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UBC Theses and Dissertations

Habitat predictors of a vertebrate community in a fragmented neotropical landscape Seetharaman, Keerthikrutha

Abstract

Habitat is an area that allows a species to survive and thrive. Habitat loss and habitat modification are considered two major threats to species persistence. Habitat predictors are environmental conditions which dictate patterns in species occupancy and thereby community distribution. Understanding habitat predictors at multiple spatial scales can aid managers in directing conservation measures, predicting effects of habitat modification and advancing theoretical knowledge about the effects of habitat fragmentation. Habitat predictors of ground-dwelling Neotropical vertebrates at multiple spatial scales, especially landscape scales, are often poorly known. To fill this knowledge gap, I conducted a study in a fragmented forest landscape in Guanacaste Province, Costa Rica. In the 1960s, continuous tropical wet forests in my study area were burnt to clear land for cattle ranching. This process modified swathes of wet forests into smaller fragments surrounded by human-use areas. I chose 19 forests in this landscape situated in and around the Área de Conservacíon Guanacaste (ACG), a UNESCO World Heritage Site, documented vertebrates using camera traps and calculated habitat variables at the three spatial scales of camera trap point, forest and landscape using field measurements and remote sensing imagery. We documented 32 species of ground-dwelling vertebrates and calculated 13 aspects of the vertebrate community as response variables. We tested the ability of 12 habitat variables to explain variation in the community response variables using linear mixed effect modelling in an AIC-based model averaging framework. Our results show that different scales of habitat affect different aspects of the vertebrate community, highlighting a need for examination of multi-scale habitat variables. Habitat predictors at landscape scales were important to the widest range of vertebrate response variables. Our key results highlight that threatened species associated with areas of continuous forests and species richness were highest in forests surrounded by plantation matrix as opposed to pasture. Detections of species at higher trophic levels (e.g. large carnivores) increased with the amount of forested area within 2km of camera traps. Our study thus highlights the need to examine various aspects of a vertebrate community, not just species richness, in order to understand in-depth, the effects of habitat change.

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