【目的】通过构建植被-土壤全生态系统碳储量评估体系,系统估算江苏省森林生态系统的碳储存能力,揭示当前江苏省森林碳储量现状和问题所在,为制定有效的森林资源管理和碳汇管理政策提供科学依据。【方法】以我国第九次(2014—2018)森林资源清查数据为基础,结合野外典型样地调查数据和相关文献数据,采用蓄积量-生物量换算因子连续函数估算模型,估测江苏省森林资源碳储量、碳密度分布特征,比较分析不同优势树种、龄组、林分起源和林种类型碳储量的分布格局,并根据生态系统各空间层次的生物量密度和含碳系数以及植被面积估算林下灌木层、草本层、凋落物层碳储量;根据不同土层深度的土壤有机碳含量和容重估算1 m深度土壤层碳储量。【结果】①江苏省不同森林类型植被总碳储量为4.752 36×10⁷ t,其中乔木林碳储量占总碳储量的68.26%;碳密度为25.49 t/hm²,其中竹林碳密度最高,为35.75 t/hm²。②优势树种中以杨树(Populus spp.)占比最高,其碳储量占总碳储量的56.90%。乔木林不同龄组的碳储量以中幼龄为主,从大到小排序为中龄林>幼龄林>近熟林>成熟林>过熟林;碳密度表现为随着林龄的增长而增加的趋势。③人工林碳储量高于天然次生林碳储量,人工林碳储量占总碳储量的96.41%,达3.127 06×10⁷ t。④不同林种碳密度大小为用材林>防护林>特用林>经济林,碳储量大小顺序与之相同,用材林占比66.50%。⑤从生态系统来看,江苏省森林生态系统总碳储量为2.080 4×10⁸ t,森林生态系统碳储量空间分布特征,大小排序为土壤层>乔木层>灌木层>草本层>凋落物层。土壤层碳储量为1.588 8×10⁸ t,占森林生态系统总碳储量的76.37%,乔木层次之,占比为16.16%。【结论】江苏省森林碳储量呈显著增长趋势,森林地上部分碳储量和地下土壤碳储量的比例约为3∶7。但与全国平均水平相比,江苏省森林碳密度相对较低,且多以人工林分为主,杨树林面积占比过高,林分以幼中林为主。研究结果可为提高森林的单位面积碳固持能力提供数据参考,有利于森林资源的保护和可持续发展,特别是保护林下灌草和凋落物层,可增加土壤碳储量,构建合理的森林经营模式。

【Objective】By constructing a vegetation-soil whole-ecosystem carbon storage assessment system, the carbon sequestration capacity of the forest ecosystem in Jiangsu Province is systematically evaluated. The current status and existing issues of forest carbon storage in Jiangsu Province are revealed, providing a scientific basis for formulating effective forest resource management and carbon sink management policies.【Method】Based on the 9th National Forest Resource Inventory data of China (2014—2018), combined with field survey data of typical plots and relevant literature data, the continuous function estimation model of volume-biomass conversion factor was used to estimate the carbon storage and carbon density distribution of forest resources in Jiangsu Province. The distribution patterns of carbon storage among different dominant tree species, age classes, stand origins, and forest types were compared and analyzed. Carbon storage of understory shrub layer, herb layer, and litter layer was estimated based on the biomass density, carbon coefficient of each spatial layer in the ecosystem, as well as vegetation area. In addition, carbon storage of the one-meter-deep soil layer was estimated based on soil organic carbon content and bulk density at different soil depth.【Result】(1) The total vegetation carbon storage of different forest types in Jiangsu Province is 4.752 36×10⁷ t,among which arbor forest accounts for 68.26% of the total carbon storage, with a carbon density of 25.49 t/hm². Bamboo forest has the highest carbon density (35.75 t/hm²).(2) Among different dominant tree species, Populus spp. occupies the highest proportion, and its carbon storage accounts for 56.90% of the total. The carbon storage of arbor forests is dominated by young and middle-aged stands, with the order from high to low: middle-aged forests > young forests > near-mature forests > mature forests > over-mature forests. Carbon density shows a trend of increasing with stand age.(3) In terms of different origins, the carbon storage of planted forests is much higher than that of natural secondary forests. Planted forests account for 96.41% of the total carbon storage, reaching 3.127 06×10⁷ t.(4) The order of carbon density among different forest types is: timber forests > protective forests > special-purpose forests > non-timber forests, and the order of carbon storage was consistent with this. Timber forests account for 66.50%.(5) From the perspective of the ecosystem, the total carbon storage of the forest ecosystem is 2.080 4×10⁸ t. The order of spatial distribution of carbon storage in the forest ecosystem is: soil layer > arbor layer > shrub layer > herb layer > litter layer. The carbon storage of the soil layer is 1.588 8×10⁸ t, accounting for 76.37% of the total forest ecosystem carbon storage, followed by the arbor layer(16.16%).【Conclusion】Jiangsu Province demonstrates a substantial growth trend in its forest carbon sequestration. The ratio of aboveground forest carbon storage to underground soil carbon storage is approximately 3∶7. Compared to the national average, the forest carbon density in Jiangsu Province is relatively low, with planted forests as the main type, an excessively high proportion of Populus spp. area, and young and middle-aged stands as dominant forest types. The results provide a data reference for improving the carbon sequestration capacity per unit area of forests, which is conducive to the protection and sustainable development of forest resources—especially the protection of understory shrubs, herbs, and litter layers to increase soil carbon storage and to construct a reasonable forest management model.