Grazing by large herbivores improves soil microbial metabolic activity in a meadow steppe

Abstract

AbstractLarge herbivores grazing is a major disturbance that can cause significant changes of soil environment in grassland ecosystems. However, it remains unclear how soil microbial metabolic activity responses to different grazing intensities. We analyzed the relationships between soil microbial carbon source utilization and grazing intensity, and further assessed the main factors determining soil microbial metabolic activity in a meadow steppe. Soil samples were analyzed along different grazing intensities (no grazing, light grazing and heavy grazing) with community‐level physiological profiles (CLPP) using Biolog Eco‐plates incubation to estimate soil microbial carbon source utilization patterns. Redundancy analysis (RDA) was performed to explore the major factors influencing soil microbial metabolic activity in a five‐year grazing grassland in northeast of China. Grazing significantly improved soil microbial community carbon utilization and increased utilization of carbohydrates, amino acids, phenolic acids and amines, while significantly decreased utilization of carboxylic acids. Among edaphic properties and plant traits, plant density, total biomass (TB), soil water content (SW) and C:N ratio (C/N) were main driving forces contributing to the carbon source utilization structure of the soil microbial communities. Soil microbial metabolic activity was promoted by grazing through altering plant traits and abiotic soil properties, and soil‐related factors were primary and direct driving force for soil microbial metabolic activity in grasslands of northeast China. The present study demonstrated differential soil microbial responses along grazing intensities and has important applications for better management practices in the grassland ecosystem.