浙江省生态公益林碳储量和固碳现状及潜力

生态公益林是为保护和改善人类生存环境,维持生态平衡而建立的。以浙江省的生态公益林为研究对象,共调查和估算了全省21个县149个样地(年龄从5a到50a),包括常绿阔叶林、针阔混交林、马尾松林和杉木林4种主要林型的碳储量和碳平衡。结果说明:浙江省生态公益林生态系统碳密度的加权平均值为164.43tC.hm-2;其中常绿阔叶林生态系统碳储量最高,达216.18tC.hm-2;针阔混交林其次,达181.36tC.hm-2;针叶林最低。浙江省森林以幼龄林(小于30a的占87.5%)和马尾松林(大于55%)为主离成熟状态还相差很远,尤其是针叶林远低于全国平均水平和中高纬度地区碳密度。全省生态公益林净生态系统生产力加权平均得0.08tC.hm-.2a-1,在碳积累上还有很大的潜力。通过封育改造、择伐补阔或以灌促阔等森林管理措施,加快针叶林向针阔混交林直至常绿阔叶林演替,将最大化中国亚热带地区的幼林或受干扰森林的未来碳储量(最高增长31.44%),并成为较大的碳汇。

Carbon storage and its sequestration potential by ecological service forest in Zhejiang

Carbon storage in the terrestrial ecosystem, especially in the forest ecosystem, is an important approach for maintaining carbon balance in the world. Carbon storage of the forest ecosystem usually consists of three pools, i.e. vegetation, forest floor and soil. Ecological service forest (ESF) has been established to maintain ecological processes and protect the environment. The main objective of this study was to evaluate the contribution of these four types ESF in Zhejiang Province. Zhejiang Province is a region with fast growing economy and a good ecological environment, an estimation of carbon storage and balance in this province will set up as a good model in the future for other provinces in similar cases, and a scientific foundation for the policy making about the forest development and a mitigation strategy for climate change. Zhejiang Province is located south side of the Yangtze River Delta, along the eastern coast of China. The region has a long land-use history, and experienced thousands of years human activities and disturbance, most of the native forest vegetation has been destroyed, especially in the last century. We have sampled 149 stands ranging from 5 to 50 years old and covering 101,800 km2, in Zhejiang Province. These samples included four main types of ESF: evergreen broad-leaved forest (ESF-EF), coniferous and broad-leaved mixed forest (ESF-MF), pine (Pinus massoniana) forest (ESF-PF), and Chinese fir (Cunninghamia lanceolata) forest (ESF-CF). The ESF in Zhejiang Province has been estimated with the average of 164.43 tC•hm-2 carbon storage, in which the ESF-EF and ESF-MF were averaged to be 216.18 and 181.36 tC•hm-2, respectively. ESF in Zhejiang is still young (under 30-year-old account for 87.5%) and pine forest (over 55%) mainly result in low carbon storage less than that of China average and mid-high latitude level. Moreover, the net ecosystem production (NEP) values varied greatly among the four main forest types at the mid and high latitudes in Zhejiang Province; and our observation has shown that the ESF-PF acts as a minor carbon source (-0.66 tC•hm-2•a-1), NEP of the ESF-CF is near to zero(0.17 tC•hm-2•a-1), ESF-MF acts as a minor carbon sink (0.31 tC•hm-2•a-1), and ESF-EF as a large carbon sink (1.11 tC•hm-2•a-1). The NEP of ESF in Zhejiang is weight-averaged about 0.08 tC•hm-2•a-1. We estimated carbon balance for four forest types in subtropical zone through field survey data firstly. Carbon budget of four forest types calculated show that evergreen broad-leaved forest are better than coniferous and broad-leaved mixed forest in terms of the carbon sequestration benefit. Most ecological service forest in Zhejiang Province is still relatively young, so there is a great potential in future for carbon sequestration in this province. Comparing to carbon storage potential and carbon balance for the main forest types in this region, we found that forest management practices such as enclosure, selective cutting and promoting by shrub for ecological service forest should be reformed to accelerate the succession of coniferous forest into evergreen broad-leaved forest. It could maximize (31.44% at best) the carbon storage of young or disturbed forest in future for a larger carbon sinks in subtropical regions of China.