School of Biological and life Science

The Indian Ocean Coastal Belt Forest is extremely biodiverse but is threatened by anthropogenic land-use change. In South Africa, remnant forest patches are divided into highly restricted but protected indigenous forest (IF) and abundant but unprotected coastal thicket/dense bush (DB), which likely represents secondary/regenerating IF. We tested the hypothesis that DB had value for conserving forest-dependent avian taxonomic and functional diversity, as (a) DB is situated with in the forest-anthropogenic land-use mosaic and (b) birds maintain diverse ecosystem functions and are sensitive to environmental change given their varied biological traits. We conducted 149 and 112 fixed-radius point-count surveys of avian communities in 99, and 24, patches of DB and IF, respectively, at each location recording microhabitat vegetation structure. We compared vegetation characteristics and taxonomic species richness between vegetation classes, and tested the breadth of functional trait-space and for significant associations with vegetation structures at each survey location, using RLQ analysis. Vegetation classes differed significantly, but floral species overlap and vegetation structures in DB closely resembled regenerating IF habitat. Specialist ground-nesting and insect-gleaning species corresponded to taller, more diverse IF structures. Other biological traits and total species richness overlapped broadly across both classes, but IF had significantly higher mean species richness. Given the relatively high taxonomic and functional diversity of the avian community in the abundant DB, the scarcity of IF, and the proximity of DB to the anthropogenic land-use mosaic, we recommend allocating suitable DB patches to the Protected Area Network, which may simultaneously help preserve avian taxonomic and functional diversity , facilitate colonisation throughout the fragmented landscape and provide ecosystem services to anthropogenic land uses.

The Indian Ocean Coastal Belt (IOCB) of South Africa is a natural forest-grassland mosaic, nested within an anthropogenic, mixed land-use matrix. Given the ongoing threat of agricultural expansion and urbanisation, we assessed the value a buffer habitat (dense bush) for conserving forest species. We investigated the influence of microhabitat complexity on mammal communities within and dense bush habitats, using occupancy modelling. We found vertical stratification gradients as observed in studies of tropical forest chronosequence, i.e. increased foliage density in lower habitat layers and decreased foliage density in higher habitat layers for dense bush, and vice versa for forest. Structural composition suggests that dense bush is within a successional stage of secondary forest regeneration. Bushbuck (Tragelaphus scriptus) occupancy was higher in forest than dense bush, while the opposite was true for blue duiker (Philantomba monticola). Large-spotted genet (Genetta tigrina), Cape porcupine (Hystrix africaeaustralis) and marsh mongoose (Atilax paludinosus) occupancy remained constant between habitats. Grey duiker (Sylvicapra grimmia) occupancy varied greatly between dense bush (0.48 ± 0.01) and forest (0.16 ± 0.01). Dense bush appeared to maintain natural forest assemblages, and may play a crucial role in buffering IOBC forest patches, given their highly-restricted distribution. However, dense bush habitats have no protection status, but play a role in the conservation of forest plants and animals. Therefore, we advocate the inclusion of dense bush habitats in conservation networks focused on forests.

The spotted ground thrush (Zoothera guttata; SGT) is a globally endangered forest specialist whose distribution is poorly understood in the critically endangered Indian Ocean Coastal Belt Forest (IOCBF) biome on the east coast of southern Africa. More than 70% of the IOCBF has been lost to development, resulting in fragmented forest remnants within a mosaic of different land uses. We conducted camera-trap surveys with 5796 trap-days in 82 forest patches of various sizes across a gradient of land-use types in the IOCBF during the winter seasons of 2014–2016 to establish occupancy (W) of SGT. We used occupancy modelling and incorporated forest microhabitat characteristics and surrounding land-use classifications to compare sites and determine SGT distribution across the habitat mosaic. The top model estimated an average W = 0.39 ± 0.09, and detection probability (P) = 0.11 ± 0.03. At the landscape scale, larger, less isolated patches had a higher W of SGT while P decreased with proximity to cultivated land. At the micro-habitat scale, a high percentage of bare ground influenced W positively but P negatively, as did short grass cover. However, short herbaceous cover and high stem density of large (11–15 m) trees influenced P positively. These results detail the influence of landscape-scale factors including forest fragmentation and conversion to agriculture in conjunction with forest microhabitat-scale characteristics, on patch selection and distribution of a cryptic, ground-dwelling species that is both threatened and under-studied. Given its endangered status and dependence on larger and more mature forest patches, SGT may be an effective flagship species for the conservation of threatened IOCBF patches

Aim: We investigated habitat heterogeneity and patterns of avian taxonomic and functional diversity change across a decreasing patch-size gradient in a critically endangered, fragmented forest-system to elucidate: (1) habitat patch-size and structural drivers of avian diversity change, (2) potential patch-size thresholds at which avian diversity and habitat heterogeneity changes occurred and (3) avian species/ communities within thresholds that indicated distinct patch-size categories. Location: Indian Ocean Coastal Belt, South Africa. Methods: We conduced habitat-structure and fixed-radius point-count surveys during the avian breeding season across 123 habitat patches (range 0.06–386.9 ha). We calculated taxonomic and functional diversity/patch (a) using a distance matrix of all traits present in the avian community (c) and described community change across the patch-size gradient (b). We compared linear regressions of patch-size