growth of new branches. When preparing the stake, remove theside branches cleanly and preserve the bark intact. The top of the stake should be cutoff square to provide a flat surface for tamping into the soil and the thicker end, at thebottom, should be cut into a point for easy insertion. Upon arrival at the site, live stakesmust be kept fresh and moist -- stored in the shade with their roots covered withwetted mulch, such as straw or compost, to reduce dehydration. Under nocircumstances should live-stake plants be left uncovered to bake in the sun beforeplanting. To plant. pound four-fifths of the length of the stake into the ground with adead blow hammer. A dead blow hammer is a hammer with a hollow head filled withshot, and is used to minimize splitting at the head of the stake.The stake should beplaced shoot end up (buds pointed up), root end down. Correct installation is critical -an upside down stake will not grow. Regardless of the steepness of the terrain, livestakes should be positioned at a 45 degree angle to the ground plane, to increaserooting surface. After hammering the stake into the soil, compact soil firmly around thestake where loose.

SEVERAL STAKESCAN BE HARVESTEDFROM EACH STEM

./!'~ LEAVE AT LEAST

TWO BUD SCARS

;,t ----- 1/2" TO 1 1/2-J DIAMETER

\ROOT END -- USUALLYTHICKER -- CUT END IN POINT

SHOOT END -- USUALLY THINNERBUDS POINT UP -- CUT END SQUARE

~

Drawing: Showing the harvesting and preparing of live stakes.


LIVE ST AKES ROOTED AND SPROU·

LIVE STAKES ON~FLAT AREA ~

-~~~~-/

LIVE STAKESIN BANK

\TAKESS::::L: BE PLANTED AT AMINIMUM /OF TWO FEET ON CENTER IN A STAGGERED PATTERN

POSITION STAKES AT 45 DEGREESTO GROUND PLANE

Drawing: Showing live stake installation

Photograph: Showing a live stake removed from the ground after six weeks in order to evaluate growth. Roots aregrowing on all buried portions of the stake, with the longest roots found at the bottom of the stake.


HABITAT CORRIDOR NETWORKS

While this report has focused on the management of woodland areas, what occurs in theadjacent landscapes also impacts these sites. No landscape functions independently ofits surroundings. In a remnant natural area, disturbance is typically severe at the edgesand many sources of stress, such as the spread of exotics, frequently enter from theedges. Large entrenched areas of knotweed, for example, immediately adjacent to thewoodlands will spread and continuously require monitoring and maintenance.

More subtle, but just as important, are positive impacts stemming from adjacentlandscapes. It has long been documented that diversity diminishes in landsapefragments which are isolated from larger areas of natural habitat. Very positive benefitsto each of the woodlands and the wildlife they support could be provided by establishinga network of habitat corridors connecting the woodlands to each other as well as toother more natural areas in a park, such as ponds and wetlands and wildflowermeadows. The following general guidelines are recommended:

1. Provide a continuous corridor of layered forest vegetation with canopy, understory,shrub, and ground layer plants connecting the woodland areas.

2. The corridors should be no less than 300 feet wide wherever possible, but insmaller systems, narrower corridors of say 100' are preferable to none at all.

3. A corridor margin of early successional vegetation is recommended, including bothshrubs and herbaceous landscapes.

4. Wherever forest vegetation is not feasible, meadows of native tall grasses andwildflowers with occasional native shrub clumps are preferable to turf as theconnecting piece.

5. Multilayered plantings of horticultural species are also preferable to turf, as long asnone of the species is a naturalizing exotic which might run rampant in the lessintensively managed woodlands. As replanting is required in these areas, nativeforest species should gradually be favored over exotics.

6. Species requiring routine pesticide management should be removed from thewildlife corridors and replaced with native species.

7. Exotic invasives should be vigorously controlled in the wildlife areas and be givenhigher priority than elsewhere, except the woodlands themselves.


8. Deadwood, both standing snags and fallen logs, is important in the corridors andshould be left in place wherever possible.

9. Contact with human use and high levels of activity should be minimized andshould influence the siting of the corridors. Proximity to active recreation and majorwalkways should be avoided wherever possible.

10. A 300-foot margin around each of the woodland areas should also be managed aspart of the habitat corridor system. Exotics control is especially critical here.Similarly, native plant community types found at earlier stages of succession, fromshrublands to native meadows, are desirable.

