近30年土地利用变化对新疆森林生态系统碳库的影响

土地利用及其变化是导致森林生态系统碳库变化最重要的因素。以植树造林面积、森林产品收获产量及林地转移面积为基础数据,采用《LULUCF指南》中数据分层的碳源汇计量方法,分析了1975-2005 年期间三种土地利用方式对新疆森林碳库的影响。1975 年新疆森林总碳库估算值为720.02 Tg,其中土壤碳库为528.82 Tg。近30 年土地利用变化对其碳库的影响总体表现为碳汇,固碳量为48.15 Tg,与1975 年碳库相比,森林碳储量增长了6.69%。植树造林表现出强烈的碳汇功能,总固碳量为54.24 Tg。森林采伐是最主要的碳释放来源,共释放碳5.42 Tg。林地转移呈现微弱的碳释放特征,共排放为0.66 Tg。研究结果表明,土地利用变化对该区域森林碳库具有明显的增汇效应。本研究将有利于进一步深化人类活动对区域碳平衡影响的认识。

Sources and sinks of carbon from forest land use change in Xinjiang,China during 1975-2005

Changes in forest land use contribute to the carbon source in most tropical regions due to large-scale deforestation but are poorly documented for arid forest ecosystem. According to "Guidelines for Land Use, Land-use Change and Forestry" documented by IPCC, we estimated sources and sinks of carbon from forest land use change between 1975 and 2005 in Xinjiang, China. The results indicated that: (1) the carbon stock of forest ecosystem in Xinjiang is 720.02 Tg in 1975, whereas the vegetation carbon stock is 191.20 Tg, and soil carbon stock is 528.82 Tg; (2) Generally, the effect of forest land use change in Xinjiang performed as a carbon sink, with a total carbon sequestration of 48.15 Tg, and increased by 6.69% compared with the total carbon stock of 1975. The accelerated afforestation led to a strong carbon sequestration (54.24 Tg), while the deforestation showed a main carbon source, releasing 5.42 Tg. The woodland transferring performed as a weak carbon source, releasing 0.66 Tg; (3) We recommend that some efficient measures should be taken on raising the quality and quantity of forest resources in the future to enhance the forestry carbon sequestration in Xinjiang. Therefore, this can offset the carbon loss from industrial activities so as to provide sufficient space for the sustained and healthy economic development in Xinjiang. This study will be conducive to further deepen the understanding of the influence of human activity on regional carbon balance.