资源环境科技发展态势分析平台

Tree species and forest age are two key variables affecting timber production and carbon sequestration in forest ecosystems. In this study, in Jiangxi province of eastern China, by a thorough investigation of 179 subtropical forest stands in a 16.7 x 10(6) ha area with similar climatic conditions and past land-use history, we systematically examined biomass of live aboveground tree, forest floor litter, shrub and herb as well as soil organic carbon (SOC) content (0-10, 10-30 and 30-100 cm depths) to compare differences among five major vegetation types (Chinese fir, masson pine, single-species broadleaves, mixed conifers-broadleaves, and mixed-species broadleaves), and between age classes (below vs above 30 years of stand age). Tree species and stand age both had significant effects. Among the five forest types, mixed-species broadleaved forests had remarkably highest timber productivity, SOC content and storage in the 0-100 cm depth and total C store in the age group of above 30 years. Coniferous stands had generally higher forest floor biomass than broadleaved stands in the age group of below 30 years; this trend was opposite for mineral soil C in the age group of above 30 years. Stand age significantly affected aboveground timber production for all the tree species; this effect was weaker on belowground soil C, as broadleaves exhibited increases in SOC content with stand age while conifers did not. Our results suggest that long-term continuity ( > 30 years) of mixed-species broadleaves could be an optimal strategy for forests in subtropical region of China. This study contributes to a better understanding of the effects of management practices on forest ecosystems.