Abstract:
In order to reveal the temporal and spatial variation characteristics of soil CO
2 and its influencing factors under different land use types in the typical karst areas, the CO
2 concentration of 5 cm, 20 cm, 40 cm, and 60 cm depths of six typical sites in the Shuanghe Cave, Suiyang, Guizhou was detected from January 2018 to August 2019. And the main factors affecting the spatial and temporal changes of soil CO
2 were investigated. The results showed that: (1) The soil CO
2 concentration under different land types showed obvious seasonal variation characteristics, being higher in summer and autumn and lower in winter and spring. The annual average concentration of CO
2 was the highest in October (23276 ppm), and was the lowest in January (6602 ppm). (2) The soil CO
2 concentration under different land types decreased in the order of dry land (19967 ppm) > grassland (17098 ppm) > shrub land (15054 ppm) > forest land (11494 ppm) > returning farmland to forestland (10529 ppm) > wasteland (6147 ppm). The soil CO
2 concentration in the forest land showed a decreasing first and then increasing trend with soil depths, while the CO
2 concentrations in the other five land types were increased with soil depths. (3) The soil CO
2 concentration was positively correlated with soil temperature, soil moisture content, organic carbon content, and porosity, with a correlation coefficient of 0.406, 0.252, 0.382, and 0.703, respectively. Correlation analysis showed that soil temperature and soil porosity had significant effects on the generation and preservation of CO
2 in soil. The research results are of great significance for evaluating the effects of land types in typical karst areas on soil carbon sources and sinks, and would provide a certain theoretical reference for investigating the vertical carbon cycling in a key karst zones.