Isolating the contributions of climate change and human activities to vegetation net primary productivity at the spatial unit scale: a case study in Hunan Province, China

Taking Hunan Province, China, as the study area, this paper delineated 12 spatial units by integrating the carbon budget and major functional zoning to support China's dual-carbon goals and territorial planning. The Thornthwaite Memorial model and residual analysis were applied to quantify net primary productivity (NPP) dynamics and isolate the contributions of climate change and human activities from 2000 to 2024. Results showed that the multiyear mean NPP was 641.22 g C m−2 yr−1 with a fluctuating upward trend. The western ecological functional areas have a higher NPP, while the urbanized areas in the east have a lower NPP. Climate and human contributions to NPP variations were 37.51% and 62.49%, respectively. Human activities exert a dominant influence on units characterized by high energy consumption and carbon emission, whereas climate change prevails in units with strong carbon sink functions. These findings provide spatially explicit insights for ecological conservation and carbon management under coupled human–natural systems.