...Using Science to Benefit Golf

Turfgrass and EnvironmentalResearch Online

Volume 3, Number 7April 1, 2004

Colbert Hills Golf Course near Kansas State University servesas an excellent example to a apply a versatile, simplified, sci-ence-based system for making environmental quality assess-ments and linking outcomes to remedial management.

PURPOSE

The purpose of USGA Turfgrass and Environmental Research Online is to effectively communicate the results ofresearch projects funded under USGA’s Turfgrass and Environmental Research Program to all who can benefitfrom such knowledge. Since 1983, the USGA has funded more than 290 projects at a cost of $25 million. The pri-vate, non-profit research program provides funding opportunities to university faculty interested in working on envi-ronmental and turf management problems affecting golf courses. The outstanding playing conditions of today’sgolf courses are a direct result of using science to benefit golf.

Editor

Jeff Nus, Ph.D.904 Highland DriveLawrence, KS 66044jnus@usga.org(785) 832-2300(785) 832-9265 (fax)

Research Director

Michael P. Kenna, Ph.D.P.O. Box 2227Stillwater, OK 74076mkenna@usga.org(405) 743-3900(405) 743-3910 (fax)

Permission to reproduce articles or material in the USGA Turfgrass and Environmental Research Online (ISSN 1541-0277) isgranted to newspapers, periodicals, and educational institutions (unless specifically noted otherwise). Credit must be given tothe author(s), the article title, and USGA Turfgrass and Environmental Research Online including issue and number. Copyrightprotection must be afforded. To reprint material in other media, written permission must be obtained fom the USGA. In anycase, neither articles nor other material may be copied or used for any advertising, promotion, or commercial purposes.

USGA Turfgrass and Environmental Research Committee

Bruce Richards, ChairmanJulie Dionne, Ph.D.

Ron DodsonKimberly Erusha, Ph.D.

Ali Harivandi, Ph.D.Michael P. Kenna, Ph.D.

Jeff Krans, Ph.D.Pete Landschoot, Ph.D.

James MooreScott E. Niven, CGCS

Jeff Nus, Ph.D.Paul Rieke, Ph.D.

James T. SnowClark Throssell, Ph.D.

Pat Vittum, Ph.D.Scott Warnke, Ph.D.

James Watson, Ph.D.

Golf is one of the fastest growing industriesin the United States, yet its environmental impactis largely unknown. Somewhere in the UnitedStates, on average, more than one new golf courseopens every day (509 new courses opened in1999)(12). The 26.4 million U.S. golfers play atmore than 16,743 (12) courses that occupy wellover 3 million acres. The annual impact of thegolf industry on the U.S. economy was estimated

at $30 billion in 1998 and is growing (12). Withthe international golfing scene adding significant-ly to these numbers, both the golf industry and thepublic are interested in the impact of golf on theenvironment.

Golf courses provide unique settings forenvironmental studies. They typically containsegments progressing from high input zones torelatively undisturbed natural settings. Also, man-agement inputs are commonly well-documented.Researchers studying golf-related environmentalissues find a receptive audience of superintend-ents through avenues like the United States GolfAssociation’s (USGA) Green Section Record (14)and the publications and educational programs ofthe Golf Course Superintendents Association ofAmerica (GCSSA)(7). Contrary to popular belief,

A Multiple Index Environmental Quality Evaluation and Management System:Application to a Golf Course.

Steve Thien, Steve Starrett, Robert Robel, Patick Shea, Dave Gourlay, and Cal Roth

SUMMARY

A method for evaluating environmental quality of large-scale landscapes that bridges scientific research and publicuse is in great demand. Resource managers, industry andcommunity planners, government policy-makers, and sci-entists all support an improved environment, but connec-tions between processes, remediation, and managementaren't always readily available or understandable to such adiverse community. This paper describes a versatile, sim-plified, science-based system for making environmentalquality assessments and linking outcomes to remedial management.

This complex goal becomes attainable by: establishmentand use of appropriate scientific databanks, determinationof targets for acceptable and unacceptable impact on criti-cal ecosystem functions, simplified visual integration ofmany indicators, and linkage to management databases.

The process is being developed by a multi-disciplinarystudy of a grassland ecosystem converted for use as a golfcourse.

The system can be easily customized to local conditionsand has wide-range application to many types of naturaland managed ecosystems.

