森林死亡及其对气候变化响应研究进展

Research on Forest Mortality and its Response to Climate Change

森林生态系统是人类生存繁衍和可持续发展不可缺少的组成部分。森林死亡是森林衰退的主要表现形式之一。近年来全球升温导致全球范围内尤其半干旱区极端气候频发,造成大面积森林死亡,对植物群落、生态功能、生态系统服务等产生重要影响。不同地区不同类型的森林死亡呈现出不同的时空格局及驱动机制。研究森林死亡时空动态及其对气候变化的响应对改善生态环境、促进森林生态恢复具有十分重要的意义。基于样地网络实地调查与遥感分析是进行森林死亡动态监测的主要手段。本研究对森林死亡的定义、生态影响和监测方法以及气候变化与森林死亡之间的关系等研究进行了系统的总结,结果发现未来需加强以下几个方面的研究:第一,深入分析干旱胁迫的时空特征,厘清干旱的季节性特征和融雪时间的变化等,并加强生物群系之间及其与气候变化之间关系的研究和控制实验的研究,以揭示干旱和升温对森林死亡的作用机制。第二,研究干旱胁迫下树木的碳储存与利用机制以及生态水文过程等现象,深入探讨两者的耦合机理,并增加对大气CO_2、氮沉降、臭氧和干旱动态变化以及植物生产力、树液流动、菌根作用等的分析,构建和完善基于过程的树木死亡机理模型,以便能更准确地预测未来森林死亡事件的发生。第三,加强国际合作,构建全球范围内的数据体系,为大尺度上的森林死亡及其对气候变化的响应研究提供数据和技术支持。

Forest ecosystem is extremely important for human sustainability.Forest mortality is the main form of forest decline.As global temperature rises in recent years,climate anomalies occur frequently all over the world,particularly in semi-arid region,resulting in a large area of frequent forest mortality.Forest mortality has significant impacts on plant communities,ecological functions and ecosystem services.Different types of forest mortality in different regions show different spatio-temporal patterns and driving mechanism.Studies of spatio-temporal dynamics of forest mortality and the response to climate changes are meaningful to improve ecological environment and promote the restoration of forest ecosystem.Fieldwork based on plot network and remote sensing analysis are the primary means of dynamic monitoring of forest mortality.This paper systemically summarized domestic and international related studies of the definitions,ecological consequences and monitory measures of forest death and its responses to climate changes.Results indicated that the following aspects will be considered in the future studies.Firstly,in order to analyze the influence mechanism of climate changes on forest death,the spatio-temporal characteristics of drought should be explored deeply to clarify its seasonal dynamics and the temporal change of snow melting.The relationships among biomes and their relationships to climate changes as well as the related control experiments should also be strengthened.Secondly,in order to predict the occurrence of future forest mortality more accurately,emphases should be put on carbon storage and utilization mechanisms and ecological and eco-hydrological processe of trees and their coupling effects.Studies on atmospheric carbon dioxide,nitrogen deposition,the dynamic changes of drought,plant productivity,sap flows and mycorrhizal effect should also be investigated to build underground growth model and improve forest mortality model.Thirdly,international corporation should be enhanced to build worldwide data system and provide data and technical support for studies on large scale forest mortality and its response on climate changes.