Growth model used in Guzy et al. Increased growth rates of stream salamanders following forest harvesting
Guzy, Jacquelyn et al. (2022), Growth model used in Guzy et al. Increased growth rates of stream salamanders following forest harvesting, Dryad, Dataset, https://doi.org/10.5061/dryad.2fqz612q3
Timber harvesting can influence headwater streams by altering stream productivity, with cascading effects on the food web and predators within, including stream salamanders. Although studies have examined shifts in occupancy or abundance following timber harvest, few examine sublethal effects such as changes in growth and demography. To examine the effect of upland harvesting on growth of the stream-associated Ouachita dusky salamander (Desmognathus brimleyorum), we used capture-mark-recapture over three years at three headwater streams embedded in intensely managed pine forests in west-central Arkansas. The pine stands surrounding two of the streams were harvested, with retention of a 14 and 21 m-wide forested stream buffer on each side of the stream, whereas the third stream was an unharvested control. At the two treatment sites, measurements of newly-metamorphosed salamanders were on average 4.0 and 5.7 mm larger post-harvest compared to pre-harvest. We next assessed the influence of timber harvest on growth of post-metamorphic salamanders with a hierarchical von Bertalanffy growth model that included an effect of harvest on growth rate. Using measurements from 839 individual D. brimleyorum recaptured between 1 and 6 times (total captures n=1,229) we found growth rates to be 1.4 times higher post-harvest. Our study is among the first to examine responses of individual stream salamanders to timber harvesting and we discuss mechanisms that may be responsible for observed shifts in growth. Our results suggest timber harvest that includes retention of a riparian buffer (i.e., Streamside Management Zone) may have short term positive effects on juvenile stream salamander growth, potentially offsetting negative sublethal effects associated with harvest.
We assessed growth of post metamorphic D. brimleyorum with Wang’s (1998) parameterization of the Fabens method for estimating von Bertalanffy growth model parameters.
Wang, Y. 1998. An improved Fabens method for estimation of growth parameters in the von Bertalanffy model with individual asymptotes. Canadian Journal of Fisheries and Aquatic Sciences 55(2):397–400.
Included are the data and model used to estimate growth of post metamorphic D. brimleyorum.