Abstract
The land-use change is a major determinant influencing ecosystem carbon (C) patterns and nutrient cycling in subalpine forests in the Eastern Tibetan Plateau. While some results have been obtained in relation to the influence of land-use change on aboveground components, less is known about the belowground microbial communities and related processes. We assessed the structure and function of soil microbial communities following land-use change from old-growth forest (OF) to secondary forest (SF), plantation forest (PF), and grassland (GL) in the Eastern Tibetan Plateau, China. Phospholipid fatty acid profiles and enzyme activity analysis were used to determine the composition and activities of microbial communities, respectively. Significant differences in physicochemical characteristics, microbial communities, and extracellular enzyme activities in soils under different land uses were observed in this study. pH and total nitrogen (TN) in OF and SF were significantly higher than in GL. PF showed the highest soil organic C (SOC), and significantly higher than in GL. Total phosphorus (TP) and C/N ratio in PF were significantly higher than the other land-use types. OF and PF had significantly higher anaerobic bacteria than in GL. The actinobacteria in SF was significantly higher than in PF. The saprotrophic and ectomycorrhizal (SEM) fungi was significantly lower in GL than the other land-use types. Total microbial biomass and β-glucosidase activities were significantly higher in OF and SF than in GL. GL had significantly higher polyphenoloxidase activities than in OF and PF. Anaerobic bacteria, arbuscular mycorrhizal fungi and SEM fungi were positively correlated with SOC and TP, Gram+ bacteria were correlated with C/P and N/P ratio. N-acetylglucosaminidase activity was negatively correlated with anaerobic bacteria, while polyphenoloxidase activity was positively related to actinobacteria. Furthermore, redundancy analysis revealed that the microbial community composition was primarily regulated by TN and pH. This suggested that altered land-use type initiated changes in the physicochemical characteristics of the soils, which affected the composition of microbial communities and microbial enzyme activities related to nutrient cycling in this area. This provides a scientific basis for the influence mechanism of land use on composition and function of microbial communities, as well as the rational utilization and management of land resources.
Highlights
Interactions between aboveground and belowground communities may strongly affect ecosystem functioning by regulating plant community dynamics and biogeochemical processes [1,2].Belowground, soil microbial communities are treated as decomposers of organic materials, playing important roles in mediating carbon (C) and nitrogen (N) processes and nutrient availability that are critical for the growth and maintenance of plants [3,4]
The response of soil microbial community composition to land-use changes or disturbances is commonly assessed by community level phospholipid fatty acid (PLFA) profiles
Consistent with our hypothesis and findings from previous studies [7,12,13], we found that land-use type had a significant influence on soil microbial communities and microbial extracellular enzyme activities (Figures 1 and 4), in large part, due to modified soil physicochemical properties and plant community structure
Summary
Interactions between aboveground and belowground communities may strongly affect ecosystem functioning by regulating plant community dynamics and biogeochemical processes [1,2].Belowground, soil microbial communities are treated as decomposers of organic materials, playing important roles in mediating carbon (C) and nitrogen (N) processes and nutrient availability that are critical for the growth and maintenance of plants [3,4]. Interactions between aboveground and belowground communities may strongly affect ecosystem functioning by regulating plant community dynamics and biogeochemical processes [1,2]. Aboveground plant communities can substantially alter the composition, diversity, and functions of soil microbial communities by changing root system, rhizodeposition, litter chemistry, canopy structure, and subsequent influences on soil microclimate conditions and physicochemical properties [5,6]. In human-influenced landscapes, land-use changes are accompanied by changes in aboveground plant communities and soil characteristics from which aboveground and belowground interactions develop [7]. It has been recognized that such land-use-driven change is a major determinant influencing soil microbial community [8,9]. Slight changes in microbial community structure and specific microbial functions, such as extracellular enzyme activities, have been considered to alter the processes of C and
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