Effects of Red-Backed Salamanders on Ecosystem Functions

Abstract

Ecosystems provide a vast array of services for human societies, but understanding how various organisms contribute to the functions that maintain these services remains an important ecological challenge. Predators can affect ecosystem functions through a combination of top-down trophic cascades and bottom-up effects on nutrient dynamics. As the most abundant vertebrate predator in many eastern US forests, woodland salamanders (Plethodon spp.) likely affect ecosystems functions. We examined the effects of red-backed salamanders (Plethodon cinereus) on a variety of forest ecosystem functions using a combined approach of large-scale salamander removals (314-m2 plots) and small-scale enclosures (2 m2) where we explicitly manipulated salamander density (0, 0.5, 1, 2, 4 m−2). In these experiments, we measured the rates of litter and wood decomposition, potential nitrogen mineralization and nitrification rates, acorn germination, and foliar insect damage on red oak seedlings. Across both experimental venues, we found no significant effect of red-backed salamanders on any of the ecosystem functions. We also found no effect of salamanders on intraguild predator abundance (carabid beetles, centipedes, spiders). Our study adds to the already conflicting evidence on effects of red-backed salamander and other amphibians on terrestrial ecosystem functions. It appears likely that the impact of terrestrial amphibians on ecosystem functions is context dependent. Future research would benefit from explicitly examining terrestrial amphibian effects on ecosystem functions under a variety of environmental conditions and in different forest types.

Abundance, biomass production, nutrient content, and the possible role of terrestrial salamanders in Missouri Ozark forest ecosystems

“…Terrestrial salamanders also generate large amounts of biomass and are purported to exert top-down effects on invertebrate communities, litter decomposition, nutrient recycling, and carbon storage in forest ecosystems (reviewed by Davic and Welsh 2004). However, the role of specific species in ecosystem function has been difficult to elucidate, has yielded contradictory results, and continues to hinder understanding their true ecological value (Wyman 1998;Homyack et al 2010;Walton 2013;Best and Welsh 2014;Hocking and Babbitt 2014).…”

“…The first is simply that trophic dynamics are complex, they consist of direct and indirect species interactions, predator-prey relationships are spatially and temporally dynamic, top-down pressure by predators can be context dependent (e.g., litter moisture and season), and prey species often exhibit shorter generation times than predators so they can compensate for losses quickly by density release (Wyman 1998;Walton 2013;Best and Welsh 2014;Hocking and Babbitt 2014). The other difficulty is simply obtaining accurate estimates of salamander abundance needed to calculate biomass, nutrient content, and its associated variance with habitat features or different natural forest ecosystems.…”

Slow Lives in the Fast Landscape: Conservation and Management of Plethodontid Salamanders in Production Forests of the United States

“…As such, salamanders have been termed keystone species of the forest floor and lauded for their ability to regulate invertebrate prey, litter decomposition rates and even contribute to carbon sequestration [80,81]. However, examination of this body of work suggests substantial variability exists in response metrics among salamander, invertebrate and overstory tree (litter source) species [24,[82][83][84]. Whereas researchers have documented top-down regulation of some invertebrate taxa and/or leaf litter decomposition, results are inconsistent across invertebrate guilds and, in some cases, experimental designs (i.e., field plots, semi-natural mesocosms, laboratory microcosm) [80][81][82]85].…”

“…Whereas researchers have documented top-down regulation of some invertebrate taxa and/or leaf litter decomposition, results are inconsistent across invertebrate guilds and, in some cases, experimental designs (i.e., field plots, semi-natural mesocosms, laboratory microcosm) [80][81][82]85]. In other experiments, salamanders did not influence ecosystem functions or potential prey, further complicating any broader understanding of ecological roles of salamanders in the complex detrital food web [83].…”

The influence of non-salamander heterospecifics on the demography and abundance of Red-Backed Salamanders (Plethodon cinereus) in the Credit River Watershed

“…As a result of these drastic changes, a key goal in urban ecology has been to understand community interactions and determinants of community health under stressed conditions, as well as to monitor, conserve and restore natural areas to create self-sustaining ecosystems ( The RBS's terrestrial-obligate life cycle and need for moist environments, as well as their sensitivity to microclimate and air quality, results in a large range of potential habitat with variation in local environmental abiotic components that can be measured by their population abundance and demography (Ministry of Natural Resources and Forestry, 2012). RBS also play an important role in their local ecosystem through the consumption of ants, mites, earthworms, spiders and other organisms, acting as ecosystem engineers and litter decomposers (Hocking and Babbitt, 2014). This influence is projected through trophic levels, altering decomposition rates and net primary production, which are integral components in determining soil composition and ultimately dictating the composition of vegetation communities (Welsch Jr. & Droege, 2001).…”