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Background: For 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., Results: We 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., Conclusions: Our 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., (© 2023. The Author(s).)

Soil is increasingly under environmental pressures that alter its capacity to fulfil essential ecosystem services. To maintain these crucial soil functions, it is important to know how soil microorganisms respond to disturbance or environmental change. Here, we summarize the recent progress in understanding the resistance and resilience (stability) of soil microbial communities and discuss the underlying mechanisms of soil biological stability together with the factors affecting it. Biological stability is not solely owing to the structure or diversity of the microbial community but is linked to a range of other vegetation and soil properties including aggregation and substrate quality. We suggest that resistance and resilience are governed by soil physico-chemical structure through its effect on microbial community composition and physiology, but that there is no general response to disturbance because stability is particular to the disturbance and soil history. Soil stability results from a combination of biotic and abiotic soil characteristics and so could provide a quantitative measure of soil health that can be translated into practice. [ABSTRACT FROM AUTHOR]

Re-vegetation of trace element contaminated soils can alter the pH and chelating capacity in the rhizosphere, increasing the mobility of pollutants, which, in turn, may impact on rhizosphere ecology. In this study a short-term pot experiment was carried out in order to investigate the multi-factorial effects of: buffering capacity (sandy-loam and loam soils); pollutant load (0%, 1.3%, and 4% of pyrite sludge), and the presence/absence of plant (Lolium perenne L. and Medicago sativa L.) on the mobility of trace elements, soil biochemical functionality (hydrolase activities), and biological diversity (bacterial and nematode communities). The experiment was carried out with representative soils from the Guadiamar basin (SW Spain), an area where the Aznalcóllar mining spill affected over 4000ha. Results indicated that the development of rhizospheres in polluted soils (coarse-textured) increases the mobilization of trace elements. In general the presence of roots has stimulatory effects on soil quality indicators such as hydrolase activities and both bacterial and nematode communities. However, the presence of high amount of metals interferes with these beneficial effects. This study provided evidence about the complexity of the impact of growing plants on trace element polluted soils. Trace element mobilization, hydrolase activities and bacterial and nematode communities in the rhizosphere are dependent on plant species, soil type, and pollution dose. [Copyright &y& Elsevier]

Four similar, agricultural soils with distinct nematode communities were used to determine the extent to which soil and inoculum factors affected nematode community structure. The soils all had a sandy loam texture from the same geographical area and had been in pasture or arable rotation for the last 10 years. Treatments were established in pots containing a middle layer of frozen defaunated soil, sandwiched between an inoculum that was either fresh soil from the same site ('self') or a mixture of soils to give a more diverse inoculum ('mixed'). Principal component analysis indicated that a single soil type given different inocula developed different community structures (i.e., the community under 'self' differed from that under 'mixed') suggesting an inoculum effect. It was also true that different soil types under a single inoculum soil also developed different community structures (i.e., community under 'mixed' differed with soil type), suggesting a soil effect. It is likely that the nematode community structure is influenced by a combination of antecedent land use, soil factors, species introductions and inter-species competition, which should be considered in any interpretation of nematode communities as a biotic indicator. [ABSTRACT FROM AUTHOR]

In terrestrial ecosystems decomposing cadavers act as resource patches affecting nutrient cycling and soil communities, but the effects on soil communities are not well known. In this study we investigated nematode community response to decomposing pig cadavers ( Sus scrofa ) over a one-year period. As nematodes play key roles in soil food webs and are known to respond to disturbances and nutrient enrichment, we hypothesised that they would respond to decomposing cadavers and that this response would change over time. We compared the temporal patterns of nematode density and community structure under pig cadavers, either placed directly on the ground or hung 1 m aboveground (for effects of cadaveric fluids only), with two controls, i.e., bare soil and bags filled with soil placed on the ground (fake pigs – for microclimatic effects only). In the control and fake pig treatments nematode densities, community patterns and maturity indices did not change significantly. In contrast, density increased significantly underneath the ground and hanging pigs two weeks after the beginning of the experiment, and nematode family richness, Simpson diversity and maturity index were significantly reduced in the cadaver treatments. Most nematode families responded negatively to cadavers with the notable exceptions of Rhabditidae, Neodiplogasteridae and Diplogasteroididae. The latter two were found exclusively underneath the decomposing cadavers and are promising bioindicators of vertebrate cadaver decomposition. Even though diversity, density and communities were recovering after one year, the impact of cadavers was still significant for the maturity index. These contrasting patterns illustrate how decomposing cadavers contribute to increasing local biodiversity and suggest that soil nematodes could be used as a tool to document the presence of a decomposing cadaver, or to estimate the time elapsed since death (post-mortem interval). Patterns should, however, be compared in different settings and seasons before such a tool can be validated. [ABSTRACT FROM AUTHOR]