Understanding the enhanced litter decomposition of mixed-species plantations of Eucalyptus and Acacia mangium

Abstract

Background and aims: Soil microbial-derived litter decomposition represents an important step in the global carbon and nutrient cycling and, at the local level, is primarily driven by litter chemistry. Here, we assessed how mixed-species plantations with Eucalyptus urograndis and Acacia mangium could be a key to enhancing litter production, decomposition, and soil microbial activity. Methods: The relationships between litter decomposition and litter quality and quantity were compared among 6-year-old monocultures of E. urograndis and A. mangium (E100+N and A100, respectively) and a mixed plantation of both species (E50A50). Additionally, we evaluated soil microbial biomass carbon (MBC) and nitrogen (MBN), soil basal respiration (SBR), soil enzymes and the N mineralization potential. Results: The return to soil of N via litterfall in E50A50 was greater than E100+N, while the return of P in E100+N and E50A50 were higher than A100. The decomposition rate in A100 was slower than in the E50A50 and E100+N. The microbial activity, represented by soil enzyme activities (proteases and N-acetyl-β-glucosaminidases), was consistently higher in E50A50 than in A100. Conclusion: The E50A50 presented a more balanced supply of N and P associated to a better structural quality of the litter for microbial metabolism, with synergic reflections on decomposition rates and release of nitrogen.