Urban green land carbon-sink in different functional cities: The China case

Urban green land carbon-sink (UGLC) is considered as significant for carbon-emissions reduction, and it is affected by many factors such as the city function. This paper analyzes the urban green land carbon-sink in different functional cities in China to provide important references to the Chinese government for allocating the national emission reduction targets to various cities. First, we classified 269 prefecture-level cities of China into six categories of functional cities, including integrated cities, industrial cities, transportation cities, cultural and tourist cities, larger-scale cities, and resource-dependent cities by employing the methods of principal components analysis and clustering analysis. Second, we used coefficient approach to evaluate the level of annual UGLC in these six types of city from 2005 to 2014. The results show significant difference of UGLC among the six types of cities. The level of per capita UGLC in industrial cities, transportation cities, larger-scale cities, and resource-dependent cities increased between 2005 and 2014, with the average annual growth rate being of 7.16, 10.48, 3.62 and 7.22% respectively. Integrated type city is the most significant contributor to the increasing of UGLC among these six types of cities, which increased by 5.90 tons per capita in the surveyed period: from 8.34077 × 10⁻³ tons per capita in 2005 to 14.24290 × 10⁻³ tons per capita in 2014, and the level of per capita UGLC in Integrated cites is larger than the other five types of cities. Meanwhile, UGLC in cultural and tourist cities increased from 2.22569 × 10⁻³ tons per capita to 7.39556 × 10⁻³ tons per capita between 2005 and 2008, lately decreased to 2.77142 × 10⁻³ tons per capita in 2009, and finally increased slowly in the following years.