造林再造林、森林采伐、气候变化、CO2浓度升高、火灾和虫害对森林固碳能力的影响

森林生态系统具有吸收大气CO_2、缓解气候变化的作用。造林再造林作为京都议定书认可的大气CO_2减排途径,是提高森林固碳能力的低成本、有效策略。森林生态系统固碳能力还受森林采伐、气候变化、大气CO_2浓度升高、火灾以及虫害等自然因素和人为因素的强烈影响。综述了全球和区域造林再造林的固碳能力,以及目前较受重视的一些因素(森林采伐、气候变化、大气CO_2浓度升高、火灾以及虫害)对森林生态系统固碳能力的影响。结果表明,全球造林再造林固碳能力为148—2400TgC/a;采伐造成的全球森林碳损失最大为900 TgC/a,其次是火灾为300 TgC/a,虫害造成森林碳释放最小在2—107 TgC/a之间。建议在今后的研究中,应关注固碳措施和多种环境因素对森林生态系统固碳能力,尤其是对森林土壤固碳能力的影响,严格控制森林采伐和火灾发生,以及减少或避免造林再造林活动引起的碳泄漏。

Influence of afforestation, reforestation, forest logging, climate change, CO2 concentration rise, fire, and insects on the carbon sequestration capacity of the forest ecosystem

Controlling the rising levels of atmospheric greenhouse gas (GHG, especially CO₂) concentration to mitigate global climate change is arguably the most challenging environmental issue encountered by China and many other countries. Forest ecosystem, which is an integral part of terrestrial ecosystems, can play a significant role in absorbing CO₂ from the atmosphere and aiding global climate change mitigation, subsequently contributing to meet the national commitment and demand of carbon emission reduction and carbon sink enhancement. Afforestation and reforestation, as recognized in the Kyoto Protocol, provide relatively low-cost and effective solutions to enhance forest ecosystem carbon sink. Meanwhile, the carbon sequestration capacity of a forest ecosystem is enormously affected by various natural and anthropogenic factors, which may convert the forest ecosystem from a carbon sink to a source. Therefore, the understanding of the influence of afforestation, reforestation, and those factors on the carbon sequestration capacity of the forest ecosystem is important for the accurate estimation of global and regional forest ecosystem carbon budget. In this study, the recent research progresses on the effect of afforestation and reforestation on carbon sequestration capacity of global and regional forest has been reviewed, along with the influence of several natural and anthropogenic disturbances (i.e., forest logging, climate change, CO₂ concentration enhancement, fire, and insect). It was indicated that the carbon sequestration capacity of global afforestation and reforestation was in the range of 148 to 2400 TgC/a, varying regionally as follows: tropical forest (1700 TgC/a) > boreal forest (700 TgC/a) > temperate forest (27-500 TgC/a). Furthermore, besides climate change and CO₂ concentration rise, other factors that caused carbon emissions in the forest have been summed up and listed below. Forest logging caused the highest carbon emissions (900 TgC/a), followed by forest fire (300 TgC/a), and insects caused the lowest carbon emissions (2-107 TgC/a). Henceforth, more attention should be paid on the influence of carbon sequestration measures and integrated effects of multiple forms of disturbance on the carbon sequestration capacity of forest ecosystems, especially carbon sequestration capacity of forest soil. Furthermore, controlling forest logging and fire, along with reducing or avoiding additional carbon leakage due to afforestation and reforestation would also greatly contribute to forest carbon sequestration.