Small mammal response to experimental canopy gaps in the southern Washington Cascades

  • Published source details Gitzen R.A. & West S.D. (2002) Small mammal response to experimental canopy gaps in the southern Washington Cascades. Forest Ecology and Management, 168, 187-199


This study is summarised as evidence for the following.

Action Category

Clear or open patches in forests

Action Link
Terrestrial Mammal Conservation
  1. Clear or open patches in forests

    A replicated, controlled study in 1995–1997 of three stands in a coniferous forest in Washington, USA (Gitzen & West 2002) found that creating gaps in forests did not increase abundances of most small mammal species. Species responses to treatments were not tested for statistical significance. Five to six years after gap creation, there were no clear treatment preferences among the most frequently recorded species, Trowbridge’s shrew Sorex trowbridgii (large gaps: 0.5–3.5/100 trap nights; forest: 0.0–3.8), Keen’s mouse Peromyscus keeni (large gaps: 3.1–5.4/100 trap nights; forest: 1.9–5.9) and southern red-backed vole Clethrionomys gapperi (large gaps: 0.5–1.9/100 trap nights; forest: 0.4–1.9). Seven years after gap creation, there was a similar lack of clear treatment preferences among the shrew species, montane shrew Sorex monticolus (medium gaps: 0.0–4.2/100 trap nights; large gaps: 0.3–0.6; forest: 0.6–1.2), Trowbridge’s shrew (medium gaps: 1.8–7.7/100 trap nights; large gaps: 1.2–5.7; forest: 2.1–4.8) and vagrant shrew Sorex vagrans (medium gaps: 0.0/100 trap nights; large gaps: 0.0–0.6; forest: 0.0–0.3). Gaps were created in 1990 in three Douglas-fir Pseudotsuga menziesii dominated stands, c.90, 140 and 500 years old. Gap diameters were 1 (large) and 0.6 and 0.4 (medium) times the average surrounding tree height. There were two replicates of each size/stand. Differing combinations of treatments and stands was sampled for small mammals in summer and autumn 1995–1997 using live traps, killing traps and pitfall traps.

    (Summarised by: Nick Littlewood)

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