Stage characteristics, spatial differences and dynamic evolution of crop carbon sink in Hubei Province based on the crop data from 1997 to 2022

Hubei Province is a major agricultural province in China. The scientific measurement of the carbon sink of crops in Hubei Province, which clarifies the baseline, is of significant importance for carbon sink trading and the development of low-carbon agriculture. The study measured the carbon sink of crops in Hubei Province from 1997 to 2022, employing the Dagum Gini coefficient, Kernel density estimation, and Markov chains, to explore the regional differences and dynamic evolution characteristics of the crop carbon sink in Hubei Province. The results indicated that from 1997 to 2022, the crop carbon sink in Hubei Province exhibited a fluctuating upward trend, presenting a "W" shaped distribution with an average value of 120.853 million tons, with grain crops being the primary contributor to the crop carbon sink. Under the "dual carbon" context, an analysis of three major regions and cities (prefectures) in Hubei Province revealed that from 1997 to 2022, the eastern region of Hubei Province ranked first among the three major regions in terms of crop carbon sink. The Dagum Gini coefficient analysis showed certain regional differences in the crop carbon sink in Hubei Province, mainly coming from ultra-variable density, with an average contribution rate of 53.58%. The total crop carbon sink in Hubei Province exhibited strong stability and demonstrated certain characteristics of club convergence. Finally, this paper proposed the development of methodologies and standards for crop carbon sink accounting, the formulation of differentiated policies for increasing agricultural carbon sink, and suggestions for exploring countermeasures for carbon sink trading.