长白山森林破碎化程度及其对净初级生产力影响关系研究

Impact of forest fragmentation on net primary production in Changbai Mountain

在许多热带地区的森林破碎化对森林碳储量能够产生负面影响,但其对温带森林生态系统的固碳服务一直有争议。天然林保护工程实施以来,对于森林破碎化以及对净初级生产力的影响仍需探讨。研究利用遥感影像对长白山地区进行土地分类并量化景观指数以分析森林破碎化程度,基于CASA方法模型反演计算1985年、1995年、2005年和2015年的净初级生产力动态,分析不同管理措施下长白山国家级自然保护区和7个林业局的森林破碎化程度及净初级生产力值。研究结果显示:从1985年到2015年在长白山地区主要森林类型的总面积呈增长趋势,其森林初级生产力也同样表现增长趋势;对于常绿针叶林植被类型,初级生产力与森林破碎度的相关性在长白山保护区外部呈较强的负相关关系;对于针阔混交林植被类型,人类活动为主要原因所导致的森林破碎化对净初级生产力变化具有关键作用,且影响逐渐减弱。森林景观斑块边缘的碳损失情况量化结果表明,净初级生产力随边缘深度的增加而增长,在保护区内部的斑块加权平均净初级生产力约为保护区外部区域的4倍。研究揭示了植被净初级生产力对森林破碎化和管理措施的敏感度,为深化森林生态系统服务的驱动研究提供了依据。

Forest fragmentation can exert a negative impact on forest carbon storage in many tropical areas,but its influence on temperate forest ecosystems is debatable.The influence of the Natural Forest Protection Program(NFPP)on forest fragmentation and further impacts on Net Primary Productivity(NPP)is still unclear.We quantified forest fragmentation in terms of landscape indices based on remote sensing landcover maps.Over the past 30 years,NPP dynamics(1985,1995,2005,and 2015)have been evaluated based on the Carnegie-Ames-Stanford approach(CASA).We compared forest fragmentation and NPP in the Changbai Mountain National Nature Reserve(CMNR)and adjacent forestry bureaus to highlight the differences in the NFPP management measures.The results show that the total forest areas of the main forest types in Changbai Mountain increased from 1985 to 2015,and the NPP of the main forest types exhibited increasing trends.For the evergreen needle leaf forest,the correlation between NPP and forest fragmentation was deep outside CMNR;the forest fragmentation led to a negative impact on NPP.For the mixed forest,fragmentation was because human activities played a key role in the NPP and the impact was weakened over 30 years.By quantifying the carbon loss at the edge of forest landscape patches,we found that an increase in the distance from the edge promoted the growth of NPP,and the weighted-average NPP for the landscape patch in CMNR was approximately four times that of outside CMNR.This research highlighted the fragmented patches of the sensitivity of NPP and forest management and provided some significance for predicting the impact of forest fragmentation on temperate forest ecosystem functions.