Massive structural and compositional changes over two decades in forest fragments near Kampala, Uganda

Abstract

Private forests harbor considerable biodiversity, however, they are under greater threat than reserved areas, particularly from urbanization, agriculture, and intense exploitation for timber and fuel wood. The extent to which they may act as habitats for biodiversity and how level of protection impacts trends in biodiversity and forest structure over time remain underresearched. We contribute to filling this research gap by resampling a unique data set, a detailed survey from 1990 of 22 forests fragments of different ownership status and level of protection near Kampala, Uganda. Eleven of the 22 fragments were lost over 20 years, and six of the remnants reduced in size. Forest structure and composition also showed dramatic changes, with six of the remnant fragments showing high temporal species turnover. Species richness increased in four of the remaining forests over the resample period. Forest ownership affected the fate of the forests, with higher loss in privately owned forests. Our study demonstrates that ownership affects the fate of forest fragments, with private forests having both higher rates of area loss, and of structural and compositional change within the remaining fragments. Still, the private forests contribute to the total forest area, and they harbor biodiversity including IUCN “vulnerable” and “endangered” species. This indicates the conservation value of the fragments and suggests that they should be taken into account in forest conservation and restoration.

Temporal patterns in Saturnidae (silk moth) and Sphingidae (hawk moth) assemblages in protected forests of central Uganda

“…2010; Bulafu et al. 2013), we observe large changes in moth communities. Although we do not have good estimates of the total moth richness, rarefaction curves suggest declining diversity.…”

“…Despite past encroachment, these forests have either remained relatively stable in size and structure (Zika and Mpanga; Bulafu et al. 2013) or have been recovering from disturbance (Mabira) over the resampling period (Winterbottom and Eilu 2006; Obua et al. 2010).…”

“…2013), but their surrounding matrix landscape is substantially altered; the majority of neighboring forest fragments in the greater Kampala–Entebbe landscape (Bulafu et al. 2013) and the Mpigi archipelago have either been cleared or greatly reduced in extent and/or quality.…”

Altered dynamics of broad‐leaved tree species in a Chinese subtropical montane mixed forest: the role of an anomalous extreme 2008 ice storm episode

“…2007; Bulafu et al. 2013). The Bray–Curtis dissimilarity index is bound between 0 and 1, where 1 means species composition has changed completely between time intervals, and 0 means no shift in species composition over time (Clarke et al.…”

“…2009; Bulafu et al. 2013; Luo and Chen 2013). Current environmental changes, such as drought, warming, and rising atmospheric carbon dioxide concentrations, have been identified as main drivers that could potentially modify forest structure and function such as carbon sequestration (Allen et al.…”