Woody Species Alpha-diversity and Species Abundance Distributions in an African Semi-deciduous Tropical Rain Forest
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Date
2015
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Publisher
Biotropica
Abstract
Understanding plant species diversity patterns and distributions is critical for conserving and sustainably managing tropical rain forests of
high conservation value. We analyzed the alpha-diversity, species abundance distributions, and relative ecological importance of woody species
in the Budongo Forest, a remnant forest of the Albertine Rift in Uganda. In 32 0.5-ha plots, we recorded 269 species in 171 genera and
51 families with stems of ≥2.0 cm in diameter at breast height (dbh). There were 53 more species with stems of ≥2.0 cm dbh than with
stems of ≥10 cm dbh, of which 33 were treelets and 20 were multi-stemmed shrubs. For both minimum stem diameter cut-offs (i.e., ≥2 cm
dbh vs. ≥10 cm dbh), the Fabaceae, Euphorbiaceae, Ulmaceae, and Meliaceae families and the species Cynometra alexandri, Lasiodiscus mildbraedii,
and Celtis mildbraedii had the highest relative ecological importance. The relative ecological importance of some species and families
changed greatly with the minimum stem diameter measured. Alpha-diversity, species richness, and species abundance distributions varied
across historical management practice types, forest community types, and as a function of minimum stem diameter. Species richness and
Shannon–Weiner diversity index were greater for species with stems of ≥2.0 cm dbh than of ≥10 cm dbh. The decrease in species evenness
with an increasing number of plots was accompanied by an increase in species richness for trees of both minimum diameters. This forest is
characterized by a small number of abundant species and a relatively large proportion of infrequent species, many of which are sparsely distributed
and with restricted habitats. We recommend lowering the minimum stem diameter measured for woody species diversity studies in
tropical forests from 10 cm dbh to 2 cm dbh to include a larger proportion of the species pool.
Description
Keywords
Albertine Rift Eco-region, Alpha-diversity, Familial importance value, Minimum stem diameter, Rarefaction diversity
Citation
Mwavu, E. N., & Witkowski, E. T. (2015). Woody Species Alpha‐diversity and Species Abundance Distributions in an African Semi‐deciduous Tropical Rain Forest. Biotropica, 47(4), 424-434. Doi: 10.1111/btp.12223