Most Recent Update: 15 September 2008 - RMS
Purpose and Need
All forest and woodland animals need dense cover throughout the year for various reasons, including: (1) concealment, (2) protection from predators, (3) protection from severe weather, and (4) for resting or loafing cover. In areas where dense tangles of brush and vines are absent or limited, artificial brush or slash piles can be constructed in conjunction with timber operations to provide much needed cover for ground-dwelling and nesting game and non-game birds, small mammals, reptiles and amphibians, other small animals, and their arthropod prey.
In well managed multiple-use forests, periodic timber harvests generate coarse woody debris. Depending upon the species of wood, brush and slash usually decays back into the soil within 5 to 10 years. Additionally, if firewood is harvested from a forest, less residual coarse woody debris (CWD)is left. In either case, but especially in situations with little CWD, piles provide sufficient structure to provide many of the benefits of CWD in forest stands.
In the absence of disturbance, forest stands (particularly old-growth forests) accumulate considerable CWD. Woody debris helps to protect tree seedlings, and provides cover for a host of invertebrate and vertebrate animals. Some species of trees actually find more favorable seedbeds on rotted logs or stumps than on the forest floor, particularly in late successional forests and in moist riparian hardwood corridors. Scattered brush and slash rots away in a few years, soon losing its favorable structural benefits to the forest. Additionally, brush and slash piles last much longer than scattered slash. Additionally, they create richer sites for regenerating trees, and serve as a potential surrogate to CWD for the benefit of animal diversity, that can be more effectively managed, placed, and monitored.
Increased species diversity resulting from piling of brush and slash is not restricted to animals. Tree seedlings that require rich humus or that otherwise would be consumed by various herbivores (mice, rabbits, squirrels, deer, elk) can often survive in old piles or along edges of younger piles where they are protected from predation, wind, and excessive loss of moisture. Additionally, some species like the canes of blackberries and raspberries (Rubus spp.) and vines of wild grapes (Vitis sp.) often grow larger and produce heavier crops of fruit around margins of old piles. Dark, loamy soil left when a pile completely decays remains for years afterwards continuing to nurture berries, other shrubs, and trees that eventually replace them. Piles can be even more effective when placed on gullies or in areas where erosion or disturbance has disrupted the soil.
Small mammals (rodents, rabbits, shrews, moles) that burrow into old piles undoubtedly provided additional fertilizer for plants that grow there. California Quail have been observed to fly into hardwood brush piles that were being constructed, and as many as 48 individual birds (five species of sparrows, Spotted Towhee, California Quail) have been observed using a brush pile within 15 minutes of completing the pile in eastern Shasta County (R. M. Sullivan pers. comm.).
Habitat retention areas (HRAs), usually <1 acre usually associated with clear-cut blocks in forest harvesting areas, have occasionally been assumed to provide similar functional wildlife habitat value as piles. However, HRAs are not a substitute for well constructed piles. For example, unlike HRAs, piles provide additional, often very different, and important structural and functional wildlife habitat elements required by virtually all small ground-dwelling animals, including:
- Protection from predation and weather provided by the actual physical density, texture, and thickness of the pile construction
- Insulation quality conferred directly to the occupant of the pile
- Significant insulation during the critical over-wintering period, particularly in dry and more importantly wet snow and rain
- Valuable escape and concealment cover
- Denning, hibernating, nesting, perching, and resting sites/chambers (small mammals, birds, amphibians, reptiles, pond turtles) that are actually part of the constructed pile itself
These elements represent quality habitat elements not always selected for, found, or quantified within individual HRAs. Ideally, a combination of HRAs and associated piles that are strategically placed within the clear-cut unit would represent a much more optimal combination of functional wildlife habitat elements within the forested unit. Further, these piles are easily planned for, quantified, placed, monitored, and management for compared to comprehensive surveys of down woody debris.
