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疏伐是森林经营管理中经常用到的重要营林措施。疏伐不仅可以提高森林的木材产量,而且还对森林生态系统的碳储量及其碳储量变化产生重要影响。本文采用森林生态系统碳收支模型CBM-CFS3模拟了13种不同的疏伐情景对落叶松林生态系统碳储量及其变化影响。模拟结果显示,与未疏伐林分相比,疏伐能大大降低落叶松林生态系统生物量碳密度。模拟时间尺度内,不同设定疏伐情景下平均生物量碳态密度的最小值和最大值分别是30.3 tC ha~(-1)和47.8 tC ha~(-1),相差达58%。同未疏伐林分相比,所有疏伐林分的死亡有机物碳密度(包含土壤碳密度)均呈增加的趋势,与生物量碳密度的减少趋势相对。然而,由于死亡有机物碳的增加不足以弥补生物量碳的损失,落叶松林生态系统碳密度会因疏伐而降低。因此,强度的疏伐会使落叶松林生态系统由碳汇转变成碳源。由于此模型未考虑疏伐产生的木材本身的碳汇以及木材产品的碳替代所产生的碳汇作用,如替代碳排放强度较大的钢材、铝、水泥、PVC等作为建筑材料,未来的研究应考虑这部分碳汇。
Thinning is an important management measure commonly used in forest management. Thinning can not only increase timber production in forests, but also have a significant impact on the carbon stocks of forest ecosystems and their carbon stock changes. In this paper, we use the CBM-CFS3 model to simulate the impacts of 13 different thinning scenarios on the carbon storage and its changes in the ecosystem of larch forests. The simulation results showed that thinning could significantly reduce biomass density of Larix gmelinii forest ecosystems compared with no thinning stand. Under the simulation time scale, the minimum and maximum values of average biomass carbon density under different thinning scenarios are 30.3 tC ha -1 and 47.8 tC ha -1, respectively, with a difference of 58%. Compared with the no-thinning stand, the organic carbon density (including the soil carbon density) of all the thinning stands showed an increasing trend, which was opposite to the decreasing trend of the biomass carbon density. However, due to insufficient increase of dead organics carbon to make up for the loss of biomass carbon, the carbon density of larch forest ecosystems will be reduced due to thinning. Therefore, the intensity of thinning will make larch forest ecosystem from carbon sink into carbon source. Since this model does not consider the carbon sequestration of wood itself generated by thinning and the carbon sink produced by carbon substitution of wood products, such as replacing steel with higher carbon emission intensity, aluminum, cement and PVC as building materials, future research This part of the carbon sink should be considered.