Litter quantity confers soil functional resilience through mediating soil biophysical habitat and microbial community structure on an eroded bare land restored with mono Pinus massoniana

Abstract

Soils have an intrinsic ability to adapt to environmental perturbations compounded by global warming and soil pollution to continuously deliver soil functions, but little is known about how a severely degraded soil regains its functional stability after restoration of vegetation. Surface soils were sampled along slopes in a long-term trial where mono Pinus massoniana was transplanted since 1987 on an eroded bare land and pine litter was either protected or removed on the slopes. We hypothesized that litter quantity would drive changes in soil properties rather than soil microbial communities, which would be main factors in controlling soil functional stability. The specific objectives of this study were: 1) to evaluate the effects of litter management on soil properties, soil microbial community structure and functional stability and 2) to explore the relative role of soil properties and microbial community structure in controlling soil functional stability. The functional stability (resistance and resilience) was determined by measuring how the short-term decomposition of added barley (Hordeum vulgare) powder changed over 28-days following copper addition and heating. Community-level physiological profiles (CLPP) and phospholipid fatty acid (PLFA) profiles were measured to characterize soil microbial community structure. Litter quantity was significantly (P < 0.05) and positively correlated with soil organic carbon (SOC) and microbial biomass carbon (SMB-C) concentration, soil structural properties (porosity and aggregate stability) and the resilience to both perturbations. Soil microbial community structure was significantly separated in two different ways. One was associated with the quantity of litter, SOC concentration and its mediated soil properties (SMB and non-capillary porosity). Another was associated with SOC quality and its mediated soil properties (aggregate stability). These biophysical soil properties (SMB, SOC and capillary porosity) were significantly correlated with the resilience to heating and the resistance and resilience to copper addition. The separations of soil microbial community structure driven by litter quality were significantly correlated with the resistance to heating and the resilience to copper addition. This result suggests that the degraded soil could regain its functional stability after re-vegetation due to the concordant development of soil biophysical habitat and soil microbial community structure through continuous organic inputs. Maintaining litter on floor against anthropogenic collection has an important ecological value.