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BackgroundFor achieving long-term sustainability of intensive agricultural practices, it is pivotal to understand belowground functional stability as belowground organisms play essential roles in soil biogeochemical cycling. It is commonly believed that resource availability is critical for controlling the soil biodiversity and belowground organism interactions that ultimately lead to the stabilization or collapse of terrestrial ecosystem functions, but evidence to support this belief is still limited. Here, we leveraged field experiments from the Chinese National Ecosystem Research Network (CERN) and two microcosm experiments mimicking high and low resource conditions to explore how resource availability mediates soil biodiversity and potential multi-trophic interactions to control functional trait stability.ResultsWe found that agricultural practice-induced higher resource availability increased potential cross-trophic interactions over 316% in fields, which in turn had a greater effect on functional trait stability, while low resource availability made the stability more dependent on the potential within trophic interactions and soil biodiversity. This large-scale pattern was confirmed by fine-scale microcosm systems, showing that microcosms with sufficient nutrient supply increase the proportion of potential cross-trophic interactions, which were positively associated with functional stability. Resource-driven belowground biodiversity and multi-trophic interactions ultimately feedback to the stability of plant biomass.ConclusionsOur results indicated the importance of potential multi-trophic interactions in supporting belowground functional trait stability, especially when nutrients are sufficient, and also suggested the ecological benefits of fertilization programs in modern agricultural intensification. Video Abstract.

The long-term (18 years) effects of re-vegetating eroded soil on soil microbial biomass, community structure and diversity were investigated in a forest soil derived from Quaternary clay in the Red Soil Ecological Experimental Station of the Chinese Academy of Sciences. Large areas of land in this region of China have been subjected to severe soil erosion, characterised by the removal of the fertile surface soil and even the exposure of parental rock in some areas due to a combination of deforestation and heavy rainfall. The effects of planting eroded or uneroded soil with Pinus massoniana, Cinnamomum camphora or Lespedeza bicolor on the soil microbial community and chemical properties were assessed. Total soil microbial community DNA was extracted and bacterial 16 S rRNA gene fragments were amplified by PCR and analysed by terminal restriction fragment length polymorphism (T-RFLP). Microbial biomass carbon (Cmic) was measured by chloroform fumigation-extraction. Following the restoration there were significant increases in both Cmic and bacterial diversity (Shannon index), and significant changes in bacterial community structure. Erosion factors were significant only in minor dimensions suggesting that the restoration had been largely successful in terms of bacterial community structure. Compared with uneroded soil, Cmic recovered in L. bicolor and P. massoniana restored eroded plots and was significantly greater under these tree species than C. camphora, although soils in C. camphora restored plots displayed the highest bacterial diversity. The recovery of microbial biomass and diversity in the eroded plots was, to large extent, accompanied by the development of the same bacterial community structure as in the uneroded plots with erosion having relatively little effect on bacterial community structure. [ABSTRACT FROM AUTHOR]

A 12 × 12 m plot from a visually uniform upland pasture was sampled in a spatially referenced manner. There was no correlation between inter-sample distance and the protozoan community (colpodid and heterotrich ciliates, flagellates, naked amoebae, and total biomass). Evidence from the other parameters measured, and from other studies reported in the literature, indicates that spatial organisation in protozoan communities occurs at scales below 10 cm. [Copyright &y& Elsevier]