Abstract: Global climate change is becoming increasingly serious, and thereby green and low-carbon transformation is imperative. Quantification of terrestrial ecosystem carbon sink capacity is helpful to acquiring detail information about carbon sink resources, identifying the important spaces for carbon sink, and formulating strategies for enhancing carbon sink capacity. We evaluated carbon sink capacity of three counties in southwest Jiaxing based on the two factors, namely carbon storage and net ecosystem productivity. We further explored the differences in carbon sink capacity under different land use patterns. The results showed that the total carbon storage of the three counties in southwest Jiaxing was 1.54 Tg, with an average carbon density of 35.06 t·hm^-2. The high-value areas were the mountain forest land in the south and the land for economic crops in the north. The closer to the city center, the lower the carbon storage and carbon density. The average net ecosystem productivity was 463.34 g·m^-2·a^-1. The carbon source areas were mainly concentrated near the urban built-up areas and along the Qiantang River in the south, while the areas with high carbon sink values were mainly located in the southern mountain forest lands and some scattered woodlands in Haiyan County. Overall, the ranking of carbon sink capacity of land use types was forest land > land for economic crops > land for green and open space. The higher the degree of fragmentation, decentralization and marginalization, the lower the carbon sink capacity of terrestrial ecosystems. Strategies for enhancing carbon sink capacity were proposed for different land use types.

Key words: ecosystem carbon sink, carbon storage, net ecosystem productivity, spatial distribution