School of Forest Resources

(Strojny and Hunter) – From spring-fall of 2002 and 2003, pitfalls with drift fences were used over 250,000 trap nights 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. 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. A statistically significant (p < 0.1) difference among gap types was found for N. viridescens, Rana palustris, juvenile-adult A. maculatum or P. cinereus, although for juvenile-adult A. maculatum, relatively fewer individuals were caught in all gap types than in closed-canopy areas. Of the 12 species sampled, only juvenile and adult spotted salamanders (Ambystoma maculatum Shaw) showed a consistent, negative population response to harvest gaps.

The relation between the size of down woody material and its use by northern red-backed salamanders (Plethodon cinereus Green) in harvest- created gaps and closed-canopy forest was explored. Log searches (N = 231) for red-backed salamanders indicated that the probability of detecting a salamander was least for small logs in harvest-created gaps. Active searches of moderately-decayed class II-III logs under a closed forest canopy indicated that presence of red-backed salamanders varied by log size, ranging nearly linearly from about 6% for 10 cm logs to over 50% for 45 cm logs, 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.