Donor-side Valuation of Forest Ecosystem Services in China During 1990–2020

China’s forest ecosystem service supply has faced intense pressure during the last few decades, calling for a unified valuation on a long timescale to reveal its temporal and spatial changes. Yet, existing studies are confined to static valuations for a single year at the regional scale, while a temporal–spatial investigation for the ecosystem service value of China’s various forest types at the national scale is currently lacking. This study quantified the ecosystem service value of China’s various forest types during 1990–2020 and analyzed its temporal–spatial variations. As a supplement to emergy analysis, a unified assessment framework based on cosmic exergy as a biophysical metric has been proposed for ecosystem service valuation. Results showed that forests in southwest, southeast, and northeast China were the major providers of ecosystem services. From 1990 to 2020, although the aggregated value of China’s forest ecosystem service increased by only 4