Print PageForest diversity and composition influence soil nutrient status in relation to microbial decomposition and carbon cycling, microbial nitrogen cycling, and microbial growth. These relationships may especially be important in the Chinese subtropics, where highly diverse forests regenerate quickly but occur on steep, erosion prone hill slopes that are often subjected to deforestation. Our research was based on the newly established Biodiversity and Ecosystem Functioning Experiment (BEF-China project) in subtropical southeastern China. The BEF-China is a large-scale Sino-German-Swiss research project consisting of experimentally planted forest plots (24 m by 24 m each, with 50 ha total area) with a total of 42 tree species and 10 shrub species planted in diversity levels ranging from 1 to 24 species. We used microbial lipid analysis, potential respiration, extra-cellular enzyme activity, and gross N-mineralization and nitrification rates to characterize the microbial community associated with a subset of 15 tree species that vary in growth rates (cm to meters per year) and other characteristics. The microbial community associated with each tree species was analyzed at different diversity levels including monocultures, 2 species mixtures, 4 species mixtures, and 8 species mixtures according to a random extinction scenario.
Results/Conclusions
Based on preliminary analysis, soil microbial biomass was roughly positively related to tree growth. Faster growing species had more soil microbial biomass, even after only two years of tree growth after plot establishment. Specifically, the general fungal biomarker was significantly positively correlated with tree crown diameter, an indicator of tree biomass. Together, these data indicate that tree species specific growth and other characteristics interact to influence fungal and general microbial growth. In addition, these species-specific effects could be more important than tree diversity in the early stages of forest regeneration.
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