Analysis of the Characteristics and Influencing Factors of Carbon and Water Fluxes in the Restored Sites of Puding, Guizhou Province

This study investigates the microclimate characteristics and temporal variations in carbon and water fluxes in the naturally restored plots in Puding County, Anshun City, Guizhou Province. Continuous monitoring and collection of environmental factors through the eddy covariance system reveals the dynamic change patterns of the microclimate environment in the early stages of returning farmland to forest and the dynamic characteristics of carbon and water fluxes in the ecosystem. The results show that the study area exhibits a pronounced carbon sink capacity at the annual scale. The net ecosystem exchange (NEE) gradually increased with the extension of the recovery time, and the carbon sink intensity reached its peak during the growing season (June–August). The water use efficiency (WUE) was significantly higher in the growing season compared to the non-growing season, indicating that the WUE and carbon sequestration capacity increased simultaneously. Structural equation model (SEM) analysis revealed that latent heat flux has the most significant regulatory effect on carbon sink function. Furthermore, temperature, relative humidity, and latent heat flux have a significant positive regulatory effect on NEE (p < 0.001), while rain and soil heat flux affect carbon sink function through an indirect path. By constructing a complex meteorological carbon flux relationship network, the main regulatory mechanism of the ecosystem carbon sink in the Puding area was revealed. These findings confirm that the implementation of returning farmland to forest has effectively enhanced the carbon sequestration capacity of karst ecosystems.