Effects of plant litter diversity on soil enzyme activity and microbial community composition in a Mongolian pine plantation

AimsPlant diversity loss is increasingly recognized to affect ecological functions such as primary productivity and nutrient cycling, yet how the diversity of organic materials derived from plant litter influences soil microbial processes is largely unclear.MethodsA laboratory microcosm experiment was conducted to explore the effects of litter species diversity on soil enzyme activity and microbial community in a Mongolian pine (Pinus sylvestris var. mongolica) plantation of Northeast China in 2018. Leaf litter of Mongolian pine was decomposed with the senesced aboveground materials of three dominant understory species in all possible combinations.ResultsThe decomposition of mixed-species litter showed more cases of antagonistic effects on the activities of soil acid phosphomonoesterase, N-acetyl-beta-D-glucosaminidase and beta-glucosidase and the amount of fungal PLFAs, and synergistic effects on soil cellulase activity, the ratio of Gram-positive to Gram-negative bacteria, and the amount of actinomycetes PLFAs. Litter species composition had significant non-additive influence on soil enzyme activities and microbial community composition. According to the results of constrained redundancy analyses, litter chemical composition was significantly correlated with soil enzyme activities and microbial community composition, while the chemical diversity and stoichiometric dissimilarity had no significant effects on soil enzyme activity.ConclusionsOur results indicate that the non-additive decomposition effects of mixed-species litter on soil enzyme activities and microbial community composition depended primarily on litter species composition, which is partly explained by litter chemical composition rather than litter chemical diversity and stoichiometric dissimilarity. Our findings highlight the intricate legacy effects of species loss on soil microbial processes.