Relative importance of timber harvest and habitat for reptiles in experimental forestry plots

Abstract

Forestry practices affect various habitat characteristics that influence wildlife populations. Understanding the relative importance of the broad effects of forestry practices versus specific habitat variables for wildlife may help managers balance multiple forest management objectives and potentially adjust forestry practices to better conserve biodiversity. We compared the relative importance of experimental timber harvest treatments (clearcutting, thinning to remove undesirable tree species) to habitat variables (coarse down wood, herbaceous vegetation, leaf litter) for captures of reptiles in central Missouri, USA for two years post-harvest. We also used drift fences along the edges between uncut control forest and clearcut to detect changes in movements between treatments after timber harvest, which is one potential mechanism for differences in captures among timber harvest treatments. We found that habitat variables best predicted captures of small snakes, while both habitat and timber harvest treatment predicted lizard captures. Two lizard taxa (Plestiodon spp., Sceloporus undulatus) had higher captures in clearcuts than in the no harvest control, which is consistent with studies across the southeastern United States. Plestiodon spp. showed significantly more movements into clearcuts from control forest than in the opposite direction, demonstrating that higher captures in clearcuts were at least in part due to immigration from adjacent forested areas. Small snakes and Sceloporus undulatus captures were higher in areas with more coarse down wood and higher herbaceous vegetation cover, which were associated with the clearcut plots. These results for small snakes are consistent with another study in Missouri, but in contrast to two from South Carolina, indicating that there may be regional differences in the response of small snakes to forestry practices. Further work on the effects of forestry management on reptiles should examine regional differences and seek to understand underlying mechanisms.