Study on forest volume-to-biomass modeling and carbon storage dynamics in China

Abstract

<p indent="0mm">Estimating forest biomass (in forest volume per unit area) is a significant forest carbon estimation method. However, models of forest volume-to-biomass were established based on the limited tree species at a local scale. Therefore, it is significant to establish regional and national biomass models. According to sampling populations and climate differences in forest resource inventory, China was divided into seven regions. Using the national biomass estimated data obtained in this study, we established forest volume-to-biomass regression models for 25 tree species and 21 forest stands of conifer, broad-leaved, and conifer-broad-leaved mixed forest in China. This study aims to reveal the changing patterns and causes of forest carbon storage and its contribution to carbon sinks across the nation and different regions in the past <sc>70 years.</sc> Based on the established regression models and data of the forest resource inventory and statistics within 11 periods from 1949 to 2018, forest carbon storage and carbon source/sink capacity in China were systematically calculated. Results obtained showed that carbon change in various regions was significantly different. From 1949 to 1976, the carbon in China’s forest resources decreased significantly; the average annual decrease was 0.52%. The total carbon in forest resources was 0.13%, and the reduction lasted for a long time in Northeast and Southwest China. From 1977 to 2018, the standing carbon and total carbon, which was 3.80% and 3.14%, respectively, increased each year, and the growth rate was the largest between 1999 and 2003. In 2018, the total carbon stored increased from 4.050 PgC (1 Pg=<sc>10¹⁵ g)</sc> to 8.362 PgC (an increase of 106.46%), and carbon storage of the forest increased from 3.938 PgC to 7.669 PgC (an increase of 94.74%). The lowest carbon density during 1973–1976 was <sc>35.24 Mg/ha</sc> (1 Mg=10⁶ g), which increased to 42.63 Mg/ha between 2014 and 2018 and continued to increase. In the future, China’s carbon sink potential will be huge.