Carol Strojny

Date of Award

12-2004

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Wildlife Ecology and Wildlife Conservation

Advisor

Malcolm L. Hunter, Jr.

Second Committee Member

Frederick A. Servello

Third Committee Member

Robert G. Wagner

Abstract

Amphibians that inhabit upland forests are in constant contact with the forest floor, relying on moist conditions for respiration. Timber harvesting can have a negative effect on amphibian populations by altering forest floor microhabitats. We tested the hypothesis that creating small-scale canopy gaps modeled after natural disturbance patterns may retain adequate habitat structure for amphibians, thus facilitating the maintenance of amphibian diversity and abundance in managed forests. From spring -fall of 2002 and 2003, we used pitfalls with drift fences to sample 2,930 and 9,060 amphibians, respectively, in 22 large harvest gaps, 22 small harvest gaps, 19 natural canopy gaps, and 36 closed-canopy forest plots located in the Penobscot Experimental Forest of central Maine. Location within large harvest gaps (north vs. south aspect, gap center vs. edge) did not influence capture rates for Ambystoma maculatum, Notophthalmus viridescens, Plethodon cinereus, Rana catesbeiana, or Rana sylvatica, but higher capture rates at gap edges than gap centers were detected for Rana clamitans. Responses among gap types (large harvest, small harvest, and natural) varied by amphibian species and age-class. Metamorphs (young of the year) had relatively lower capture rates in large harvest gaps for A. maculatum, R. catesbeiana, R. clamitans, and R. sylvatica. In some cases (R. clamitans juveniles, R. sylvatica juvenile-adults and metamorphs), capture rates in small harvest gaps were similar to natural gaps. We did not detect statistically significant (p < 0. I ) differences among gap types for N. viridescens, Rana palustris, juvenile-adult A. maculatum or P. cinereus, although for juvenile-adult A. maculatum, we caught relatively fewer individuals in all gap types than in closed-canopy areas. We also explored relationships between the size of down woody material and its use by P. cinereus, a terrestrial salamander, in harvest-created gaps and closed-canopy forest. Log searches (N = 231) for P. cinereus indicated that the probability of detecting a salamander is least for small logs in harvest-created gaps, whereas in closed-canopy forest, the probability was both higher and constant among log sizes. These results suggest that harvest gaps, especially small gaps, provided habitat analogous to natural gaps for some amphibian species.

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