STEVE THIEN, Ph.D., Professor of Soil Science, Department ofAgronomy, Kansas State University, Manhattan, KS; STEVESTARRETT, Ph.D., Assistant Professor of Civil Engineering,Kansas State University, Manhattan, KS; ROBERT ROBEL,Ph.D., Professor of Biology, Kansas State University, Manhattan,KS; PATRICK SHEA, U.S. Department of Interior; DAVEGOURLAY, CGCS, Director of Golf Operations, Colbert HillsGolf Course, Manhattan, KS; CAL ROTH, Agronomist, PGATOUR Golf Course Operations.

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Figure 1. The 13th hole at Colbert Hills golf course,Manhattan, Kansas, during construction shows the nativetallgrass prairie site. A team of researchers at Kansas StateUniversity characterized the original conditions of the naturalecosystem and has been monitoring the same environmen-tal indicators during and after construction. The public, thegolfing industry, and many other entities want informationabout how courses impact the environment. Golf coursesuperintendents can use the environmental quality assess-ment system described here to guide their managementtoward targeted goals. (Photo courtesy of Dan Donnert,KSU Photographic Services)

USGA Turfgrass and Environmental Research Online 3(7):1-10.TGIF Record Number: 97541

evidence from these sources, and others, is build-ing that golf courses, with their combination ofplant communities, open expanses, and naturalareas can be an accommodating habitat for birds,animals, pollinators, fish, amphibians and otherfauna and flora (1, 2, 9). There remains, though,a great need to translate research into workingmanagement tools for the betterment of golfcourse ecosystems. Golf courses present, per-haps, one of the best living laboratories for thesystematic study and monitoring of environmentalquality from which the improvement of other nat-ural, large-scale ecosystems can be modeled.

In Quest of Quality

Both the scientific community and thepublic support practices that improve the environ-ment. Given the world's collective knowledge,abilities, interests, and support, one could reason-ably expect our modern society to have developeda more sustainable, less destructive, interactionwith its environment. The fact that we haven't istroubling; however, there is the opportunity forchanneling these mutual interests into a processand resulting solution.

Gifford Pinchot (6) and Frederick LawOlmstead (5), at the end of the nineteenth century,championed the systematic and scientific manage-ment of large-scale landscapes. They coupledemerging ecological sciences, like botany and sil-viculture, to traditional biological sciences. Bytoday's standards, their tools were primitive, yetthey may have taught us the value of "looking atthe whole forest, and not just single trees."

In the modern era of powerful, molecular-level technology, a case could be made that thescientific community can describe to the publicmore than it wants to know about a particular tree,or molecule of the tree's genome. However, thedescription often stops short of any effort todescribe the forest. Large databases exist thatdescribe scientific aspects of our environment,but most await translation into workable manage-ment tools. At the beginning of the 21st Century,a holistic, scientific-based, public-friendly methodfor evaluating and managing the relative health of

large-scale landscapes seems like the missing linkin environmental improvement.

Government, industry, university, andpublic entities have a continuing interest in a vari-ety of ecosystems. Frequently, their interest is inan appropriate management regime to establish ormaintain a quality environment. The phrase,"quality environment" is vague and susceptible toconflicting interpretations. Too often, environ-mental quality is touted as a goal, but one typical-ly lacking an itinerary, roadmap, or destinationand, therefore, of little practical use.

Although scientists lean toward character-izing the environment through quantifying andinterpreting large numbers of indicators, theresulting set of isolated indices falls short ofdescribing the forest (or the "big picture"), partic-ularly for the non-scientist. Alternatively, con-densing many indices into a single index intro-duces significant theoretical and practical short-comings. This article describes a utilitarian con-nection between the evaluative and managementsegments of environmental quality. The articlesuggests how, by appropriately combining man-agement strategies with environmental databases,environmental quality can be changed from anempty idea into a workable tool, leading to sus-tained environmental improvement. Thisapproach might best be viewed as "looking at sin-gle trees to see the whole forest." We'll demon-strate this concept using a golf course as our liv-ing laboratory, but the system's versatility allowsits use on practically any ecosystem.

