黄土高原退耕方式与年限对土壤呼吸及其温度敏感性的影响OA北大核心CSTPCD

Soil respiration is a key process in the carbon cycle of terrestrial ecosystems.It is an important prerequisite for improving soil carbon sink capacity to clarify the effects of land conversion patterns and years on soil respiration,and its temperature sensitivity.In this study,the soil respiration rates of 20-year cultivated land,3-,6-and 10-year apple orchards and grassland in Loess Plateau was monitored in situ from July to December 2018,and the temperature sensitivity of different soils was estimated.The partial least square-structural equation model(PLS-SEM)was used to analyze the key factors affecting soil respiration and its temperature sensitivity.The results showed that the contents of soil organic carbon and total nitro-gen decreased first and then increased with the increase of the years of returning farmland to forest/grass-land,while the apple forest was in opposite.During the monitoring period,the average soil respiration rate of grassland was 2.73-4.65 μmol·m-2·s-1,and that of apple orchard was 1.07-3.13 μmol·m-2· s-1.The soil respiration rate of grassland was significantly higher than that of apple orchard after 3 and 6 years of restoration(P＜0.05).The temperature sensitivity of soil respiration ranged from 1.477-4.055,and there was no significant difference in soil respiration temperature sensitivity among different conver-sion patterns.The results of applying PLS-SEM showed that soil factors explained 34.4％of the variation of soil respiration and its temperature sensitivity.Compared with chemical and biological factors,physical factors such as soil moisture and temperature had more significant effects on soil respiration and its tem-perature sensitivity.Studies have shown that in the short term(0-6 years)after returning farmland to forest/grassland,the carbon sequestration potential of apple forest is greater,but when the years of retur-ning farmland are longer(6 years later),grassland is more conducive to soil carbon sequestration.