PARENT SESSION
Oral Session 14: Reptiles and Amphibians I: Salamanders and Newts.
Presiding: K McCoy
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room D 136.
Effects of riparian reserves and forest harvesting on body condition of juvenile and adult northwestern salamanders (Ambystoma gracile).
Hilton, Alana*,1, Richardson, John1, 1 University of British Columbia, Vancouver, B.C., Canada
ABSTRACT- Amphibians may be particularly sensitive to microclimate changes associated with forest harvesting due to their physiological requirements for moist conditions. Several studies have shown declines in amphibian species richness and population size in harvested areas, although studies in the Pacific Northwest have had mixed results. Maintaining riparian reserves may mitigate the impacts of forest harvesting for amphibians. We examined variation in size-weight relations for juvenile and adult northwestern salamanders in sites that had clearcuts, riparian reserves and second-growth forest. We hypothesized that salamander weights corrected for size (condition factor) would be lower in clearcut sites than forest sites, with condition in buffer sites intermediate. Salamanders were trapped during the fall of seven consecutive years (1997-2003) in 2 replicates of each of the 3 treatments, and weight and snout-vent length measurements were recorded. Data for juveniles and adults were analyzed separately to avoid legacies of the larval habitat rather than the terrestrial habitat. We used a mixed model analysis of covariance (weight ln-transformed, size as covariate) to determine the effects of treatment, year, and site within treatments. There was no significant effect of treatments, site or year on juveniles. A split-plot analysis for adults showed no significant effect of year or treatment; however, the site within treatment interaction with the covariate was significant (p<0.003). One of the clearcut sites had a significantly lower slope of the weight-size relation than the other 5 sites. These results suggest that site differences were more important than treatment effects in affecting the allometry of northwestern salamanders at these sites.
Key words: forest harvesting, body condition, Ambystoma gracile, riparian reserves