Mechanical Treatments

• Why use mechanical treatments?

• What factors effect use of mechanical treatments?

• What types of mechanical treatments are there?

• How effective are mechanical treatments?

Mechanical Treatments

• Why Use Mechanical Treatments?– Alter dense, closed canopies

• Woody plants (trees & shrubs*)• Succulents

• Herbaceous plants

Credit: laspilitas.com

Mechanical Treatments

• Why Use Mechanical Treatments?– Alter woody plants*

• Overstory & understory/shrub– Competes for

» Sunlight» Water » Nutrients

– Limit productivity of herbaceous– Unsuitable for many wildlife species

» Edge» Early successional

Credit: ecotours.com

Mechanical Treatments

• Why Use Mechanical Treatments?– Enhance herbaceous plant growth

• Set back succession• Disrupt compacted soils• Remove debris• Manipulate soil micro-topography

Mechanical Treatments

• Why Use Mechanical Treatments?– Alter soil & litter conditions– Site & seed-bed preparation

NOT a substitute for prescribed fire

- Combination often best

Mechanical Treatments

• Factors to Consider– Wildlife factors

• Obligate wildlife species– Interior species

• Ecological requirements of species– Edge species & species with multiple habitat needs

• Native plants: pros & cons• Forage (open area) to cover ratios• Proximity of treated sites to other habitats• Influence on vertical structure• Control of spot grazing (livestock attraction)

Mechanical Treatments

• Factors to Consider– Watershed/soil factors

• Soil fertility• Soil depth• Debris & litter• Erosion• Aspect• Slope• Topography• Season of treatment

Mechanical Treatments

• Factors to Consider– Vegetative factors

• Reseeding & plant propagation• Invasion by “weeds” & exotics• Target plants: pros & cons • Sprouting potential (return interval)• Maintenance of openings• Impact on plant diversity• Season of treatment

Credit: californaichaparral.com

Mechanical Treatments

• Overstory Removal– Areas cleared of trees & tree manipulations

• Harvest (silviculture)• Timber Stand Improvement

Mechanical Treatments

• Overstory/Tree Removal– Harvest

• Chainsaw• Harvester (mechanical shears or saw)

Mechanical Treatments

• Timber Stand Improvements

(TSI; Tending/Intermediate Treatments)– Thinning– Pruning

– Vertical & horizontal structure

Mechanical Treatments

• Understory and Shrub Removal– Areas cleared of woody species

• Mosaic patches• Cleared strips• Large areas

Mechanical Treatments

• Level of Understory/Shrub Removal

(Payne and Bryant 1994)

Mechanical Treatments

• Thinning– Individual tree or shrub treatment

• Chainsaw or handsaw• Heavy equipment

• Grubbing– Below ground severing

• Clipping– Above ground severing

Vegetation/land sculpting

Mechanical Treatments

• Thinning– Mechanical grubbing

• U-shaped blade mounted on a tractor– Depending on tree/shrub type and terrain

» Crawler (rough terrain; poor movements; high soil disturbance)

» Wheel loader» Farm tractor

Mechanical Treatments

• Thinning– Mechanical grubbing

Crawler Wheel-loader Farm tractor

Credit: reveg-catalog.tamu.edu

Mechanical Treatments

• Thinning– Mechanical grubbing

• Excavator– Considerable site disturbance– Wide swath– 200-500 trees/hr

Credit: reveg-catalog.tamu.edu

Mechanical Treatments

• Thinning– Mechanical clipping

• Hydraulic shears– Spray stump for sprouters (e.g., mesquite, redberry juniper)

Credit: libertyhilltractor.comCredit: onlineattachements.com

Mechanical Treatments

• Clearing– Areas cleared of all woody species

• Remove aboveground growth• Sever roots• Uproot plants from soil

• Usually a combination of methods

Mechanical Treatments

• Clearing– Chaining (or cabling, railing, etc.)

