Effects of forest cover and matrix quality on avifauna in human-modified landscapes

Abstract

Human-modified landscapes (HMLs) are a component of the Earth's surface containing remnants of natural habitat embedded in anthropogenic matrices. However, less than half of the area of ​​these matrices is composed of human settlements and intensive agriculture; the majority is comprised of low-intensity agricultural uses (e.g., silvopastoral and agroforestry systems, small-scale annual crops, extensive livestock farming, among others). Greater coverage of these lower-intensity uses implies higher matrix quality, making these areas highly potent for biodiversity conservation. In this study, I evaluated, through a review of recent literature, the effects of matrix quality and percentage forest cover on bird diversity in HMLs at the community and ecological group levels, as well as their impact on populations. I also analyzed how these characteristics in HMLs relate to ecological processes of biotic homogenization and differentiation. This review focused on the tropical region, considering studies in which the native ecosystem was forest and birds were the study group. In general terms, I conclude that two key elements that must be considered to ensure a greater contribution of HMPs to bird conservation are matrix quality (which mitigates the effects of forest loss and favors taxonomic diversity) and forest cover (which primarily favors taxonomic diversity in general and certain ecological groups). However, few studies have directly evaluated how the loss of forest cover percentage and matrix quality cause processes of homogenization and biotic differentiation in bird communities. Long-term studies are also needed to understand how occupancy, persistence, and colonization processes occur in HMP bird communities.