Avian diversity in a temperate tree-based intercropping system from inception to now

Abstract

Migratory bird populations in North America have been declining over the last several decades, largely due to habitat loss and forest cover fragmentation in both their summer breeding ranges and overwintering territories. Tree-based intercropping (TBI), which is a land-use system incorporating trees with agricultural crops on the same unit of land, is an alternative to conventional agriculture that provisions many ecological and environmental benefits in conjunction with agricultural production. This study seeks to assess the contributions of temperate TBI systems on avian biodiversity, and to quantify these changes as they develop in time. Standard bird monitoring protocols were used to examine avian communities in a TBI system at the University of Guelph’s Agroforestry Research Site in 2014 and compared to a similar study completed by Williams et al. in 1995 at the same site. The TBI system surveys were then compared to present (2014) and past (1995) avian communities living in other nearby agro-ecosystems including an abandoned field, conventional monocrop field, a willow plantation and a mature woodlot. The avian species richness and diversity at the TBI site was higher in 2014 (32 species; diversity index of 2.9) than in 1995 (17 species; diversity index of 2.2). Among land-use types, avian species richness was highest at the TBI site in both 2014 (32 species vs. 26, 24, 21, and 15) and 1995 (17 species vs. 7 and 4). The results of this study suggest that TBI systems may help to maintain and even enhance avian diversity in North America.