Spatiotemporal dynamics and underlying mechanisms of ecosystem respiration in rubber plantations: a case study in Hainan Island

Rubber plantations are an important component of tropical forest ecosystems and are emerging as crucial contributors to carbon sequestration in the tropics. However, ecosystem respiration (RECO), which constitutes an essential constraint on the carbon fixation capacity of rubber plantations, and its driving mechanisms remains unclear. Therefore, this study developed a data-driven semi-empirical model to simulate rubber plantations RECO utilising eddy covariance flux measurements and was upscaled to Hainan Island using remote sensing images and climatic data. Numerical simulations experiments analysed direct and indirect of climatic factors impacts on rubber plantations RECO. The results showed that the model accurately captured RECO trends and seasonality (R² = 0.87, RMSE = 1.27 g C m⁻² d⁻¹); in the past 19 years, RECO showed a noticeable increase, particularly in the late rainy season and the seasonality of RECO has shown a delayed pattern. The RECO in the central region (52% area) exhibited multimodal enhancement while northern and southern regions (37% area) showed oscillations or decreases. Temporally, RECO is higher in the rainy season compared to the dry season, and spatially, RECO is higher in the southern region than in the northern region. Among the climatic factors, water conditions (rainfall and air humidity) have been emerged as dominant factors (5.38%) influencing RECO, surpassing temperature (3.96%) and radiation (3.81%). In addition, climatic factors make a positive overall contribution during the dry season but perform oppositely in the rainy season. This study offers theoretical and technical insights into high carbon sink management in rubber plantations and carbon sequestration in tropical forests ecosystems.