Increase quality and quantity of wildlife habitat on managed timberlands
Educate the public as to the value of brush and slash piles as important wildlife habitat
- Provided the science, logic, and guidelines demonstrating the benefits to wildlife of pile construction on harvestable forest units
- Provide guidelines that are easy to use, economical, and effective in construction of piles
- Provide options and alternatives that do not constrain timber operations
- Provide additional habitat structure to complement other wildlife management practices
- Provide a potential surrogate (alternative) for large woody debris that can be easily managed
- Comply with California Forest Practice Rules that hazard reducing by identifying the: (1) percent and (2) constraints associated with enumerating and locating piles within the harvestable forest unit
Location and Quantity
Brush and slash piles should be constructed within forests, along forest edges (ecotones), and in openings, field corners, or along margins of streams and marshes. Piles should be situated near grassy areas or cultivated lands so that food, water, and nesting habitat can easily be found near the protective cover of the piles. In open areas where cover is lacking, 3 to 4 piles per acre should be constructed. Generally, 2 to 10 piles per 2.5 acres (1 hector) are enough for smaller, less mobile wildlife such as quail, other ground dwelling birds, rodents, and rabbits (Giles 1978). Usually, piles are 100 to 200 feet (30 - 60 m) a part (U.S. Army Corps of engineers 1977, Martin and Steel 1984); however along woodland borders or even clear cut units/polygons adjacent to uncut forest, 1 pile every 200 to 300 feet (61 - 91 m) will provide adequate cover as well as travel lanes to other areas.
Within forested timberlands where harvesting takes place slash piles for the creation of wildlife habitat can be placed within: (1) individual select cut units (individual selection), (2) areas scheduled to be thinned, (3) group selection treatments, (4) areas scheduled for rehabilitation, (5) various shelter wood systems, (6) areas that involve various restoration efforts (meadows, riparian/hardwood release), and (7) along edges of clear cut-units between forest and treatment polygons.
General Construction and Placement
Quality wildlife habitat in its basic form requires the close proximity of cover, water, and food. As such, brush and slash piles should be built in conjunction with various types of brush, woodland, or forest clearing or thinning activities. If placed within areas devoid of concealment cover or shelter, they provide stepping stones or travel corridors to connect other suitable habitats for quail and other ground-dwelling game and none game species; including piles placed between clear-cut areas and watercourse and lake protection zones (WLPZs), or riparian/hardwood corridors associated with various stream classifications. Such woody material, especially when built with a log base provides excellent habitat for aquatic and amphibious wildlife (pond turtles, salamanders, toads) that depend on riparian areas for much if their life history (Anderson et al. 1978 and Swanson et al. 1976). Piles should not be placed in the middle of an eroding gully, where they might be washed away, or along well-used roadsides (Allen 1969). Road-side placement of piles is a danger to quail and other small animals and should be avoided. Piles used as roosts for quail are recommended within 50 feet (15 m) of brush cover and within 0.62 miles (1 km) of water (Kosciuk and Peloquin 1986).
Materials used for the piles depend upon what is locally available. Rot resistant trees, such as various species of oaks and locust, make durable bases for piles as do old lumber or timbers. The base of the pile should be formed by placing alternate layers of logs (culls and unmerchantable conifers or hardwoods) at right angles to one another. Logs are considered to be more important as wildlife habitat than are other forms of woody debris because they persist longer in the environment (Brown 1970, Wagener and Offord 1972). Logs used should be at least 6 inches (15 cm) in diameter and spaced 6 to 10 inches (15 - 25.4 cm) apart in each layer.
To increase durability of the pile, logs and other base layers may be stacked on top of stones, large boulders, tires, root wads, old railroad ties, or even cinder blocks. The stump of a large tree, cut off about 2 to 2 ½ feet (60 - 76 cm) above the ground can also serve as a base. Importantly, these base layers (especially logs) will act to keep pathways open under the pile once the brush or slash is placed on top. A pile of sticks and branches that are not elevated is not a brush-or slash-pile. Also, for highly managed wildlife habitat, placement of a piece of black heavy-duty plastic spread out and placed horizontally within the upper two-thirds of the pile provides very effective insulation and a barrier to rain and melting snow during the over-wintering period and actually extends the life of the pile (R.M. Sullivan, pers. obs.).