Golf on the Grasslands and EnvironmentalResearch

During 1999-2000, Colbert Hills GolfCourse was constructed on a 312-acre nativegrassland site near Manhattan, Kansas (Figure 1).Soils, water resources, flora, and fauna on this siterepresent a natural Kansas tallgrass prairie ecosys-tem. Environmental researchers at nearby KansasState University were presented an excellentopportunity to study the impact a golf course hason the environment. Prior to construction on the

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site, researchers collected baseline data on envi-ronmental indicators selected to describe originalconditions of the native grassland ecosystem. Asarchitectural plans were being finalized, thecourse superintendent assisted in the selection ofresearch sites and indicators. Water quality, soilquality, turf management, grassland ecosystems,avian ecosystems, aquatic ecosystems, and insectecosystems were studied. Subsequent measure-ment of the same indicators has progressedthrough construction and, now, operation and useof the course. This project represents, perhaps, themost extensive environmental research evaluationever conducted on a golf course.

Coupling with the research team, thecourse superintendent, an agronomist from thePGA TOUR golf course properties, and a scientistfrom the United States Department of Interiorhave used the Colbert Hills project to develop amultiple indexing system to gauge the environ-mental quality of the golf course. Named theColbert-Thien (pronounced "teen") Environmen-tal and Evaluation Management system, CTEEMis a versatile, informative, simplified, science-based method for identifying environmentalprocesses in need of remediation and a source ofmanagement strategies to apply toward improvingthose conditions.

With this research, we're attempting todetermine the ecological impact of converting anative grassland site to a golf course. We also aimto develop guidelines useful to the golfing indus-try for minimizing and remediating any negativeenvironmental impacts of golf course construc-tion, operation, and use.

Methodology

As described earlier, characterizingecosystems requires both data and interpretation.Using today's technology, scientists can measure alarge number of indices; so many, however, thatthey can often be confusing to the non-scientist.Alternatively, reducing many indices to a singleindex has theoretical shortcomings and practicallimits associated with over-simplification of inter-

pretations. The CTEEM system overcomes both of

these limitations by coupling multiple indicesfrom a large-scale landscape into an easily under-stood visual gauge of environmental quality. Bylinking the identification of degraded processesand remediation guidelines, the CTEEM systemcomprises a complete environmental assessmentand management package.

A soon-to-be developed urban area adja-cent to the golf course will add a new dimensionto our monitoring activities. The flexibility of theenvironmental evaluation model described herelends promise to its use as a prototype for appli-cation to practically any size or type of ecosystem.For continued comparison of change from originalgrassland conditions, the researchers have avail-able some undisturbed sites on the Colbert Hillsproperty and databanks from the Konza Prairie, aNational Science Foundation designated Long-Term Ecological Research (NSF-LTER) site (10).Both the Konza Prairie and Colbert Hills sites arerepresentative of the native tallgrass prairie in theFlint Hills of eastern Kansas and physically existwithin a few miles of each other.

Environmental quality, in its simplestform, is an assessment of essential ecosystemfunctions. The CTEEM system blends existingtechnologies to identify, monitor, assess, illustrate,and offer management strategies for any numberof environmental quality indicators in an easy-to-understand format. First, essential functions andtheir measurable indicators are identified andmonitored. Data from individual indicators arethen graphed on control charts where sustainableranges have been identified. Next, control chartindices are logically grouped and illustrated in a"spider radar" graph where environmental indica-tors outside of sustainable limits are easily detect-ed. Finally, managers can access options forremediating degraded indicators.

Steps necessary for implementing theCTEEM system are:

Identify critical functions of an ecosystem.Each ecosystem can be subdivided into naturalfunctions (reactions, processes, and/or cycles)

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critical to sustaining that ecosystem. Ecologicalsciences can provide valuable guidance in select-ing the functions most reflective of the ecosystemunder study. Primary functions in an ecosystemcan be further broken into subsystems. For exam-ple, in the grassland/golf turf ecosystem currentlyunder study, soils are assigned critical functions inplant growth, soil tilth, environmental buffering,soil life, and natural cycling functions (13).Within the natural cycling category, carbonsequestration in soil might be one critical functionselected for evaluation because of its impact on somany soil properties.

Select appropriate indicators to evaluate thesefunctions. Several indicators may be necessary toadequately assess each function. Then again, oneindicator may be useful in evaluating severalfunctions. The scientific literature provides awealthy repository of potential indicators. Thegreat diversity in golf courses and scope of theevaluation can both be accommodated in this stepby customizing the indicator selection to localconditions. Care should be taken to identify a list

that is informative, measurable, and economicallyfeasible. In keeping with the previous example,one indicator of carbon sequestration might besoil organic matter (SOM) content.

