The continent-scale variations in soil microbial respiration in forest ecosystems: diverged pattern and mechanism
Peng Tian 1,2, Xuechao Zhao 2,3, Shengen Liu 2, Zhaolin Sun 2,3, Yanli Jing2, Qingkui Wang 1,2
1 School of Forestry & Landscape Architecture, Anhui Agricultural University, Hefei 230036 China
2 Huitong Experimental Station of Forest Ecology, CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang 110016 China
3 University of Chinese Academy of Sciences, Beijing 100049 China
Running title : Spatial variation in Rm at different scales
Abstract :
Globally rising soil microbial respiration (Rm) is a key process controlling the soil-to-atmosphere CO2 flux, yet its spatial variation and underlying mechanism at different scales is still poorly understood. A novel experiment based on the annual mean temperature of soil origin sites along a 4,200 km north–south transect of China forests revealed a hump-shaped relationship between Rm and latitude with a latitudinal threshold of 32.5°N. Microbial variables were more important in shaping Rm’ spatial variation at the continental scale than at the regional scales, but soil physicochemical property had comparably unique importance at different scales. Labile organic C was the most important factor in regulating the Rm’s variation at the continent and in the latitude > 32.5°N region, but fungi biomass was the most important factor in the latitude < 32.5°N region. Overall, our findings suggest different controlling factors of Rm’s variations on either side of the latitudinal threshold.
Keywords: heterotrophic respiration, soil organic carbon decomposition, spatial pattern, latitudinal threshold, labile organic carbon, soil microbial community