Assessing the recovery of an African medium altitude tropical rain forest after selective logging using birds as indicators

Abstract

Although birds are regarded as useful indicators of revegetated habitats, no assessment had been conducted on the regenerated compartment of Budongo forest to investigate the recovery status of the management area. This study examined forest recovery from Budongo Central Forest Reserve in Uganda. The forest has compartments at different ages of regeneration since the halting of logging operations i.e., the 35-, 55-, 71- year old, and unlogged (reference) compartment. Specifically, the study assessed bird species composition, taxonomic and functional diversity, and investigated the influence of habitat characteristics on bird taxonomic and functional diversity. Data on birds were collected in 2018 and 2019 using 20 point-counts along each of five transects per compartment. Bird feeding traits were obtained from previous bird studies on Budongo Forest Reserve. Data on habitat characteristics were collected in 2018 in 7 m radius plots at the point count sites. Data analyses were then performed in the R software. Species composition differed among the compartments with the 71-year old compartment being more similar to the primary forest compared to the younger compartments. Overall, bird species abundance, richness and evenness were higher in younger than older and primary forest compartments. Bird functional diversity did not exhibit a consistent trend along the recovery age gradient highlighting their uniqueness from taxonomic diversity. Habitat characteristics explained the abundance and functional richness of birds as well as the community-weighted means of insectivores, frugivores, insectivore-granivores, frugivore-insectivores and raptors. The results show a general trend of recovery in terms of taxonomic composition and diversity, while functional diversity is indicative of how the unique characteristics of birds of different feeding traits respond to forest regrowth. The study recommends that in order to obtain a holistic view of restoration efforts, and design appropriate biodiversity management strategies, tropical forest managers need to incorporate diverse indicators of progress in monitoring and evaluation frameworks. Such frameworks also need to include habitat characteristics as they directly influence forest biodiversity