Measure indicator status. Technology has pro-vided access to rapid and comprehensive analysesfor most needs. In some cases, modern or historicdatabases can provide essential information.Measurement frequency will be indicator-depend-ent. With some, annual or seasonal testing will besufficient, while others may be automated to sam-ple on shorter intervals. Some measurements maybe linked to monitor specific episodes (rainfallevents, chemical applications, managementchanges, etc.). For this example, commercial test-ing laboratories routinely provide analysis of soilsamples for organic matter content.

Establish control chart indices (Fig. 2).Control charts offer an informative method ofcomparing indicator measurements to ranges thatdelimit sustainable and degrading conditions (11).The key to using control charts lies in settingappropriate and acceptable target boundaries thatdelineate sustainability and degradation. In somecases only minimum or maximum boundariesmay be appropriate. Control limits can be estab-lished with the assistance of state extension serv-ices, literature surveys, management experience,model predictions, consultants, regulations, orother sources. For this example, a minimum SOMcontent of 1% might be selected as a lower controllimit for some soils based on diminished soil tilthor water holding capacity at lower levels. Whilehigh SOM is edaphologically desirable, maintain-ing organic matter content above 3% may proveeconomically unfeasible on many soils and socould establish an upper control limit.

Transform multiple indices into environmen-tal quality evaluation graphs (Fig. 3). In thisstep, indices from any number of quality controlcharts are normalized onto a "spider radar" graph.This format produces an easy-to-understand, visu-al representation of environmental quality. Ahigh quality ecosystem exhibits a nearly circular

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Figure 2. Evaluating environmental quality requires meas-uring indicators of critical ecological functions over time.These values are modeled onto control charts where testvalues are plotted on a time line. Superimposed on the con-trol chart are upper (UCL) and lower (LCL) control limitsbased on known or desired tolerances of degradation.Values between the UCL and LCL would then represent asustainable condition. Indicators that fall outside the sus-tainable range would signal a need for targeted remediation.Each indicator used for assessing an ecosystem would bemodeled onto a control chart.

"radar" image with all indicators falling in the sus-tainable range. When some indicators fall outsidethe sustainable range the circular "radar' imagebecomes skewed. The cause of degradation (i.e.which indicator) and its severity (i.e. amount ofskewing) are readily apparent based on irregulari-

ty in the diagram's form. Alternatively, a circularform could denote a severely degraded environ-ment if all indicators lie outside the sustainablelimits.

Appropriate computerization can rendereither an episodic event or be animated for a sys-

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Figure 3. An environmental quality evaluation spider radar graph illustrates how well multiple indices conform to the limits ofthat indicator's sustainable range (as identified with control charts like those in Figure 2, 3 and 5). Indices (purple dots) that liewithin their target range (zone between the red lines) show ecosystem indicators operating in a sustainable mode. Indices lyingoutside their target range, either too high or too low, represent degradation. Only soil porosity and total nitrogen concentrationin water represent site conditions, the other indices shown on this example do not represent actual data. A high quality ecosys-tem would show a nearly perfect radar circle (colored area outlined by purple dots) within the sustainable range. Degradedfunctions lie outside the sustainable range and skew the radarcircle. Outer arcs group indicators into management areas (soil,water, fauna, and flora quality).

tematic view of environmental quality changesover time. The compliance of an individual indexto boundary conditions over time can also beviewed. This flexibility allows users to track thestatus of either an individual indicator or an arrayof indicators in response to natural cycles, cata-strophic events, or normal managed inputs.

Select appropriate remedial management fordegraded indicators. In the CTEEM system,evaluation graphs summarize which indicators(and hence, which ecosystem functions) lie out-side their assigned sustainable limits and are con-tributing towards the degradation of the ecosys-tem. The obvious next step is to computerizelinks from these indicators to a remediation data-bank or website where appropriate managementsteps for improving the environment can be sug-gested. That step is currently in development.

Monitor indicators over time. Long-term mon-itoring of essential indicators will illustrate howenvironmental quality responds to natural disrup-tive events or management programs.

These seven steps in the CTEEM systempresent a conceptual scheme for implementing anenvironmental quality evaluation and manage-ment program. It is currently being applied to agrassland ecosystem where portions have beenconverted into a golf course, but the principles areapplicable to a host of ecosystems on practicallyany scale. Any phase that harbors some shortagesof information, procedures, and/or recommenda-tions exposes future research needs. Currently, alltechnologies necessary for implementing this pro-gram are available from a variety of sources.Maximum utility of the CTEEM system will comewith future development of computer capability tomesh input and output information. We believethe process has extended application and can havea significant impact on global environmental eval-uation, management, and upgrading.