Although the difference in ambient temperature between open ground and leaf-litter and the interior of a brush or slash pile may not be insignificant under the same ambient condition (except direct sun light), when a brush or slash pile is actually occupied by an animal the isolative properties of a well constructed pile far outweighs an open area of random leaf litter, particularly in slushy or deep snow. Smaller trees, brush, and slash should be piled on top of the base loges until a mound or tepee-shaped pile is created. Any brush or slash may be used as filling on the piles; hardwood tree tops will last longer, but evergreens (discarded unmerchantable smaller trees, saplings, or discarded Christmas trees) can provide excellent, short term cover. Finished piles should be 6 to 8 feet (1.8 - 2.4 m) tall and from 15 to 20 feet (4.6 - 6.1 m) in diameter. If a rectangular shaped pile is constructed, it should be a least 15 to 20 feet (4.6 - 6.1 m) wide and at least 25 to 30 feet (6.1 - 9.1 m) long.
It is important to build piles dense enough in the center to provide adequate shelter from adverse weather (winter show and wind) and predators but loose enough around the edges to allow for easy access. Strict attention should be given to size of the piles built. The tendency is to make piles too small. If a person can kick a pile over, or a dog can burrow through them, they are too small. In our area of northern California, some of the best piles for wildlife are created by building: (1) on a patch of dense living brush so that the live plant can continue to grow within the pile or (2) create a pile where native vegetation (grasses, upland and riparian shrubs/hardwoods, vines) are allowed to grow-up into and around the pile. Both situations are examples of “living brush/slash piles” and “half-cuts,”  the objective of which is to provide cover on or near the ground without killing the plant.
Species of trees/brush best suited for construction of living piles include: various species of willow (Salix spp.), western juniper (Juniperus occidentalis - excellent), curlleaf mountain mahogany (Cercocarpus ledifolius), manzanita (Arctostaphylos spp), live oak (Quercus spp.), lemonade berry (Rhus integrifolia), buckbrush (Ceanothus spp.), toyon (Heteromeles arbutifolia), aspen (Populus tremuloides), maple (Acer spp.), and chokecherry (Prunus virginiana). Although not practical for timber harvest operations, piles should be inspected periodically and refurbished with new limbs and branches as old material rots and limbs become dislodged (Martin and Steel 1986). Living brush piles generally last from 3 to 5 years depending on geographic location (Steel and Martin 1986, Webb and Guthery 1982).
For ease of construction, slash piles may also be constructed by placing a triangle or rectangle of small logs gathered by a feller-bundler, such that each side and the middle of the triangle/rectangle is composed of a bundle. The center of the slash pile is then filled with limbs and tips of the trees extending out from the bundles to act as support, internal structure, and insulation. Using this method the slash pile can be constructed very quickly during the time the equipment is at the site, thus reducing the amount of physical labor and potential injury from lifting individual logs by hand.
Monitoring of slash piles was conducted consecutively over a two (2) day period (27 - 28 Aug 2008), which included approximately 4 hrs in the morning (07:00 -11:00) and 4 hours in the afternoon (13:00 -17:00 hrs) over both days. All 12 piles were visible by use of binoculars from a low-lying and concealed location positioned within the center of the 17 acre meadow.Numbers of pile types included two standard piles (Fig. 1), four constructed piles (Fig. 5), and six feller-buncher piles (Figs. 7 and 8). The centrally located observation point allowed all piles to be observed simultaneously by visual scanning every 3 to 5 minutes and recording use by wildlife. Additionally, each pile was photographed and its perimeter and interior was observed by walking around each pile to identify any white-wash, kill/plucking sites, animal tracks, or burrowing and beading activities into or adjacent to the pile. Placement of piles and fire safety issues follow recommendations presented elsewhere in this document. Monitoring of piles will be conducted at least six times per year to assess seasonal variation in use by wildlife, and condition and longevity of various types of pile structures and configurations.
