Forest Management Effects on Abundance of Woodrats in Northern California

Abstract

We studied Dusky-footed Woodrat (Neotoma fuscipes) abundance and habitat associations in 39 stands of Coast Redwood (Sequoia sempervirens) forest managed for timber production during 1992, 1993, and 1999. Abundance of woodrats (Mt 1, number of unique individuals captured) in seedling/pole timber forests (<20 y) was greater than abundance in unthinned and thinned small (21- to 60-y-old) and large sawtimber (61- to 80-y-old) forests. We developed statistical models relating woodrat abundance to forest stand and forest understory covariates collected on trapping grids in thinned forests >50 y old. We used an information-theoretic approach (Akaike's Information Criterion) corrected for small sample sizes to rank models. At the forest stand level, the top-ranked model indicated woodrat abundance was negatively associated with overstory conifer stems >45.7 cm dbh. The top-ranked model relating woodrat abundance to understory habitat variables showed a negative association with log volume, Pacific Rhododendron (Rhododendron macrophyllum) and Salal (Gaultheria shallon) cover, and positive association with total understory cover. Our results from managed Coast Redwood forests of northern California indicate that woodrat abundance was greatest in young, even aged forests 5 to 20 y post-harvest. Because woodrats are a major prey species of Northern Spotted Owls (Strix occidentalis caurina) in northern California, forest management practices conducted at large scales (watershed or Northern Spotted Owl territory levels) that influence woodrat abundance have implications for the management of populations of federally threatened Northern Spotted Owls.