• Ship anchor chain• Pulled between two tractors• 61-122 m (200-400 ft) in length• 59-111 kg/m (40-75 lbs/ft)• U-shape

Mechanical Treatments

• Clearing– Chaining

Credit: fs.fed.us

Mechanical Treatments

• Clearing– Chaining

• Uproots plants & severs• Used for tree felling

– Dense to moderate stands– High soil moisture best– Not limber plants

• Double-chaining (both directions) & Elevated chaining

• Effects short-lived & used with other methods– Herbicide before and/or burn after

• Common in West– Pinyon pine, juniper, mesquite

Credit: reveg-catalog.tamu.edu

Mechanical Treatments

• Clearing– Rootplow

• V-shaped, horizontal blade• 3-5 m (10-16 ft) wide• Large crawler tractor• Depth 31-36 cm (12-14 in)

Mechanical Treatments

• Clearing– Rootplow

• Severs roots & crowns– Best for trees <4” dia.

• Prevents regrowth– Often followed by chaining or raking

• Severe soil disturbance– May need to reseed

• Long-term results– 85-99% tree mortality– 10-20 yrs before shrubs return

Credit: reveg-catalog.tamu.edu

Mechanical Treatments

• Clearing– Web plow

• V-shaped, horizontal blade• Large grader• Depth 10-15 cm (4-6 in)

Mechanical Treatments

• Clearing– Web plow

• Severs roots & crowns• Prevents regrowth

• Worked well on saw palmetto

Mechanical Treatments

• Clearing– Disking

• Blades 61-91 cm (24-36 in)• Units 2.5-3.7 m (8-12 ft) width• Crawler or tractor

Credit: reveg-catalog.tamu.edu

Mechanical Treatments

• Clearing– Disking

• Severs roots & crowns shallow species– Not “heavy” shrubs/brush and trees

• Problem severing deep rooted species• Disturbs soil

– Stimulates early successional growth

• Effects on shrubs short-lived• May increase deep-rooted species

May benefit wiregrass

Mechanical Treatments

• Clearing– Roller-chopping

• Cylindrical metal drum– Adjustable weight

• Blades parallel to axis• Crawler or tractor

Credit: reveg-catalog.tamu.edu

Mechanical Treatments

• Clearing– Roller-chopping

• Severs stems• Crushes plants• One or more drums• Water or cement filled

• Disturb soil• Increase herbaceous plants• Required every 2-5 years with strong resprouters

• Often used in conjunction with fire

Credit: forestryimages.org

Mechanical Treatments

• Clearing– Renovators/Aerators (roller chopper)

• Small blades• Staggered, cylindrical pattern• Double drums• 46-107 cm (18-42 in) diameter• Filled with water

Credit: reveg-catalog.tamu.edu

Mechanical Treatments

• Clearing– Renovators/Aerators

• Moderate to dense shrubs– Can remove top growth to stimulate regrowth

• Small blades – Chop debris– Form basins in soil

Credit: noble.org

Mechanical Treatments

• Clearing– Shredder

• Brush– Rotating horizontal blade, vertical shaft

• Flail– Rotating vertical blade, horizontal shaft 2-6 m (7-20 ft) wide

Mechanical Treatments

• Clearing– Shredder (brush hog & rotobeater)

• Cut woody plants and debris (<12”)• Manicured appearance and level height• Prone to mechanical failures• Effective on sm. trees and non-sprouters• Often in conjunction with fire

Credit: reveg-catalog.tamu.eduCredit: reveg-catalog.tamu.edu

Mechanical Treatments

• Clearing– Mower

• Flail• Rotary• Sickle-bar

• Tractor

• Remove top-growth• Herbaceous and very light woody plants• Very temporary effects• Often used in conjunction with fire

Credit: allswisstractors.com

Credit: tractorbynet.com

Mechanical Treatments

• Clearing– Blading or dozing

– Often used with other methods– Much disturbance

Mechanical Treatments

• Re-sprouting (lots of browse!)– Disking– Roller-chopping– Shredding– Mowing

• Roots • Crowns• Stems

Credit: images.google.com

Mechanical Treatments

• Other – Raking– Bailing

Mechanical Treatments

• Planting and tending– Seeders

• Drills & spreaders

– Planters

– Disturbance

USDA photo by: Tim McCabe 

Mechanical Treatments

• Planting and tending– Cultipackers & rollers– Hoes, disks, plows, etc.

– Disturbance– Soil compaction

Mechanical Treatments

• Other Plant Harvesting

Mechanical Treatments

• Mechanical Treatments– Why they are used– Types– Factors affecting their use and effectiveness