Action: Gather coarse woody debris into piles after felling
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- Two studies evaluated the effects on mammals of gathering coarse woody debris into piles after felling. Both studies were in Canada.
COMMUNITY RESPONSE (1 STUDY)
- Richness/diversity (1 study): A randomized, replicated, controlled study in Canada found higher mammal species richness where coarse woody debris was gathered into piles.
POPULATION RESPONSE (2 STUDIES)
- Abundance (2 studies): One of two randomized, replicated, controlled studies in Canada found higher counts of San Bernardino long-tailed voles where coarse woody debris was gathered into piles. The other study found higher small mammal abundance at one of three plots where debris was gathered into piles.
BEHAVIOUR (0 STUDIES)
Coarse woody debris consists of fallen dead trees and cut branches that are left during tree harvesting. Gathering coarse woody debris into piles, either at a single point or as a line of debris across the forest floor, can increase structural diversity on a forest scale relative to evenly spreading the material.
Supporting evidence from individual studies
A randomized, replicated, controlled study in 2006–2009, of a lodgepole pine Pinus contorta-dominated forest in British Colombia, Canada (Sullivan & Sullivan 2012) found that gathering coarse woody debris from tree harvest waste into piles resulted in higher counts of San Bernardino long-tailed voles Microtus longicaudus than where debris was uniformly dispersed. There were more voles in plots where woody debris was gathered into piles at single points (9 voles/ha) or piles comprising rows of debris (7 voles/ha) than in plots where it was dispersed evenly (1 vole/ha). Within plots where woody debris was gathered in piles, more were caught within the piles (11–16 voles/ha) than on open ground (3 voles/ha). Plots were largely clearfelled in October 2006. Course woody debris was gathered into piles or uniformly dispersed. There were three replicate plots of each treatment, 0.2–3.0 km apart. Voles were sampled over two nights, at 4-week intervals, in May–October of 2007, 2008, and 2009, using Longworth live traps in a grid of 49 points across 1 ha in each plot.
A randomized, replicated, controlled study in 2005–2010 of three forest sites in British Colombia, Canada (Sullivan et al. 2012) found that plots with piles of coarse woody debris had greater small mammal abundance than did plots where woody debris was evenly spread at one of the three sites and that species richness was higher with debris in piles across all sites or in one of three sites, depending on survey method used. More small mammals were trapped in plots with course woody debris in single piles (38/plot) or arranged in lines (37/plot) than with evenly dispersed woody debris (21/plot) at one site. There were no differences at the two other sites (piles: 18–27; dispersed: 14–23/plot). Species richness of trapped mammals followed a similar pattern at the site with an abundance difference, with more species in plots with woody debris piles (4.3–4.6/plot) than with dispersed woody debris (3.7/plot). There was no difference at the other two sites (piles: 3.3–3.9; dispersed: 3.1–3.6). However, snow-tracking surveys recorded more mammal species in plots with course woody debris piles (2.7–3.4/plot) than with dispersed woody debris (1.7/plot). Trees (dominated by lodgepole pine Pinus contorta) were harvested at three sites in 2005–2007. Each site had three randomly assigned replicates of course woody debris gathered into single piles (2–3 piles/ha, 1–3 m high), debris gathered into rows (1–3 m high) and evenly dispersed debris. Plots within a site averaged 0.6–0.8 km apart. Small mammals were live-trapped for three nights and two days, at 4–8-week intervals, in May–October of 2007–2009. Mammal tracks were surveyed, generally three days after snowfall, twice each winter, from 2007–2008 to 2009–2010.
- Sullivan T.P. & Sullivan D.S. (2012) Woody debris, voles, and trees: Influence of habitat structures (piles and windrows) on long-tailed vole populations and feeding damage. Forest Ecology and Management, 263, 189-198
- Sullivan T.P., Sullivan D.S., Lindgren P.M.F. & Ransome D.B. (2012) If we build habitat, will they come? Woody debris structures and conservation of forest mammals. Journal of Mammalogy, 93, 1456-1468