Effects of forest-to-agriculture conversion on soil arbuscular mycorrhizal fungi in the Western Black Sea Region

Abstract

This study investigates the effects of forest-to-farmland and forest-to-rangeland conversion on arbuscular mycorrhizal fungi (AMF) biodiversity and soil properties in Ultisols of the Western Black Sea Region, Turkey. Using a factorial design with three land-use types (forest, rangeland, and conventional tillage) and two soil depths (0-15 cm and 15-30 cm), we analysed soil samples for AMF community composition, species richness, spore abundance, and key soil hydro-physical and chemical properties. Our results revealed significant shifts in AMF biodiversity associated with land-use change (p < 0.01). A total of 35 AMF species were identified, with the highest species richness (11.32 species), Simpson index (0.91), Shannon index (2.64), and Hurlbert's PIE (0.91) observed in forest soils at 0-15 cm depth. In contrast, rangeland at 15-30 cm depth showed the highest spore abundance (491 spores 50 g(-)(1) soil), while conventional tillage at 15-30 cm had the highest Pielou index (0.86), indicating distinct ecological adaptations across land-use types. Forest soils were dominated by Racocetra coralloidea and Glomus sp., whereas rangeland soils exhibited greater frequency of Acaulospora sp. (27 %), A. scrobiculata (19 %), and Rhizophagus intraradices (14 %). In conventionally tilled soils, Glomus sp. (32 %) and Claroideoglomus etunicatum (21 %) were most prevalent, with lower overall AMF diversity, highlighting the negative impact of intensive soil disturbance. Structural Equation Modeling (SEM) demonstrated strong interdependencies between soil physical and chemical properties and AMF community dynamics. Forest conversion to rangeland and farmland led to significant reductions in AMF diversity, particularly at the surface layer (0-15 cm), where habitat simplification and soil disturbance negatively affected symbiotic interactions. Our findings emphasize the importance of sustainable land management practices, such as reduced tillage and organic amendments, to mitigate AMF biodiversity loss and preserve soil ecosystem functions. Future research should explore the resilience of AMF communities under varying land-use scenarios to guide effective conservation and agricultural strategies.