Category: Ecological Research
Title: Landscape-Scale Forest Habitat Relationships to Tassel-Eared Squirrel Populations: Implications for Ponderosa Pine Forest Restoration
Author: Dodd, N.L. , Schweinsburg, R.E. , Boe, S.
Subject: Ecological Restoration, Habitat, Ponderosa pine (Pinus ponderosa), Wildlife
Abstract: Pinus ponderosa (ponderosa pine) forest ecosystem restoration is a growing emphasis in the southwestern United States to address over 120 years of forest structure change, decreased forest health, and increased potential for disease and wildfire. Restoration treatments replicating presettlement conditions may reduce tree density by 98(percent), are detrimental to canopy-dependent wildlife such as tasseleared squirrel (Sciurus aberti), particularly at the patch scale, and are of concern when applied at the landscape scale. We examined S. aberti population dynamics in north-central Arizona, U.S.A., from 1999 to 2002 at nine 280-ha sites oriented along a landscape gradient of varying proportions (4.699.2(percent)) of unlogged, high-quality (HQ) habitats within a matrix of intensively thinned low-quality habitat. Our objectives were to estimate S. aberti density, juvenile recruitment, and survival across this gradient; quantify patch- and landscape-scale habitat relationships to populations; evaluate possible habitat thresholds in squirrel population response; and develop forest management recommendations. In regression models, both patch-scale and landscape-scale parameters influenced squirrel populations. At the patch scale, number of interlocking canopy trees was added most frequently, whereas the proportion of HQ habitat was the landscape-scale variable added in five of seven models. Recruitment and survival at dense, HQ plots were inversely related to number of small, saplingsized trees. Nonlinear thresholds in density and recruitment occurred when the proportion of HQ habitat at study sites was between 24 and 42(percent). Our study points to the importance of maintaining HQ habitat in mesoreserves on the landscape at or above this threshold range, as well as pursing a mix of forest management prescriptions in the matrix surrounding mesoreserves to achieve wildlife, forest restoration, and fire risk reduction objectives.
Source: Restoration Ecology
Publisher: Society for Ecological Restoration International, http://www.ser.org