11. Appropriate signage to designate the habitat corridor is also recommended andwill help alert the visitor to the fragile and vulnerable nature of sanctuaries, andestablish a more respectful attitude before arrival at the restored woodlands.

12. It is preferable that a pond have a soft vegetated edge wherever its margin meetsthe corridor network. Where this is not presently the case and only a paved edge isavailable, large tubs of native aquatic vegetation should be placed in the ponditself. These tubs can be set on boulders to achieve the appropriate water depth.Appropriate species include sweet-scented water lily (Nymphaea odorata),bullhead lily (Nuphar yarjegatum), arrowhead (Sagjttada latjfolia), pickerel weed(Pontederia cordata), and blue-flag iris (Iris versicolor), among others.

In addition, dense thickets of native wetland shrub species, such as sweetpepperbush (Clethra alnjfolia), buttonbush (Cephalanthus occidentalis), highbushblueberry (Vaccinium corymbosum), winterberry (Ilex verticjllata), and waxmyrtle(Myrica cerifera), can also be planted in larger boxes set in the pond edge wherethey will be protected from human disturbance. As these species also tolerate drierconditions, additional plantings in the adjacent uplands will enhance the vegetatedcorridor and should be augmented with groves and thickets of lowland trees, suchas tupelo (Nyssa sylyatjca), walnut (Juglans nigra), butternut (Juglans cjnerea),sweetbay magnolia (Magnolia virginiana), and speckled alder (Alnus rugosa).

13. Additional wetland habitat can, in places, be created by storing stormwater runoff indepressions and swales in the habitat corridors. For example, where a low-lyingturf area is being converted to meadow to complete a missing link in the corridornetwork, it may be desirable to regrade the area to trap and retain runoff to createan intermittent wetland, either herbaceous or woody.

14. Small stands of evergreen vegetation should be established at reasonableintervals along the corridor's length averaging no more than 300-500 feet apart.Species suitable beneath forested canopy include hemlock (Tsuga canadensis),American holly Wex opaca), inkberry (Ilex glabra), and laurel (Kalmia latjfolia).


White pine (Pjnus strobus) and red cedar (Juniperus vjrgjnjana) require more openlandscapes to become established and can be used in meadow areas.

15. Native vines are especially desirable in the habitat corridors. Virginia creeper(Parthenocissus guinguefolia), grape (Vitis spp.), poison ivy (Rhus radicans), andcatbrier (Smilax spp.) are all high value wildlife foods and the latter two also helpdiscourage pedestrian traffic.

16. The landscape character of the habitat corridor network should be integrated withthe overall design character of a park and should not conflict with other scenicand aesthetic goals. These are managed landscapes, not simply areas wherenature is left to run wild, and a naturalistic character compatible with itssurroundings is desirable.


RECOMMENDED READING LIST

PLANT ECOLOGY, HUMAN ECOLOGY &GENERAL ECOLOGY

Changes in the LandWilliam CrononHill and Wang, New York, 1984

Communities and EcosystemsRobert H. WhittakerMacmillan Co., New York, 1975

Deciduous Forests of Eastern North AmericaE. Lucy BrownHafner Press, New York 1974

EcologyRobert E. RicklefsChiron Press, Portland, 1973

The Ecology of Invasions by Plants & AnimalsCharles EltonMethuen & Company, Ltd., London, 1958

Fire in America: A Cultural History of Wildland and Rural FireStephen T. PynePrinceton University Press, Princeton, 1982

Fundamentals of EcologyEugene P. OdumW.B. Sanders Company, Philadelphia, 1971

Landscape EcologyRichard T.T. Forman & Michel GodranJohn Wiley & Sons, New York, 1986

The Life of the ForestJack McCormickOur Living World of Nature SeriesMcGraw Hill, New York, 1966


Man in Adaptlon: The Cultural PresentYehudi CohenAldine Publishing Co., Chicago,1968

Man's Role In Changing the Face of the EarthVolumes I and IIeds. Sauer, Bates, MumfordUniversity of Chicago Press, Chicago, 1956

The Natural Gardens of North CarolinaB.W. WellsUniversity of North Carolina Press, Chapel Hill, 1967

The Natural Geography of PlantsHenry A. Gleason and Arthur ConquistColumbia University Press, New York, 1964