Species Use of Slash Piles – Figures 9, 10, and 11 show preliminary results of monitoring, extent of use of different piles by wildlife, and overall species composition during the month of August, 2008. Feller-buncher piles were used most frequently (57.1%) by different taxa, followed by constructed piles (33.8%), and standard piles (9.1%). Of 145 individuals representing 17 different species of birds and mammals, the most common species using piles were bluebirds (17.9%), kinglets (12.4%), and nuthatches (11.0%). Of these, bluebirds used standard piles 15.4%, constructed slash piles 30.8%, and feller-buncher piles 53.8% of the time (Fig. 9). Kinglets used standard piles 5.6%, constructed piles 38.9%, and feller-buncher piles 55.6% of the time; whereas, nuthatches used standard piles 6.3%, constructed piles 50.0%, and feller-buncher piles 43.8% of the time. Frequency of use by different species of various types of piles is provided in Fig. 8. Mourning Doves (n = 4) used standard piles exclusively (100% of the time); whereas Douglas squirrels (n =1) and black-tailed deer (n = 1 bedding sites) used feller-buncher piles exclusively. This pattern, however, is likely a function of small initial sample sizes. Compared to adjacent clear-cuts, there was much greater activity by wildlife species in the grassy dry meadow. However, incorporation of slash piles into a adjacent clear-cut with subsequent comparative monitoring of various types of piles of similar composition would provide further insight into use of piles as functional wildlife habitat in both meadow and adjacent clear-cut habitats.
Green Live Vegetation Within Meadow – Birds were found in close association with green/live and dead vegetation, which was specifically left within the dry grassy meadowas part of the meadow enhancement activities. These plant species included willow, lodge pole pine, grease wood brush, and mountain mahogany. Birds used this vegetation for cover, resting and perching platforms, and to hawk back-and-forth into grassland habitat, which contained various grasses, weedy plant species such mullet, and other shrubs and forbs, and which provided seeds/buds as well as insect foods.
Large Green Wildlife Trees Within Meadow – Several large (= 24 inches dbh) green wildlife conifer trees were also left within the dry grassy meadow. These were heavily used by bird species similar to other smaller green live vegetation discussed above. However, these trees received many more visits from Red-breasted Nut Hatches and other woodpeckers (Northern Flicker, Harry Woodpecker), and Steller’s Jays, compared to live shrubs and other plants. From these green wildlife trees woodpeckers and jays feed on insects and darted back-and-forth into adjacent forest habitat surrounding the meadow. Additionally, several green lodge pole pine trees (approximately 12-16 inches dbh) within the interior of the dry grassy meadow were girdled to provide future snag habitat (Fig. 12). These girdled trees were similarly used by birds, particularly when trees were associated with nearby adjacent green vegetation.
Meadow-Forest Ecotone – There was much wildlife activity along the ecotone (edge) of the dry grassy meadow and forest interior. Most ground squirrel activity occurred here in association with large boulders and large woody debris (logs and stumps), which were found in greater abundance along the edge of the meadow relative to meadow interior.
Except for Mountain Bluebirds, most birds could be found within the ecotone at some time during the morning or late afternoon; thus supporting the ecological hypothesis that ecotonal areas between two very different habitats (meadow and forest) generally attract a comparatively large number of species (biologically diverse), likely due to juxtaposition and increased plant/habitat diversity of ecological conditions found there (microhabitat, foods, cover, shelter, etc.).