Application of the CTEEM system to a golfcourse

The golf course industry seeks to be envi-ronmentally responsible. The burden of meetingthis responsibility often falls on the golf course

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Figure 4. Control chart for soil porosity, an indicator of soil quality. Soil porosity was within the acceptable range prior to con-struction (Sep-98), but fell below acceptability during construction (Oct-99). Some sod establishment problems were evident.After one winter of freezing-thawing and wetting-drying, porosity returned to the acceptable range (May-00).

superintendent, individuals highly skilled in turfmanagement, but not typically trained as ecologi-cal scientists. Superintendents already evaluateagronomic indicators on a regular schedule, soadapting to an environmental monitoring programshould involve familiar practices. Some may,however, be served by technical education and/orconsultation in selecting appropriate evaluationcriteria, methods and target control levels; meet-ing local compliance requirements; databasedevelopment and matching remediation options toenvironmental indicators. Both the GCSAA andUSGA have educational and published resourcesthat can meet that demand. The CTEEM systemprovides the framework these managers need tomake environmental stewardship monitoring justas routine as their current agronomic monitoring.It describes environmental evaluation as a series

of steps that are easily customized to individualcourses. By adopting an environmental evalua-tion program, superintendents can identifyingproblem areas, be guided toward remediation, anddemonstrate progress toward sustainability.

To illustrate how the CTEEM system isbeing applied to Colbert Hills Golf Course, wehave included examples from the soil quality,water quality, and avian ecosystems work inprogress.

Soil Quality Example

Movement of air and water into andthroughout the soil body easily qualifies as oneindicator of critical soil functions like plantgrowth, optimum microbial activity, and watercycling, to name a few. Soil porosity, or the non-

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Figure 5. A control chart for daily average of total nitrogen concentrations in runoff water on episodic days in April, May, andJune, 1999 for Little Kitten Creek where it exits and enters Colbert Hills Golf Course. The upper control limit (UCL) is set at 3mg L-1.

solid volumetric percentage, is one measure ofthis redistributive process. Porosity can be calcu-lated from soil bulk density, or volumetric mass,which is an easily measured property.

The USGA (8) recommends that sand-based golf green rootzones have a porositybetween 35 and 55 percent. Finer-textured fair-way soils typically have a narrower porosity rangein which plant growth is optimized, making arange of 40 to 50 percent porosity our target LCLand UCL for fairway and rough regions. Theselatter limits correspond to values of 1.59 g cm-3

and 1.33 g cm-3, respectively, on the control chart

for bulk density (Figure 4). Data show that bulkdensity was within the sustainable range prior toconstruction, but rose into the degraded range dur-ing construction (note that a rise in bulk densitycauses a fall in porosity). At this stage, this indi-cator would skew the soil quality segment of thespider radar graph (Figure 3) and alert the super-intendent to apply some management strategy,perhaps selecting core aeration based on experi-ence, or accessing an available database or linkedwebsite for additional options. Further monitoringwould determine the effectiveness of the applied management.

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Figure 6. A spider radar graph displaying daily average of total nitrogen concentrations in runoff water onepisodic days in April, May and June, 1999 where Little Kitten Creek exits Colbert Hills Golf Course. Theupper control limit (larger red circle) is set at 3 mg L-1 and the lower control limit (smaller red circle) is setat 0 mg L-1.

Water Quality Example

Several physical and chemical indicatorsrelate surface-water quality to stream life, biolog-ical diversity, and suitability for conversion tohuman consumption. One indicator monitored inthis study was the total-nitrogen concentration.Nitrogen occurs in various forms in soil, plantresidue, and wildlife excrement. It is commonlyapplied to turfgrass to stimulate growth. Federalregulations are in the planning to establish nutri-ent criteria in streams that would minimize theadverse effects on humans, livestock, and aquaticlife (3). At this point, we have adopted our lowestdetection level (shown as zero on graphs) as theLCL and set the total-nitrogen UCL at 3 mg/L forthis water quality indicator (3, 4).

