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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 Credit: reveg-catalog.tamu.edu Crawler Wheel-loader Farm tractor 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: onlineattachements.com Credit: libertyhilltractor.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 Credit: reveg-catalog.tamu.edu • 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 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 Credit: forestryimages.org • Disturb soil • Increase herbaceous plants • Required every 2-5 years with strong resprouters • Often used in conjunction with fire 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.edu Credit: reveg-catalog.tamu.edu Mechanical Treatments • Clearing – Mower • Flail • Rotary • Sickle-bar Credit: allswisstractors.com • Tractor • • • • Remove top-growth Herbaceous and very light woody plants Very temporary effects Often used in conjunction with fire 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