森林采伐对闽北天然次生林碳储量及其动态的影响

Impact of harvesting intensity of the natural secondary forestry on the carbon stocks reduction in northern Fujian

科学合理地计量采伐对森林碳储量的保护有重要的现实意义,已引起了越来越多的关注。在对闽北天然次生林择伐与更新研究基地进行长期监测的基础上,结合伐木制品的碳储量及碳排放过程,综合分析了不同强度采伐对生态系统碳库的影响。结果表明,仅从乔木层生物量池看,弱度择伐后10 a碳储量已经超过伐前,中度择伐要15 a才能恢复,采伐强度越高,恢复所需要的年限越长。若考虑伐木制品的碳储量,则中度择伐需要10 a才能恢复到伐前,强度和极强度择伐需要15 a才能恢复,皆伐恢复较为困难,15 a后的碳储量仅为伐前的42.98%。从碳汇角度出发,闽北天然次生林宜采用中度以下的择伐。

In this paper, we prefer to bring about our study rcsuhs on the impact of harvesting intensity of natural secondary forestry on the carbon stocks reduction in northern Fujian. As a matter of fact, it has become a more and more public concern to overcutting of our forests, which contributes to the global terrestrial carbon sink, though the changes in the carbon sequestration in response to the varied for estharvesting intensities have still being debated. The statistical recordings tell us that forests were harvested at different intensities （low intensity of 13.0 % in volume, medium intensity of 29.1% , high intensity of 45.8%, overhigh intensity of 67.1%, clear cutting of 100% ）. Data on the production of timber products and emission from decomposition were also used to estimate the carbon stocks in timber products and landfills. The results of our study show that, the tree layer pool being taken into account, the biomass carbon stocks of the low intensity cutting tends to increase by 7.82 % during 10 years after operation, and it is expected to increase by 16.52% during 15 years after operation,which implies that it would take less than 10 years for the low intensity cutting to recover. But for the medium intensity cut ting it would take 15 years to recover. The greater intensity of cut ting, the longer time for the carbon stocks to recover. When consider ing the influence of harvested timber products on the carbon stocks, it can properly said that the medium intensity cutting can get recovered 10 years later,whereas it would take 15 years to get it recovered for overhigh intensity cutting. Thus, it is difficult for the clear cutting to recover,for it is only less than half of the original carbon storage to get restored 15 years later through overcutting. However, low inten sity cutting is expected to be the greatest favor for ecosystem carbon sequestration, followed by medium intensity cutting. With the in crease of harvesting intensity, the deterioration in ecosystem carbon stocks would naturally follow. Therefore, it is recommended to take selective cutting operation, especially low intensity and medium inten sity cutting, so as to prevent the carbon stocks from being sunk from the forest management perspective. Thus, the results of our research is expected to provide a reference for the forest management.