Snags Within Meadow – There was one large snag (< 30 inch dbh) left within the dry grassy meadow, which was essentially centered within the 17 acres and functioned throughout the day as a perch for Mountain Bluebirds to access much of the meadow grassland habitat (Fig. 13). They frequently used this perch after hovering while foraging for insects above open grassland, as apposed to hawking or perch-foraging on insects in association with accumulations of live shrubs (primarily willow) at other feeding sites within the meadow.
Burrows and Bedding Sites Within Slash Piles – One well developed burrow system (Fig. 14, likely a ground squirrel, southern exposure) and one deer bedding site were found in association two large feeler-buncher piles (northern exposure) (Fig. 15).
Raptorial Bird Species – No significant evidence of white-wash or kill/plucking sites were observed on or in association with piles, which would indicate that piles were not currently being used by raptorial species of species that might be foraging in association with the dry meadow and forest edge habitats.
Timber Harvest Plan Guidelines and Suggested Measures
The following recommendations are designed to: (1) identify what the California Forest Practice Rules (CFPRs) require regarding construction and treatment of brush or slash piles and (2) provide guidelines for construction of piles within the context of the CFPRs for use by wildlife as part of a normal Timber Harvest Plan (THP). As such, the CFPRs (Article 7 - Hazard Reduction [page 76] Sections 937) provide standards for: (1) treatment of logging slash in order to reduce fire and pest safety hazards in logging areas, (2) protection of such areas from potential insect and disease attack, and (3) preparation of the area for natural or artificial reforestation while retaining wildlife habitat (937.2). Additionally, placement of slash or brush piles that conform to these guidelines are clearly much less a hazard to potenital fire within a loged forested ecosystem than are brush piles placed along major paved roadways, which may or may not be burned on an annual basis (Fig. 14).Within the context of Article 7, the following recommended guidelines for creating wildlife habitat by use of brush or slash piles include leaving approximately ten percent (10%)  of all piles within the boundary of the THP should be left unburned to provide additional functional wildlife habitat for the reasons discussed above. This prescription may be applied when piles within harvest units will be managed by:
- Individual selection of trees
- Individual selection of trees
- Group selection
- Shelter wood systems
- Various restoration efforts (meadows, riparian/hardwood release).
- Piles that contain large wood debris (>16 inches [40.6 cm] in diameter by 16 feet [4.9] in length) or where they abut the base of snags may also be retained to provide wildlife habitat.
- Piles should usually not exceed 20 x 20 x 10 feet (6.1 x 6.1 x 3.1 m).
- Piles should be placed at least 5 feet (1.5 m) away from the high-water line on Class I, Class II, and Class III streams to prevent accumulations of material that could obstruct natural stream flow during peak, seasonal, or periodic ephemeral flows.
- Piles located on a 100 year floodplain or upland terrace should be retained.
- Piles that meet any of the following three (3) criteria, however, may be burned:
- Piles with dimensions > 20 x 20 x 10 feet (6.1 x 6.1 x 3.1 m) or of an equivalent volume.
- Piles within 100 feet (30.5 m) of a public road or within 50 feet (15.2 m) of a permanent private road open for public use where permission to pass is not required.
- Piles that show evidence of being suitable breeding material for populations of an insect pest.
- The remaining ninety percent (90%) of the piles within the boundary of THP may be treated in accordance with the following CFDRs standards:
- Treatment of Slash to Reduce Fire Hazard (917.2, 937.2, 957.2)
- Prescribed Broadcast Burning of Slash (937.3)
- Burning of Piles and Concentrations of Slash (917.5, 937.5, 957.5)
- Notification of Burning (917.6, 937.6, 957.6)
- Protection of Residual Trees (17.7, 937.7, 957.7)
- Prevention Practices (917.9, 937.9, 957.9)
Allen, D.H. 1969. The farmer and wildlife. Wildlife Management Institute, Washington. 62pp.
Anderson et al. 1978. The role of aquatic invertebrates in processing or wood debris in coniferous forest streams. American Midland Naturalist 100(1):64-82.