Between April and June 1999, surfacewater leaving Colbert Hills Golf Course exceededthe UCL six times (Figure 5). The surface waterentering the Colbert Hills site did not exceed theUCL. An increasing index, or one that exceedsthe UCL, alerts the superintendent to evaluatemanagement activities that might be a contributo-ry cause. Suggestions linked to excessive nitrogenlevels may include fertilizer rate adjustment,change in fertilizer form, timing of application,widening of buffer zones around surface waterbodies, etc. Course construction was occurringbetween April and June 1999, so much of the timethe soil surface was bare in preparation for sod-ding. It’s likely that the excessive nitrogenobserved in the stream was a result of erosionassociated with the unprotected soil surface (15).

Viewed with other indicators on the com-posite spider radar graph (Fig. 3), total nitrogen inthe surface water for this date skews the radarimages (i.e. lies outside of the sustainable range)and would need remedial management. Spiderradar graphs can also show a time sequence ofdata for a single indicator (Figure 6). In this case,some total nitrogen levels in stream water fall out-side of the control zone and produce some skew-ing of the radar image over the times indicated.This condition would signal an indicator in needof remedial management and the cause may belinked to other dated episodes.

Avian and Mammal Ecosystems

The quality of wildlife habitat is beingassessed with Habitat Suitability Index (HSI)models (16). Developed by the U.S. Fish andWildlife Service and applied to hundreds ofspecies, HSI models quantify relationshipsbetween key environmental variables and habitatsuitability for a target species. HSI models assignvalues ranging from zero (totally unsuitable) to1.0 (provides all needs of the species).

To develop the most meaningful assess-ment without indexing all species in this complexavian and mammalian ecosystem, the study sitewas first stratified into vegetative communities.Then, key Great Plains Region species wereselected as indicators of each type of site.Suitability of the area for birds will be judgedusing the meadow lark or field sparrow HSImodel in areas that are primarily grassland, thedowny woodpecker or black-capped chickadeemodel for wooded regions, and a brown-thrasheror northern bobwhite quail model for shrub-dom-inated areas. Mammalian habitat assessment willuse the HSI model for the eastern cottontail ingrasslands, the fox squirrel in wooded areas, andthe bobcat in shrub-dominated sites.

Selecting HSI models most appropriate forthe geographical region and vegetative composi-tion of the ecosystem being studied will providethe most meaningful assessments. A mix of HSImodels can customize assessment to any localinterest. For example, if wetland sites wereincluded, HSI models for the mink or muskratcould be used for mammals and the bullfrog ornewt models for amphibians. Generally, a HSIvalue less than 0.8 reflects environmental condi-tions (food sources, nesting sites, brood habitat,escape cover, etc.) that will not sustain wildlifepopulations. Therefore, HSI values of 0.8 and 1.0constitute the lower and upper control values forthis study.

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Conclusions

Managing the environmental quality of anecosystem requires consideration of a spectrum ofenvironmental indicators. An evaluation programusing a customized set of indicators applied tocontrol charts can establish whether environmen-tal processes are operating within an acceptablerange. Presenting several indicators on normal-ized spider radar graphs allows for a simplified,composite visualization of environmental quality.Appropriate linking of these evaluation charts toremedial management databases can assist golfcourse superintendents, and managers of otherlands of any scale, toward establishing and main-taining a sustainable ecosystem. These studies ona newly constructed golf course are guidingresearchers in the development of an environmen-tal evaluation tool with application to a widerange of ecosystems.

References

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10. Konza Prairie Long Term Ecological Research(LTER) Program at the Konza Prairie BiologicalStation, Manhattan, KS, USA.; http//www.konza.ksu.edu

11. Larson, W. E. and F. J. Pierce. 1994. Thedynamics of soil quality as a measure of sustain-able management. p. 37-51. In J.W. Doran, D. C.Coleman, D. F. Bezdicek, and B. S. Stewart (ed.)Defining soil quality for a sustainable environ-ment. 1994. Soil Science Society of America.Special Publ. No. 35. Madison, WI.

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13. Thien, Steve J. 1998. Soil quality and sus-tainable turfgrass management. Golf CourseManagement 66(3):56-60. (TGIF Record52081)

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15. Vanoni, V. A. 1975. Sedimentation engineer-ing. p. 5. Amer. Soc. Civil Eng., New York, NY.

16. U. S. Fish and Wildlife Service. 1980. Habitatas a basis for environmental assessments. 101ESM. U. S. Fish and Wildl. Serv., Div. Ecol. Serv.,Washington, D.C.

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