Soil Texture and Chemical Properties Influence Arbuscular Mycorrhizal Fungi Abundance, Diversity, and Richness in East African Rangelands

Abstract

Rangeland degradation in East Africa threatens soil biodiversity. Yet the diversity of native arbuscular mycorrhizal fungi (AMF) remains underexplored in this region, despite their central role in nutrient cycling, soil aggregation, and ecosystem functioning. This study assessed AMF community composition across four rangeland sites located in Kenya (Chepareria and Lokiriama) and Uganda (Matany and Rupa) as influenced by three dominant native vegetation types (bushland, grassland and wooded-grassland) and soil texture and chemical properties. AMF spores were identified to genus level, and spore abundance, taxonomic richness and diversity were quantified. Relationships between AMF metrics and soil texture and chemical properties were examined using correlation analysis. Soil properties varied significantly among sites, with higher soil C, N and clay content in Matany and Rupa compared to Chepareria and Lokiriama. Differences among vegetation types were less consistent and site-dependent. AMF abundance, richness and diversity were higher in Matany and Rupa, and lowest in Lokiriama, and were positively correlated with soil C, N, and clay content, and negatively correlated with sand content and pH. Glomus was the most dominant genus across all sites and vegetation types, reflecting its broad ecological tolerance. AMF abundance, taxonomic richness, and diversity tended to be higher in grasslands and wooded-grasslands than in bushlands, although these differences were not consistent across sites. Overall, these findings highlight the importance of soil properties in shaping AMF community composition, abundance and diversity in semiarid rangelands, with vegetation-related patterns playing a secondary and context-dependent role. Promoting soil organic matter and favorable soil conditions may therefore be key for supporting belowground biodiversity and ecosystem functioning in East African rangelands.