AN INTERDISCIPLINARY APPROACH TO EVALUATING THE IMPACT OF AGRICULTURAL INTENSIFICATION ON BATS IN A DYNAMIC NEOTROPICAL LANDSCAPE
Thesis (Ph.D., Natural Resources) -- University of Idaho, 2016 | Almost 40% of the planet’s ice-free surface has been converted to agriculture . In this context, successful biodiversity conservation depends on maximizing the potential of dynamic agricultural landscapes to support native species, while allowing for sustainable agricultural production. This dissertation uses an interdisciplinary approach to evaluate impacts of agricultural intensification on the balance between conservation and production in the agricultural landscape of the San Juan – La Selva biological corridor in Costa Rica. In the first chapter, we describe and quantify how agricultural intensification in the form of pineapple plantations is driving changes in social, economic, and spatial characteristics of the landscape. Results indicate that pineapple expansion is simplifying and homogenizing both the local economy and the agricultural matrix between remnant forest cover. This creates a less diversified, more vulnerable economy and a landscape with lower potential for biodiversity conservation. The second chapter evaluates impacts of pineapple expansion on bat assemblages, and finds that this process is altering assemblage composition in remnant forest patches, resulting in higher proportions of frugivorous bats and lower proportions of insectivorous bats than in old-growth forests. We identify a potential threshold effect whereby patches surrounded by more than 50% forest can retain assemblage composition similar to that found in old-growth forest. In the third chapter, we use a landscape genetics approach to quantify the effect of pineapple expansion on functional connectivity for two widespread and abundant bat species, Artibeus jamaicensis and Carollia castanea. To support these analyses, in the fourth chapter we develop fourteen novel microsatellite markers for C. castanea. Results suggest that functional connectivity for A. jamaicensis remains high, but historical habitat loss and fragmentation and recent pineapple expansion have begun to disrupt gene flow for C. castanea. This work provides evidence for the importance of maintaining spatially and economically diverse land uses in complex agricultural landscapes, and fills important gaps in current understanding of how bat populations are responding to the trend of agricultural intensification in the tropics.