Species richness, composition, and dominance of core and climate relicts of African miombo woodlands

Abstract The miombo woodlands, which span about 10% of the African continent, are essential for the ecosystem services they provide. These woodlands are mainly dominated by the genera Julbernardia , Isoberlinia , and Brachystegia . However, there is limited understanding of how species dominance and richness change in relict sites, which are far removed from the core miombo woodlands. In this study, we anticipated that relict sites would show reduced species diversity due to their isolation from the core miombo woodlands and their exposure to different species compositions. We sampled vegetation using modified Whittaker plots (50 m × 20 m) across four sites: core miombo woodland ( n = 14), miombo edge ( n = 19), Mozambique relict ( n = 18), and South Africa relict ( n = 21). Within each plot, we measured tree height, basal diameter, and canopy dimensions for mature trees; root collar diameter for saplings (20 m × 5 m subplots); and recorded seedling species and counts (in 5 m × 2 m subplots). Temperature and rainfall gradients were also assessed across the sites. Species richness, Shannon–Wiener diversity, and species evenness were compared between sites using one‐way analysis of variance (ANOVA). Species composition differences between sites were evaluated using analysis of similarity (ANOSIM). Our results revealed a pattern where species richness, the Shannon–Wiener index, and evenness increased with decreasing relict size. Interestingly, evenness declined from juvenile to adult stages within sites, suggesting changes in species composition over time. Significant differences in species composition were observed between sites, with the most pronounced dissimilarities between the core miombo woodland and Mozambique relict. Our findings highlight that while key miombo species remained dominant and important, the relict sites demonstrated increased species richness. This suggests that these isolated sites might harbor high biodiversity, potentially due to their high perimeter‐to‐area ratio, which makes them more susceptible to species invasions. Additionally, the warmer temperatures recorded at the relict sites could be driving thermophilization, further contributing to the richness and diversity observed. These insights are crucial for informing conservation strategies for miombo woodlands and their relicts in the face of ongoing climate change.