Abstract:

Consolidating and enhancing the carbon sink capacity and potential of terrestrial ecosystems is an important approach to mitigate the rise of carbon dioxide concentration and climate warming, and it is also one of the main ways to achieve China’s goal of “carbon neutrality”. To comprehensively understand the carbon sink of China’s terrestrial ecosystems and scientifically make the implementation pathways and action plans for the “carbon neutrality” goal, this review summarized the research progress on carbon sinks in the forest, shrub, grassland, desert, wetland, and farmland ecosystems, and the challenges and pathways to enhancing carbon sink in China’s terrestrial ecosystems. In the past 40 years, China’s terrestrial ecosystems have become an important carbon sink with obviously spatiotemporal difference in carbon sink intensity. The intensity increased from 0.17 Pg·a^?1 (1 Pg = 1×10¹⁵ g) during 1980—2000 to 0.20 Pg·a^?1 during 2001—2010, and is expected to reach 0.46-0.49 Pg·a^?1 during 2050—2060. The overall carbon sink intensity in eastern and southern China is higher than that in western and northern China. The carbon source/sink characteristics of various subsystems of China’s terrestrial ecosystems are also different: forests are the major carbon sink, while shrubland, wetland, and farmland have carbon sink trends, however, whether the grassland and desert have the carbon source or sink characteristics remains unclear. Overall, China’s terrestrial ecosystem has a huge potential for carbon sink in the future but there are great uncertainties. It mainly faces three types of challenges: the ecological space is limited, the carbon sequestration capacity urgently needs to be improved, and the policy mechanisms and supporting measures need to be further improved. In the future, we should carry out an in-depth study on carbon sinks of China’s terrestrial ecosystems from the following four aspects: 1）optimizing layouts of ecological spaces and scientifically implementing ecological restoration; 2）further understanding the formation mechanisms of carbon sink and improving the carbon sequestration capacity; 3）strengthening the capacity construction in investigation, monitoring, accounting and standards specification of ecosystem carbon sinks, and 4）exploring the mechanisms and pathways for realizing the value of ecological carbon sink products.

Key words: terrestrial ecosystem, enhancing carbon sink, challenge, pathway