岷江上游林农边界效应对植被生物量的影响

边界效应是当前生态学领域的研究热点之一,但对于生物量的边界效应关注很少。生态系统尺度上的边界效应研究,多采用野外样线法获取数据。以岷江上游林农边界为例,对生物量的边界效应进行了分析。通过在野外布设样线获取边界上的生物量数据,同时应用地理信息系统从遥感影像中提取边界上的植被NDVI,运用地面调查数据对NDVI值进行验证的结果表明,用NDVI来反映植被生物量具有可信性。对两种数据进行初步统计分析,并应用移动窗口法对生物量的边界效应进行了定量判定,研究结果表明:1)在林农边界上,林地边缘的生物量低于林地内部的生物量,边界效应范围为60/m到65/m,农田边缘的生物量高于农田内部,边界效应范围为60/m到90/m;2)基于野外数据和基于NDVI的边界效应判定结果基本一致,用NDVI作为生物量的指标进行边界效应分析是可行的;3)在分析生物量的边界效应时,研究范围取200~300 m较为合适,研究粒度取30 m较10 m效果更佳。

The Influence of Edge Effect on Vegetation Biomass of Forest-farmland Boundary in the Upper Min River

Edge effect is one of the hotspots in ecological research,while the edge effect of biomass is rarely analyzed.Most studies at ecosystem scale get data from field transect inventory.This paper analyzed the edge effect of biomass at the forest-farmland boundary in the upper Min River.The information of vegetation on landscape boundaries was derived from field investigation and Landsat TM satellite images.The correlativity between biomass and NDVI showed the latter can be used as biomass.Then the NDVI was analyzed as well as biomass was done,and Moving Split-windows Analysis was used to quantitatively determine the range of edge effect.The results were as following: 1) On forest-farmland boundary,biomass of forest edge was lower than that of forest interior,with edge effect depth ranged from 60m to 65 m,while biomass of farmland was higher than that of farmland interior,with edge effect depth ranged from 60 m to 90 m.2) Edge effect depth of biomass detected from field data had comparable result with that based on NDVI.Therefore,NDVI is reliable in analyzing edge effect on biomass.3) As for study scale,a range of 200 m to 300 m is enough and applicable,and a grid of 30 m is better than 10 m.