Brown, J.K. 1970. Physical fuel properties of ponderosa pine forest floors and cheat grass. U.S. Forest Service Resource Paper INT-74. Intermountain Forest and Range Experiment Station, Ogden, UT. 16pp.
Dimock, E.J. 1974. Animal populations and damage. In Environmental effects of forest residues management in the Pacific Norwest: A state-of-knowledge compendium. U.S. Forest Service General Technical Report. PNW-24, p 01 to 0-28. Pacific Northwest Forest and Range Experiment Station, Portland Oregon.
Giles, R.H. 1978. Wildlife Management. W.H. Freeman, San Francisco. 416pp.
Garrison, G.A. and J.G. Smith 1974. Habitat of grazing animals. In Environmental effects of forest residues management in the Pacific Northwest: A state-of-knowledge compendium. U.S. Forest Service General Technical Report PNW-24, p. P-1 to P-10 Pacific Northwest Forest and Range Experimental Station, Portland, Oregon.
Gutierrez, R.J. et al. 1984. Managing small woodlots for wildlife. Information Bulletin 157, College of Agriculture and Life Science, Cornell University, Ithaca NY. 330.
Kosciuk, J.R. and E.P. Peloquin. 1986. Elevated quail roosts. Sec 5.1.5., U.S. Army Corps of Engineers wildlife resources management manual. U.S. Army Eng. Waterways Exp. Station Technical Report EL-86-18. 15pp.
Lay, D.W. 1965. Quail management handbook for east Texas. Texas Parks and Wildlife Department Bulletin 34. 46pp.
Leopold, A.S. 1977. The California quail. University of California Press, Berkeley. 281pp.
Martin, C.O. and J.L. Steel. 1984. Brush structures for wildlife. Wildlife Resource Notes, U.S. Army Corps of engineers Information Exchange Bulletin2(2):1-2.
Pierovich, J.M. 1975. Forest residues management guidelines for the Pacific Northwest. U.S. Forest Service general Technical report PNW-33. Pacific Northwest Forest and Range Experiment Station, Portland Oregon. 281pp.
Steel, J.L, and C.O. Martin. 1986. Half-cuts. Sec 5.3.2, U.S. Army Corps of Engineers wildlife resources management manual. U.S. Army Engineers Waterways Experimental Station Technical report. EL-86-14.8pp.
Swanson et al. 1976 History, physical effects, and management implications of large organic debris in western Oregon streams. USDA Forest Service General Technical Report PNW-56. Pacific Northwest Forest and Range experiment Station, Portland Oregon. 15pp.
Thomas, J.W. 1979. Wildlife habitats in managed forests the Blue Mountains of Oregon and Washington. Agriculture Handbook No. 553, USDA Forest Service. 512pp.
U.S. Army Corps of Engineers 1977. General wildlife management measures. U.S. Army Engineers District, Fort Worth, TX. 38pp.
Wagener, J.W. and H.R. Offord. 1972. Logging slash: Its breakdown and decay at two forests in northern California. USDA Forest Service Research Paper PSW-83. Pacific Southwest Forest and Range Experiment Station, Berkeley, California. 11pp.
Webb, W.M. and F.S. Guthery. 1982. Responses of bobwhite to habitat management for northern bobwhites in northwest Texas. Journal of Wildlife Management 47:220-222.
 Half cuts are constructed by cutting partway through trunks of saplings or small deciduous trees (Leopold 1977, Steel and Martin 1986, Lay 1965, Gutierrez et al. 1984). To increase the value of half-cuts, trees that harbor such fruit-producing vines as California wild grape (Vitis californica), blackberry (Rubus spp.), and poison oak (Toxicodendron diversilobum) can be selected and cuts made in the spring after sap has risen and leaves have matured.
 Retention of 10% of the brush or slash piles throughout the area is also consistent with the general practice of retaining down and dead woody debris for wildlife cover within the harvested area (Dimock 1974, Garrison and Smith 1974, Pierovich 1975, Thomas 1979).