Influence Of Plant Litter Quality And Diversity On Soil Arthropod Community And Contribution Of Soil Arthropod To Nitrogen Mineralization In Humid Tropical Forests, Southwestern China

Forest litter is direct or indirect source of food and energy to soil fauna. We initiated this study to examine the influence of litter quality and diversity on the soil fauna community and soil nitrogen mineralization driven by soil arthropod in tropical matureforest of Xishuangbanna, SW China. We employed split plot design. The principal factor include litter diversity (4,10,19 species) and quality (high C/N and low C/N). The second factor is soil arthropod (with soil arthropod, and soil arthropod exclusion). Soil and litter were sampled after treatment two and five months. We compared soil inorganic nitrogen, soil nitrogen mineralization rate, soil microbial biomass carbon and soil arthropod and microbe community structure between treatments. The results are as follows:1) Forest litter quality did not change soil arthropod community structure or diversity significantly, but did influence population number and distribution of some soil arthropod groups. For example, when mixed litter was 19 species, the individual density of Acarina was higher in high litter quality treatment than that in low litter quality. Meanwhile, the diversity of mixed litter can did significant effect on soil arthropod community and diversity. When the litter quality was low (high C/N), the more species of litter mixture, the higher diversity was of soil arthropod community. 2) There was significant influence of soil arthropod on the soil mineral nitrogen content. Soil arthropod exclusion resulted in significant reduction for the nitrogen content, but enhanced the nitrogen mineralization rate.3) There was significant effect of litter diversity on the fauna effect on total mineral nitrogen content instead of litter quality. The soil fauna can significant enchance the mineral nitrogen in 10 and 19 litter species condition, but not in 4 species. In other words, the soil arthropod contribution to nitrogen mineralization process occurred in both high and low quality litter condition, where leaf litter C/N ratio was ranged from 40 to 20%.4) Changes of litter quality or diversity had not significant effect on soil microbial community structure or soil microbial biomass carbon in the short experment time.In summary, our results indicate that, in Xishuangbanna tropical forest, soil arthropod plays a critical role in the nitrogen mineralization process-as a whole. Meanwhile, the plant litter diversity may influence soil arthropod community and its contribution to nitrogen mineralization. We also suggest that the conservation of plant diversity in tropical forests is necessary to maintain high species and functional group diversity of soil fauna. Moreover, the conservation of soil faunal diversity and functional groups ensures that important ecosystem processes such as decomposition and biogeochemical cycling are maintained.