Influence of different ecosystems on the soil moisture and karst effect in Luota, West Hunan Province of China

Abstract

In this paper, we study the soil CO2 concentration, soil respiration rate, dissolution rate and soil water content of different ecosystems in Luota, western Hunan Province, China, using the CO2 gas monitoring tube method, alkali absorption method, standard specimen method and drying method. The results show the following: the soil CO2 concentrations of the different depths have the same change trends in the forest and bush ecosystems. In spring, autumn and winter, the trends increase as the soil layer deepens, while in summer they first reduce and then increase as the soil layer deepens. However, the seasonal change dynamics differ slightly, and the soil CO2 concentrations of the forest ecosystem at the different depths and in the different seasons are greater than those of the bush ecosystem. From the perspective of comparing the full-year soil CO2 concentration, the full-year soil CO2 concentrations of the forest ecosystem at the depths of 10, 20 and 40 cm are, respectively, 1.66, 1.59 and 1.90 times those of the bush ecosystem. From the perspective of the soil respiration rates of the different seasons, the seasonal change trends of the forest and bush ecosystems are the same, both being summer > autumn > spring. The soil respiration rates of the forest ecosystem in the different seasons are higher than those of the bush ecosystem, and in spring, summer and autumn the respective soil respiration rates of the forest ecosystem are 2.09, 3.46 and 3.06 times those of the bush ecosystem. At the different depths, the dissolution rates have the same change trends in the forest and bush ecosystems, and the dissolution rates at the depth of 15 cm are both greater than those on the ground. At the same depth, the dissolution rate of the forest ecosystem is greater than that of the bush ecosystem, and the dissolution rates on the ground and at the depth of 15 cm are, respectively, 1.11 and 2.57 times those of the bush ecosystem. The soil water content of the forest ecosystem is 1.07 times of that of the bush ecosystem, and the soil water content stability of the forest ecosystem is higher, indicating that the forest ecosystem has a better karst effect.