The influence of forest characteristics on avian species richness and functional diversity in Southern Mistbelt Forests of South Africa

Changes to natural environments as a consequence of human population growth are a major threat to biodiversity. Natural habitat modifications, changes in vegetation structure and habitat characteristics have resulted in decreased species richness and functional diversity in wildlife populations. Species' distributions, abundance and persistence are generally reliant on habitat suitability, landscape configuration and ability to disperse and colonise habitats. We aimed to determine the influence of vegetation structure, patch size and isolation distance on avian communities in Southern Mistbelt Forests in the provinces of KwaZulu-Natal and Eastern Cape, South Africa, across a variety of forest patches during the breeding and non-breeding seasons. We conducted fixed-radius point-count surveys to determine avian species richness and functional diversity, and quantified the vegetation foliage profile in 54 distinct forest patches across three study areas. Multivariate analyses showed significant differences in vegetation structure among forest patches and subsequent variation in avian species richness and functional diversity across the study areas during the non-breeding season. Avian beta diversity was significantly driven by the reduction in forest patch size and habitat structural complexity. Reduction in forest size and complexity reduced avian species richness and functional diversity. Increasing isolation distance negatively influenced avian diversity. We recommend further improving the regulatory standards concerning sustainable utilisation of forest resources that subsequently change forest characteristics to promote a healthy and diverse habitat structure and safeguard avian communities.