Category: Ecological Research
Title: Habitat Associations of the Sagebrush Lizard (Sceloporus graciosus): Potential Responses of an Ectotherm to Ponderosa Pine Forest Restoration Treatments
Author: * Knox, S.C. , Chambers, C.L. , Germaine, S.S.
Subject: Wildlife, Ponderosa pine (Pinus ponderosa), Ecological Restoration
Abstract: Little is known about the response of ectotherms to ponderosa pine (Pinus ponderosa) restoration treatments. The ambient body temperature of an ectotherm affects its physiology, development, and behavior. Microhabitat availability and heterogeneity are critical factors in determining which thermoregulation choices are available to a terrestrial ectotherm (Stevenson 1985). Forest restoration treatments (for example, thinning and burning) will alter herpetofauna microhabitats by decreasing tree canopy cover and allowing more sunlight penetration to the forest floor. This change could, depending on the species, have positive or negative effects on the populations of the area. We sampled microhabitat use by Sceloporus graciosus (sagebrush lizards) in northern Arizona at Grand Canyon-Parashant National Monument using standard pitfall-array sampling methodology. Univariate analyses were used to relate lizard abundance to ponderosa pine tree density, percent soil cover, percent rock cover, litter depth, and insect density. In a multivariate analysis, ponderosa pine density (negatively correlated) and bare soil cover (positively correlated) were the best predictors of lizard abundance. Restoration treatments will increase small-scale heterogeneity within S. graciosus territories by increasing accessibility into and out of sunlight. Based on the thermoregulatory demands of this species, these changes should benefit S. graciosus. However, other possible indirect effects of restoration treatments such as increases in predation on lizards (due to greater visibility), as well as changes in food availability, could negatively impact lizard populations. Future research should focus on pre- and postrestoration treatment monitoring of herpetofauna, and on the direct effects of fire on herpetofauna populations within restoration sites.
Source: Rocky Mountain Research Station Proceedings
Publisher: USDA Forest Service, Rocky Mountain Research Station, http://www.fs.fed.us/rmrs/