The influence of borassus aethiopum mart. (arecaceae) on plant diversity in Murchison Falls National Park

Abstract

Borassus aethiopum is a palm native to Murchison Falls National Park (MFNP) and over the last six decades its density has significantly increased, spreading across vast area in the northern section of the park. Despite palm savanna grasslands such as MFNP being classified as Endangered (EN) on a national level under criterion A1 of the International Union for Conservation of Nature, the ecological impact of the proliferation of B. aethiopum within MFNP remained unknown. Therefore, this study investigated the population structure of B. aethiopum, its influence on plant species diversity, and the role of soil physico-chemical properties in shaping plant distribution across four strata categorized by Borassus density: high Borassus density (HBD), moderate Borassus density (MBD), low Borassus density (LBD), and no Borassus (NB). A total of 800 plots were sampled for vegetation, and 80 for soil properties. Results revealed a curve approximating to a reverse J-shaped curve for population structure with a high density of seedlings (263.2 individuals/ha) but a sharp decline in juveniles (33.0 individuals/ha) and mature individuals (22.8 individuals/ha). Plant species richness varied significantly across strata, with NB exhibiting the highest richness (231 species, H = 4.31) and HBD the lowest (179 species, H = 3.83). However, a weak positive correlation was found between Borassus density and plant diversity (R² = 0.016, p = 0.0013), implying that B. aethiopum does not significantly suppress plant diversity. In contrast, soil physico-chemical parameters, notably pH, organic matter, sodium, sand, silt, and clay, significantly influenced species distribution (p < 0.05), as revealed by CCA and ANOVA. For example, sand had strong effects in HBD, while pH and potassium were key in MBD. Notably, B. aethiopum established across a wide range of soil types, indicating its ecological adaptability. These findings suggest that while Borassus has a weak effect on diversity, soil conditions play a more critical role in shaping plant communities. Therefore, conservation efforts should prioritize maintaining soil health alongside managing Borassus populations. The ability of B. aethiopum to persist in varied soil environments also presents opportunities for its continued establishment in the park. Based on these insights, it is recommended that park management maintain moderate Borassus density as they do not adversely affect species richness; establish permanent plots (at least 20% of sampled plots) for long-term monitoring of plant and Borassus population dynamics and investigate how Borassus populations influence mammals