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Long-term changes of soil nematode diversity and distribution patterns in replant peach orchard (RPO) and continuous-planting peach orchard (CPPO) were assessed to evaluate different effects on nematode community and function by RPO and CPPO, in relation to peach replant problem from the point of soil fauna. Observations were conducted on a silt loam soil, and soil sampling was performed four times through the growing season of peach trees in the period from 2006 to 2008 in Pinggu, Beijing. The result showed that RPO differed from CPPO by its higher abundance of plant feeding nematodes but lower abundance of bacterivore nematodes, as well as significantly higher values of plant parasite index but lower nematode biodiversity. Obviously, the absolute abundance of Paratylenchus in RPO was higher than that in CPPO, which could be a key factor for the peach replant problems from the part of soil nematode. Nematode function indices and weighted nematode fauna profile analysis were no significantly different in the two peach ecosystems, but they represented an indication of high disturbance, N-enriched, bacterial decomposition pathway.

Four major tea management practices (organic, pollution-free, conventional, and semi-natural) are employed in Chinese tea plantations at present. These practices can induce changes in the physiochemical parameters, microorganism community and enzyme activity in tea plantation soil. However, understanding of their effects on soil nematodes is still scarce. This study aimed to investigate whether and how different management practices affect the biodiversity, function, and structure of soil nematode communities in tea plantation habitats. The soil nematode community structures and ecological indices were determined from the soil samples collected more than 6 y after their respective farming practices were first applied, and different management practices did not greatly affect soil nematode community evenness or species diversity, but organic practice increased nematode trophic diversity, common species diversity, and species richness. Pollution-free practice considerably increased fungivorous nematodes, and both pollution-free and conventional practice decreased bacterivorous nematodes markedly in the subsurface layers of soil. Predator and omnivorous nematodes were found to be more abundant in semi-natural plantation. Organic practice was more sustainable and suitable for tea cultivation, with the greatest biodiversity, best nutrient conditions, higher and more stable C/N ratio and lower interference in the food web. [ABSTRACT FROM AUTHOR]