The Oxford Book of TreesA.A. Clapham and B.E. NicholsonOxford University Press, London,1975

pine Barrens: Ecosystem and LandscapeRichard FormanAcademic Press, New York 1979

Reading the Landscape: An Adventure in EcologyMay Theilgaard WattsMacmillan Co., New York, 1963

Rebuilding Central Park: A Management & Restoration PlanCentral Park ConservancyThe Arsenal830 Fifth Avenue, Room 103New York NY 10021

Vegetation of New JerseyBeryl Robichaud and Murray BuellRutgers University Press, New Brunswick, 1973


MAGAZINES

Landscape Joyrnaleds. Darrel Morrison/Arnold AlanenUniversity of Wisconsin Press, Madison, 1981

Natural Areas JoyrnalPub. Natural Areas Association320 South 3rd StreetRockford IL 61104

Restoration & Management Notesed. William R. Jordan IIIUniversity of Wisconsin Press, Madison, 1983

PLANNING, DESIGN & VEGETATION MANAGEMENT

Art into Landscape. Landscape into ArtA.E. ByePDA Publishing Co.Mesa Arizona, 1983

Bioengineerjng for Land Reclamation and ConservationHugo SchiechtlUniversity of Alberta PressAlberta, Canada, 1950

Design With NatureIan L. McHargThe Natural History PressGarden City, New York, 1969

Garden DesignPeter ShepherdDesign Center PublicationMcDonald & Company, Ltd., London, 1969

The Granite GardenAnne Whiston SpiroBasic Books Inc.New York,1984


The Making of the English LandscapeHoskinsPenguin Paperback

The New Jerusalem. Planning and politicsArther KutcherThames and Hudson ltd. , London, 1973

New Lives. New LandscapesNan FairbrotherAlfred Knopf, New York, 1970

The Oldest Road. An Exploration of the RidgewayJRL Anderson and Fay GoodwinWildwood House, London, 1975

The Oregon ExperimentAlexander, Silverstein, Angel, Ishikawa and AbramsOxford University Press, New York, 1975

A Pattern Language: Towns - Buildings - ConstructionAlexander, Ishikawa, Silverstein, etc.Oxford University Press, New York, 1977

TownscapeGordon CullenReinhold publishing Corp., New York, 1961

PHILOSOPHY

The Aquarian Conspiracy: Personal & Social Transformation in the 1980'sMarilyn FergusonJ.P. Tarcher, Inc., Los Angelos, 1980

Earth Keeping: Christian Stewardship of Natural Resourcesed. Loren WilkinsonWm. Eerdmans Publishing CompanyGrand rapids, Michigan,1981

Love & Death In the American NovelLeslie FiedlerCriterian Books, New York, 1960


Nature and MadnessPaul ShepheardSierra Club BooksSan Francisco, 1982

Speaking for NaturePaul BrooksHoughton Mifflin Co.Boston, 1980

The Subversive Science: Essays Towards an Ecology of Maned. Paul Shepard and David McKinleyHoughton Mifflin Co., Boston, 1964

The Turning Point: Science. Society &The Rise in CultureFritjof CapraSimon &Schuster, New York, 1982

The Uses of Enchantment: The Meaning & Importance of Fairy TalesBruno BettelheimAlfred Knopf, New York, 1976

DRAWING

Drawing: The Natural Way to DrawKimon NicolaidesHoughton Mifflin Company, Boston, 1941

Drawing on the Right Side of The BrainBetty EdwardsJ.P. Tarcher, Inc., Los Angelos, 1979

PLANT IDENTIFICATION

A Field Guide to the FernsBoughton CobbHoughton Mifflin Co., Boston, 1956

Grasses: An Identification GuideLauren BrownHoughton Mifflin Company, Boston, 1979

Success Under Stress: Managing & Restoring the Metroforest 9.9

Ground Covers for Easier GardeningDaniel FoleyDover, New York, 1961

Manyal of Woody PlantsMichael A. DirrStipes Publishing CompanyChampaign, Illinois, 1975

Native Trees, Shrybs and Vines for Urban & Rural AmericanGary L. HightshoeVan Nostrand Reinhold Co., New York, 1988

The Tree Identification Book and The Shrub Identification BookGeorge W. D. SymondsWm. Morrow, Co., New York, 1958


Success Under Stress: Managing and Restoring the Metroforest

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Transcript of Success Under Stress: Managing and Restoring the Metroforest