Agricultural expansion has led to high rates of deforestation and land-use change, relegating many of the remaining native forests to networks of fragmented patches. As a result, large forest-dwelling ungulates, known to greatly impact their environment (e.g. through trampling, bioturbation of the soil, and seed dispersal), may alter movement and habitat-use patterns to accommodate for the changed spatial orientation of necessary resources. In turn, some natural patches may be subjected to an increase in ungulate impacts, while others may be devoid of ungulate influences. We created an individual-based model utilizing empirical ungulate movement data to evaluate how spatial aspects of their habitat-use intensity vary with degree of fragmentation (e.g. connectivity and number of patches) and percent of native vegetation cover. We evaluated the model using movement data from white-lipped peccaries (Tayasu pecari) in central Brazil, collected with GPS collars on animals from five herds between 2013 and 2015. In the model, a peccary herd moves across a landscape that has between 1 and 4 patches of native forest and a specified percent of forest cover (FC) between 10% and 100%. We then quantified distribution of habitat-use intensity and percent of unused native habitat after five years.
Results/Conclusions
Simulations varying only percent FC (i.e. one patch) reveal a change in the frequency distribution of habitat use from widely and evenly distributed to narrowly and heavily left-skewed as percent FC increases, reflecting a more heterogeneous use of the habitat with less FC. However, the percent of unused forest in a scenario with 10% FC as compared to 90% FC varies by less than 2%, suggesting that the majority of the patch is used in a fully connected landscape, regardless of percent FC. When the number of patches increases to 2-4, the percent of unused forest varies drastically. Below 30% FC, the percent of unused habitat in the landscape varies from 0% to 70%, as habitat use is driven by the degree of connectivity between forest patches. However, above 60% FC, the percent of unused forest is negligible (similar to one-patch simulations), indicating that patch spatial configuration is no longer the driving factor of habitat use beyond this threshold. Preliminary results for 40% to 60% FC indicate habitat use is a function of both connectivity and percent FC. Results suggest conservation measures in agricultural landscapes should emphasize percent forest cover, connectivity, or both, depending on the amount of forest remaining.