Local water-heat-carbon impacts of forest changes based on satellite observations and statistical modeling in two forest cities of the hilly areas in southern China

Changes in forest cover significantly influence carbon-climate dynamics, yet integrated assessment frameworks that connect water-heat-carbon interactions are still limited for subtropical hilly regions. This study presents a spatiotemporal framework for evaluating the impact of forest changes on water-heat-carbon and biophysical processes. Based on effective moving-window samples (Hangzhou: 168; Zhaoqing: 175), we employed partial least squares structural equation modeling (GOF: 0.81/0.71), variance partitioning analysis, and hierarchical partitioning (R2 : 0.79/0.73) to investigate their interactive relationships and evaluate their accuracy. Results indicate that forest changes exert consistent effects on water-heat-carbon dynamics and biophysical processes in Hangzhou and Zhaoqing, with afforestation and deforestation yielding opposite impacts. The net changes in land surface temperature caused by forest changes from 2000–2010 and 2010–2020 were −0.23 ± 0.40°C/–0.11 ± 0.29°C for Hangzhou and 0.4 ± 0.25°C/–0.49 ± 0.38°C for Zhaoqing, respectively. These changes were significantly larger than the variations in air temperature. Precipitation changes were 13.02 ± 4.66 mm/2.68 ± 5.09 mm and 2.88 ± 1.24 mm/0.62 ± 1.45 mm, with afforestation yielding a greater precipitation increase effect. Carbon stock changes were −8.17 ± 1.79 t/ha/–1.59 ± 1.95 t/ha and −2.76 ± 0.99 t/ha/–2.92 ± 1.28 t/ha. Deforestation resulted in greater carbon losses. We found that the combined effects of biophysical mechanisms exert a greater influence than their individual contributions, and evapotranspiration primarily controls water-heat-carbon interactions. Our study demonstrates that careful management of hilly forests and urban areas is crucial for enhancing carbon sequestration and stabilizing the regional climate. Urban planning should focus on identifying priority afforestation areas. While fully considering the water-heat-carbon benefits of forests, it is also necessary to strengthen forest supervision and establish a monitoring network to achieve sustainable development.