Effects of biomass harvest on eastern red-backed salamanders

Patrick J Ruhl, Purdue University

Abstract

In a typical forest harvest, the volume of coarse woody debris (CWD) increases from nonmerchantable material (i.e., tree-tops, limbs, and small-diameter trees) left on the forest floor. Biomass harvesting removes much of this material for bioenergy production. When removed, ecosystem services associated with CWD, such as seedbed substrate, nutrient cycling, and essential wildlife habitat, is reduced. Woodland salamanders have strict microhabitat and soil moisture requirements that make them especially sensitive to timber harvest practices, particularly those that remove CWD, a primary habitat for the group. I monitored the abundance of Eastern red-backed salamanders ( Plethodon cinereus) in response to a gradient of retained CWD following timber and biomass harvesting, a first study assessing the impacts of wood-based biomass harvest on plethodontids. I considered key aspects of salamander physiological health such as standard metabolic rate (SMR) and body condition. Calculating SMR of P. cinereus in different harvest regimes has been used as a proxy of forest ecosystem health. In this study I also field-tested the assumptions of current SMR extrapolation techniques. N-mixture abundance models indicated a positive correlation between the percent of retained CWD and P. cinereus abundance. Standard metabolic rate of encountered salamanders was not affected by the CWD retention gradient in any sampling season. However, SMR variance was significantly larger in harvested stands in Fall 2013. Within this sampling season, salamander mass was more variable in harvested stands, and snout vent length was significantly lower in harvested stands. This discrepancy in salamander size between harvested and unharvested stands in Fall 2013 has implications for the current SMR calclulation technique, which utilizes the temperature profiles of different harvest treatments and extrapolates SMR for P. cinereus based on a standardized one-gram salamander. Although a threshold of resilience for plethodontids based on a gradient of retained CWD was not discernable, this study emphasizes the need for future wildlife research on biomass harvesting in order to ensure appropriate implementation of regulations that provide better protection of the integrity and biodiversity of forest ecosystems.

Degree

M.S.

Advisors

Dunning, Purdue University.

Subject Area

Wildlife Conservation|Zoology|Forestry

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