title: Soil respiration and carbon loss relationship with temperature and land use conversion in freeze-thaw agricultural area.
abstract: Soil respiration (Rs) was hypothesized to have a special response pattern to soil temperature and land use conversion in the freeze-thaw area. The Rs differences of eight types of land use conversions during agricultural development were observed and the impacts of Rs on soil organic carbon (SOC) loss were assessed. The land use conversions during last three decades were categorized into eight types, and the 141 SOC sampling sites were grouped by conversion type. The typical soil sampling sites were subsequently selected for monitoring of soil temperature and Rs of each land use conversion types. The Rs correlations with temperature at difference depths and different conversion types were identified with statistical analysis. The empirical mean error model and the biophysical theoretical model with Arrhenius equation about the Rs sensitivity to temperature were both analyzed and shared the similar patterns. The temperature dependence of soil respiration (Q10) analysis further demonstrated that the averaged value of eight types of land use in this freeze-thaw agricultural area ranged from 1.15 to 1.73, which was lower than the other cold areas. The temperature dependence analysis demonstrated that the Rs in the top layer of natural land covers was more sensitive to temperature and experienced a large vertical difference. The natural land covers exhibited smaller Rs and the farmlands had the bigger value due to tillage practices. The positive relationships between SOC loss and Rs were identified, which demonstrated that Rs was the key chain for SOC loss during land use conversion. The spatial-vertical distributions of SOC concentration with the 1.5-km grid sampling showed that the more SOC loss in the farmland, which was coincided with the higher Rs in farmlands. The analysis of Rs dynamics provided an innovative explanation for SOC loss in the freeze-thaw agricultural area. The analysis of Rs dynamics provided an innovative explanation for SOC loss in the freeze-thaw agricultural area.
authors.affiliation: School of Environment, State Key Laboratory of Water Environment Simulation, Beijing Normal University, Beijing 100875, China. Electronic address: wei@bnu.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Ouyang
authors.affiliation: School of Environment, State Key Laboratory of Water Environment Simulation, Beijing Normal University, Beijing 100875, China.
authors.forename: Xuehui
authors.initials: X
authors.lastname: Lai
authors.affiliation: China-ASEAN Environment Cooperation Center (CAEC), MEP, Beijing 100035, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Environment, State Key Laboratory of Water Environment Simulation, Beijing Normal University, Beijing 100875, China.
authors.forename: Heying
authors.initials: H
authors.lastname: Liu
authors.affiliation: School of Environment, State Key Laboratory of Water Environment Simulation, Beijing Normal University, Beijing 100875, China.
authors.forename: Chunye
authors.initials: C
authors.lastname: Lin
authors.affiliation: School of Environment, State Key Laboratory of Water Environment Simulation, Beijing Normal University, Beijing 100875, China.
authors.forename: Fanghua
authors.initials: F
authors.lastname: Hao
keywords: Freeze–thawing area; Land use conversion; Soil carbon dynamics; Soil respiration; Soil temperature