Snow depth and woody debris drive variation in small‐mammal winter seed removal

Aims In temperate forests, small increases in winter temperature can lead to substantial decreases in snow accumulation, which may alter plant–consumer interactions such as seed predation. However, seed predation by small mammals may also be affected by local habitat structure (e.g., downed woody debris). We tested whether the effect of snow depth on seed predation by small mammals depends on habitat structure (woody debris) that may influence small‐mammal foraging behavior. Location Northern temperate forests in Wisconsin, USA. Methods We performed a factorial manipulation of snow depth and woody debris presence at 10 sites that differed in site‐level ambient woody debris. At these sites, we monitored seed removal of four temperate tree species (Abies balsamea, Acer rubrum, Acer saccharum, Pinus resinosa). Results Mean rates of winter seed removal varied among species, as did the effects of snow depth and woody debris. The presence of woody debris decreased Abies balsamea seed removal in plots with snow removed. Regardless of woody debris, snow removal increased Acer saccharum seed removal. Acer rubrum seed removal was lowest at sites with high site‐level woody debris volume, especially in plots with snow removed. Conclusions Warming winter temperatures may amplify seed removal for some tree species, but local‐scale heterogeneity in woody debris may modify these effects. Because the effects of woody debris and snow removal were much stronger for some tree species than others, changes in seed removal associated with reduced future snow cover or changes in forest management may accelerate regional changes in forest composition. Winter climate change is predicted to alter trophic interactions, including seed predation, but local context might modify the strength of these effects. Snow removal increased seed removal of some tree species, but effects often depended on the presence of woody debris. Predicting the effects of winter climate change on seed removal may therefore require accounting for local‐scale habitat structure.