Multiple satellite-based analysis reveals complex climate effects of temperate forests and related energy budget

Forest conversion-driven biophysical processes have been examined in various case studies that largely depend on sensitivity analysis of climate modeling. However, much remains unknown in the real world due to the complicated process and uncertainty in magnitude, especially in the temperate bioclimate regions. This study applied satellite-based observation to investigate the biophysical climate response to potential forest conversion in China, especially on the spatial and temporal patterns and underlying mechanisms. We evaluated the differences of land surface temperature (LST) between adjacent forest and cropland, in terms of the latitudinal and seasonal patterns. Compared to cropland, the temperate forest to the south of 40 degrees N showed the cooling effect of -0.610.02 degrees C (95% confidence interval, and hereafter), and it presented the warming effect of 0.480.06 degrees C to the north of 48 degrees N (the transition zone was between 40 degrees N and 48 degrees N). Seasonal analysis further demonstrated that the cooling effects of temperate forest in China in spring (March, April, May), summer (June, July, August), and autumn (September, October, November) were -0.530.02 degrees C, -0.550.02 degrees C, and -0.30 +/- 0.02 degrees C, respectively, while the forest caused the warming effect of 0.10 +/- 0.04 degrees C in winter (December, January, February). However, the biophysical climate response to forest conversion in temperate regions was complex and showed highly spatial and temporal heterogeneity. We further assessed the role of two major biophysical processes, i.e., albedo and evapotranspiration (ET), in shaping land surface temperature from surface energy budget perspective. Results showed that the latitudinal, seasonal, and spatiotemporal patterns of LST was determined by the net effect of ET-induced latent heat changes and albedo-induced solar radiation absorption changes.