Soil respiration and its response to climate change and anthropogenic factors in a karst plateau wetland, southwest China

Abstract

It is important to investigate the responses of greenhouse gases to climate change (temperature, precipitation) and anthropogenic factors in plateau wetland. Based on the DNDC model, we used meteorological, soil, and land cover data to simulate the soil CO2 emission pattern and its responses to climate change and anthropogenic factors in Guizhou, China. The results showed that the mean soil CO2 emission flux in the Caohai Karst Plateau Wetland was 5.89 ± 0.17 t·C·ha−1·yr−1 from 2000 to 2019, and the annual variation showed an increasing trend with the rate of 23.02 kg·C·ha−1·yr−1. The soil total annual mean CO2 emissions were 70.62 ± 2.04 Gg·C·yr−1 (annual growth rate was 0.28 Gg·C·yr−1). Caohai wetland has great spatial heterogeneity. The emissions around Caohai Lake were high (the areas with high, middle, and low values accounted for 3.07%, 70.96%, and 25.97%, respectively), and the emission pattern was characterized by a decrease in radiation from Caohai Lake to the periphery. In addition, the cropland and forest areas exhibited high intensities (7.21 ± 0.15 t·C·ha−1·yr−1 and 6.73 ± 0.58 t·C·ha−1·yr−1, respectively) and high total emissions (54.97 ± 1.16 Gg·C·yr−1 and 10.24 ± 0.88 Gg·C·yr−1, respectively). Croplands and forests were the major land cover types controlling soil CO2 emissions in the Caohai wetland, while anthropogenic factors (cultivation) significantly increased soil CO2 emissions. Results showed that the soil CO2 emissions were positively correlated with temperature and precipitation; and the temperature change had a greater impact on soil respiration than the change in precipitation. Our results indicated that future climate change (increased temperature and precipitation) may promote an increase in soil CO2 emissions in karst plateau wetlands, and reasonable control measures (e.g. returning cropland to lakes and reducing anthropogenic factors) are the keys to controlling CO2 emissions.