Relationships between Soil Nematode Communities and Soil Quality as Affected by Land-Use Type

Researchers have used both soil nematode data and soil multifunctionality data as indicators of soil quality. However, the relationship between soil nematodes and soil multifunctionality is poorly understood. This study explored the relationship between soil nematode properties and soil multifunctionality in different land-use types in a subtropical karst region of Southwest China. We selected the following five typical land-use types that differ in the degree of soil disturbance: cropland (maize-soybean), sugarcane, mulberry, forage grass, and forest. Soil multifunctionality was calculated based on bulk density (BD), soil pH, the ratio of soil organic carbon to total nitrogen (C: N), the contents of soil water (SWC), soil total nitrogen (TN), soil organic carbon content (SOC), calcium (Ca), magnesium (Mg), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), ammonium nitrogen (AN), and nitrate nitrogen (NN). We found that the abundance, Simpson dominance index, and metabolic footprint of soil nematodes were highest in the forest, followed by sugarcane, cropland (maize-soybean) and forage grass, and mulberry. Soil multifunctionality was significantly higher in the forest than in the other land-use types. Soil multifunctionality was positively correlated with the abundance of total nematodes and all nematode trophic groups except omnivores. A random forest model revealed that the dominant nematode genera (i.e., Coomansus and Acrobeloides ) and the rare genera (i.e., Wilsonema and Heterocephalobus ) were closely associated with soil multifunctionality. Our results suggest that the soil nematodes (especially keystone genera) may mediate the effects of ecosystem disturbance on soil multifunctionality. These findings increase our understanding of the relationships between soil organisms and soil multifunctionality.