The relative contributions of forest growth and areal expansion to forestbiomass carbon

[摘要] Forests play a leading role in regional and global terrestrial carbon (C)cycles. Changes in C sequestration within forests can be attributed to arealexpansion (increase in forest area) and forest growth (increase in biomassdensity). Detailed assessment of the relative contributions of arealexpansion and forest growth to C sinks is crucial to reveal the mechanismsthat control forest C sinks and it is helpful for developing sustainable forestmanagement policies in the face of climate change. Using the ForestIdentity concept and forest inventory data, this study quantified the spatial andtemporal changes in the relative contributions of forest areal expansion andincreased biomass growth to China's forest biomass C sinks from 1977 to2008. Over the last 30 years, the areal expansion of forests has been a largercontributor to C sinks than forest growth for planted forests in China(62.2 % vs. 37.8 %). However, for natural forests, forest growth has made alarger contribution than areal expansion (60.4 % vs.39.6 %). For allforests (planted and natural forests), growth in area and density hascontributed equally to the total C sinks of forest biomass in China(50.4 % vs. 49.6 %).The relative contribution of forest growth ofplanted forests showed an increasing trend from an initial 25.3 % to61.0 % in the later period of 1998 to 2003, but for natural forests, therelative contributions were variable without clear trends, owing to thedrastic changes in forest area and biomass density over the last 30 years.Our findings suggest that afforestation will continue to increase the C sinkof China's forests in the future, subject to sustainable forest growth afterthe establishment of plantations.

[学科分类] 地球化学与岩石