Forest habitats after harvesting or wildfire disturbance are usually dominated by early successional vegetation for up to 5–10 years, as well as downed wood or coarse woody debris (CWD). Abundance of Microtus voles is often highest in these sites with sufficient plant cover being crucial for population increases. The role of CWD for voles is less clear. We tested the hypotheses (H) that (H1) abundance and reproduction of meadow vole (Microtus pennsylvanicus) and long-tailed vole (Microtus longicaudus) populations would be higher on sites with greater amounts of downed wood and that (H2) this relationship would be stronger on sites with sparse vegetation cover. There were two study areas: a dry Douglas-fir (Pseudotsuga menziesii)–lodgepole pine (Pinus contorta) forest and a high-elevation Engelmann spruce (Picea engelmannii)–subalpine fir (Abies lasiocarpa) forest in southern British Columbia, Canada. We monitored the responses of meadow voles and long-tailed voles to three levels of downed wood over a 4-year period in replicated clear-cut sites at each area. Amount of downed wood did not positively influence meadow or long-tailed vole population dynamics, and hence, H1 was not supported. Variability in meadow vole numbers and vegetation precluded a test of H2 for this microtine. In dry forests, abundance of meadow voles on clear-cuts was related to the availability of cover and vertical structure provided by herbs and grasses. Vegetation cover was sparse in the high-elevation clear-cuts and long-tailed voles did seem to be positively affected by the number of pieces of CWD, but not by volume, and hence H2 appeared to be partly supported. In high-elevation or otherwise slow-growing areas, and in areas with long-tailed voles, downed wood left after harvest may provide some cover and structure.
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