Fungal succession, litter decomposition and root nitrogen supply in a tropical oil palm plantation

Abstract Background and Aims Industrial oil palm plantation management degrades tropical soils and disrupts ecosystem functions. Applying oil palm leaf litter can help restore soil fertility, but the underlying fungal-driven decomposition and nitrogen recycling remain understudied. This study examines fungal succession in degrading oil palm leaf litter, the fate of litter-derived nitrogen in soil and roots, and the potential for the restoration of fungal biodiversity. Methods We produced 15 N-labelled oil palms and exposed dry leaf litter in 2-mm and 37-µm mesh bags within a plantation. The finer mesh allowed microbial access but restricted roots and most detritivores. We measured litter mass loss, carbon and nitrogen dynamics, and fungal communities via ITS barcoding over six months. Root ingrowth and soil chemistry were also analyzed. Results Litter mass decreased by 70% in both mesh types, with soil accumulating litter-derived 15 N. Fine roots grew into the mesh after three months and took up 15 N , demonstrating nitrogen recycling. Fungal succession displayed clear temporal patterns: early colonizers thrived with higher C/N ratios (Hypocreales, Pleosporales, Chaetothyriales), while late colonizers (e.g., Sordariales, Pleosporales, Chaetosphaeriales ) correlated with C degradation. Arbuscular mycorrhizal fungi increased with declining C/N ratios and coincided with root growth. Conclusions Oil palm litter enhances nitrogen availability, fosters AMF diversity , and improves degraded soils. The numerous uncharacterized fungi in litter decomposition highlight the need for further research into their functional roles for sustainable soil restoration.