Soil mesofauna drives litter decomposition under combined nitrogen and phosphorus additions in a Brazilian woodland savanna

Abstract

AbstractNutrient enrichment and the subsequent chemical changes in dystrophic savanna soils may alter plant richness and nutrient use efficiency, thereby affecting leaf litter chemistry and decomposition. However, the role of soil mesofauna in litter decomposition in savanna ecosystems under nutrient enrichment is not well understood. In soils from a long‐term fertilisation experiment, we evaluated the decay of leaf litter incubated in fine‐ and coarse‐mesh bags over a year to assess the role of soil mesofauna in litter decomposition in the central Brazilian savannas. Experimental plots were established in a woodland savanna and consisted of nitrogen (N), phosphorus (P), N plus P and lime additions and untreated control (three replicates of each). We evaluated the effect of fertilisation and liming on litter decomposition rates (total, mesofauna‐mediated and microbe‐mediated) and their relationship with the initial litter quality (N, C, lignin, cellulose and polyphenol content). Litter decomposition rates were significantly higher in coarse‐mesh bags in the N plus P treatment compared with the control, which was explained by mesofauna‐mediated decomposition but not by the initial litter quality. Litter mass losses in fine‐mesh bags were significantly higher in the initial months of the experiment in the N treatment and in the intermediate months in the N plus P treatment compared with the control. This result could be explained by the initial litter N content, although it has not reflected in significantly higher microbe‐mediated decomposition rates. The litter mass losses in coarse‐mesh bags in the N plus P treatment were significantly higher only in the final months, indicating that microorganisms and mesofauna differentially affect decomposition over time. Our findings suggest that combined N and P addition could alter soil organic matter dynamics in Brazilian savannas by increasing soil mesofauna‐mediated litter decomposition rates.