Spatial Variation And Controlling Factors Of Soil Respiration And It's Temperature Sensitivity In Terrestrial Ecosystems Across China

Soil respiration is an important pathway for carbon exchange between terrestrial ecosystems and the atmosphere.The temperature sensitivity of soil respiration(Q10)is a key parameter of the interaction between the terrestrial carbon cycle and the climate system.Understanding the spatial pattern and influencing factors of soil respiration and Q10 can help to understand the feedback relationship between the carbon cycle and climate change in terrestrial ecosystems,to understand the characteristics of the regional carbon cycle in China,and to provide a parameterized basis for regional carbon cycle modelsIn this study,China's typical terrestrial ecosystem was taken as the research object.Through literature search,we collected in situ data related to soil respiration and temperature sensitivity of typical terrestrial ecosystems in China,and constructed a comprehensive data set covering soil respiration,geography,climate,soil temperature and humidity,soil physicochemical properties and other variables.The dataset includes 1162 records covering 11 ecosystem types:deciduous broadleaf forest(DBF),deciduous coniferous forest(DNF),evergreen broadleaf forest(EBF),evergreen coniferous forest(ENF),coniferous-broadleaved mixed forest(MMF),evergreen deciduous broadleaf mixed forest(MBF),bamboo forest(BAM),grassland(GRA),cropland(CRP),shrub(SHR),wetlands(WET).The spatial variability and influencing factors of soil respiration and its temperature sensitivity were analyzed and the main findings are as follows(1)The spatial variability of annual soil respiration rate(Rs)ranges from 51.13-2480 g·C·m-2·yr-1,Rs decreases with increasing latitude and altitude and increases with increasing longitude;Soil respiration rate(Rs10)is the soil respiration rate normalized to 10?.It is based on the exponential relationship between soil respiration and temperature and is widely used to compare soil respiration rates between different ecosystem types.The spatial variability of RS10 ranged from 0.09-5.55 ?mol·m-2·s-1;RS10 increased with the increase of latitude and altitude,and there was no significant relationship between RS10 and longitude.The spatial variability of soil respiration temperature sensitivity(Q10)ranges from 0.80 to 6.96,Q10 increases with the increase of latitude and altitude,but has no significant relationship with longitude(2)The annual soil respiration rate(Rs)increased with increasing mean annual temperature(MAT),mean annual precipitation(MAP),mean annual evapotranspiration(ET),soil total nitrogen content(TN),and leaf area index(LAI).A combination of climate(MAT,MAP)and soil(TN)factors explained 23%of the spatial variability of RS;The soil respiration rate RS10 decreased with the increase of MAT,ET and increased with the increase of SOC and TN,the combination of climate(NAT,MAP)and soil(SOC)explained 24%of the spatial variability of RS10.Soil respiration temperature sensitivity(Q10)decreases with increase of mean annual temperature(MAT),mean annual evapotranspiration(ET),soil carbon to nitrogen ratio(C/N),and increased with increase of AI,SOC,TN.For every 1? increase in MAT,Q10 decreases by 5%;for every 100 mm increase in ET,Q10 decreases by 12%;for every 1 unit increase in C/N,Q10 decreases by 0.02.A combination of climate(MAT,MAP)and soil(SOC)factors explained 31%of the Q10 spatial variability.(3)Soil respiration varies across vegetation types,and the degree and direction of response to environmental factors is not consistent.Annual soil respiration rate(Rs)was highest in EBF(1072.22±36.05 g·C·m-2·yr-1),lower in SHR(586.22±95.76 g·C·m-2·yr-1)and DNF(653.90±78.32 g·C·m 2·yr-1),and not significantly different between other ecosystem types;Soil respiration rate(RS10)was the highest in DNF(1.64±0.08 ?mol·m-2·s-1),lower in SHR(0.97±0.22 ?mol·m-2·s-1)and WET(0.85±0.11 ?mol·m-2·s-1).In other vegetation types,there was no significant difference Soil respiration temperature sensitivity(Q10)was the highest in DNF(3.49±0.24),and there was no significant difference among other vegetation types.Among the 11 vegetation types,Q10 decreased with the increase of MAT in DNF,EBF,ENF,DBF,MMF and GRP.Q10 increased with the increase of MAP in BAM,SHR and EBF,and decreased with the increase of MAP in MMF.Q10 increased with the increase of SOC in CRP DBF EBF MMF and ENF.Q10 increased with the increase of TN in EBF,CRP,DBF,GRA,ENF.These findings suggest that Q10 of soil respiration and temperature sensitivity space variation is mainly affected by the climate(MAT and MAP)and soil(SOC and TN)control,has little effect on other environmental factors of soil respiration and Q10.There are differences between different ecosystem types and different response to environmental factors,in the context of climate change,between different ecosystem Q10 differentiation may occur as a result,a generation of carbon cycle model needs to be incorporated into biological geographical differentiation characteristics of soil carbon decomposition,in order to improve the prediction accuracy of carbon-climate feedback.