PS 29-148 - Food-web structure in forest ecosystems: The effects of management

Abstract: Anthropogenic activities in disturbance-mediated ecosystems affect ecological processes that, in turn, can affect the stability and resilience of those ecosystems. In upland pine forests, land-use practices such as monocultural production silviculture and fire suppression have contributed to the loss of diversity-rich pine savannahs throughout the southeast. Whereas the application of management strategies has been shown to alter forest structure in pine ecosystems, less is known about how these efforts influence pathways of energy flow and the consumer-resource relationships therein. The goal of this study was to investigate the effects of forest management frequency on the trophic structure and resource use of snake communities in two pine forests under high and low management practice frequencies. We sampled snakes, prey, and dominant basal resources across each frequency treatment for three summers. Using stable isotope analysis, we compared community-wide metrics of food-web structure and performed isotopic mixing-models to determine the relative contribution of resources to snake consumers. Here we show that the high-frequency treatment supported a greater diversity of snake species, and that species exhibited increased trophic redundancy. The low-frequency treatment supported fewer snake species which were supported by a wider range of resources and occupied a wider range of relative tropic positions. Mixing-models of consumer-resource relationships, alongside prey relative abundance data, indicated that snakes were more specialized in their resource use in the high-frequency treatment, and could exploit prey of higher quality. In contrast, snakes in the low-frequency treatment were generalized in their resource use. We conclude that anthropogenic activities mimicking natural disturbances can drive food-web structure in these forest ecosystems. Frequent forest management practices (e.g., prescribed fires and thinning operations) could be implemented to support increased snake species diversity while also increasing trophic redundancy, leading to greater stability and resilience in pine-forest ecosystems. Our research further highlights the importance of ecological restoration that incorporates food-web perspectives to ensure the health of forest ecosystems.