Chen Xiangang, Luo Yunjian, Zhou Yongfeng, Lu Mei
School of Environmental Science and Engineering, Southwest Forestry University, Kunming, Yunnan, China.
Department of Ecology, School of Horticulture and Plant Protection, Yangzhou University, Yangzhou, Jiangsu, China.
PLoS One. 2016 Mar 9;11(3):e0150992. doi: 10.1371/journal.pone.0150992. eCollection 2016.
The Grain for Green Program (GGP) is the largest afforestation and reforestation project in China in the early part of this century. To assess carbon sequestration in stands under the GGP in Southwest China, the carbon stocks and their annual changes in the GGP stands in the region were estimated based on the following information: (1) collected data on the annually planted area of each tree species under the GGP in Southwest China from 1999 to 2010; (2) development of empirical growth curves and corresponding carbon estimation models for each species growing in the GPP stands; and (3) parameters associated with the stands such as wood density, biomass expansion factor, carbon fraction and the change rate of soil organic carbon content. Two forest management scenarios were examined: scenario A, with no harvesting, and scenario B, with logging at the customary rotation followed by replanting. The results showed that by the years 2020, 2030, 2040, 2050 and 2060, the expected carbon storage of the GGP stands in Southwest China is 139.58 TgC, 177.50-207.55 TgC, 196.86-259.65 TgC, 240.45-290.62 TgC and 203.22-310.03 TgC (T = 1012), respectively. For the same years, the expected annual change in carbon stocks is 7.96 TgCyr-1, -7.95-5.95 TgCyr-1, -0.10-4.67 TgCyr-1, 4.31-2.24 TgCyr-1 and -0.02-1.75 TgCyr-1, respectively. This indicates that the stands significantly contribute to forest carbon sinks in this region. In 2060, the estimated carbon stocks in the seven major species of GGP stands in Southwest China are 4.16-13.01 TgC for Pinus armandii, 6.30-15.01 TgC for Pinus massoniana, 11.51-13.44 TgC for Cryptomeria fortunei, 15.94-24.13 TgC for Cunninghamia lanceolata, 28.05 TgC for Cupressus spp., 5.32-15.63 TgC for Populus deltoides and 5.87-14.09 TgC for Eucalyptus spp. The carbon stocks in these seven species account for 36.8%-41.4% of the total carbon stocks in all GGP stands over the next 50 years.
退耕还林工程是本世纪初中国规模最大的造林和再造林项目。为评估中国西南地区退耕还林工程林分的碳固存情况，基于以下信息对该地区退耕还林工程林分的碳储量及其年变化进行了估算：（1）收集了1999年至2010年中国西南地区退耕还林工程中各树种每年的种植面积数据；（2）建立了退耕还林工程林分中各树种的经验生长曲线和相应的碳估算模型；（3）林分相关参数，如木材密度、生物量扩展因子、碳含量以及土壤有机碳含量变化率。研究了两种森林经营情景：情景A，不进行采伐；情景B，按常规轮伐期采伐后再造林。结果表明，到2020年、2030年、2040年、2050年和2060年，中国西南地区退耕还林工程林分的预期碳储量分别为139.58太克碳（TgC，1 T = 10¹²）、177.50 - 207.55 TgC、196.86 - 259.65 TgC、240.45 - 290.62 TgC和203.22 - 310.03 TgC。对于相同年份，碳储量的预期年变化分别为7.96 TgC·yr⁻¹、-7.95 - 5.95 TgC·yr⁻¹、-0.10 - 4.67 TgC·yr⁻¹、4.31 - 2.24 TgC·yr⁻¹和-0.02 - 1.75 TgC·yr⁻¹。这表明这些林分对该地区的森林碳汇有显著贡献。2060年，中国西南地区退耕还林工程林分中七个主要树种的估算碳储量分别为：华山松4.16 - 13.01 TgC、马尾松6.30 - 15.01 TgC、柳杉11.51 - 13.44 TgC、杉木15.94 - 24.13 TgC、柏木属28.05 TgC、美洲黑杨5.32 - 15.63 TgC、桉树5.87 - 14.09 TgC。在未来50年里，这七个树种的碳储量占所有退耕还林工程林分总碳储量的36.8% - 41.4%。
