岷江上游景观边界网络格局分析

格局与过程是景观生态学研究的核心内容,与基于斑块的研究相比,基于边界的研究是格局与过程研究的一个新的切入点.以岷江上游地区为例,基于TM影像数据,应用RS、GIS、Fragstats等软件,选用边界长度、边界密度、边界海拔、结点数量、网眼大小、网络连接度等指数,研究了景观边界网络格局的变化,并分析了与之相关的生态过程.结果表明,在1974～2000年期间,由于人为干扰强度的加剧,岷江上游景观边界网络结构变得更加复杂,在早期以边界长度增加为主,网络连接度变大,在后期以边界数量和结点数量增加为主,网络连接度变小;森林景观与低坡位景观类型间的边界减少,森林下线上移;农田与林地的边界在早期增加,1986年后减少,而与灌木林地的边界持续增加;随着林地的蚀退,森林结构变得简单化,而农田、灌木林地、草地等景观类型的结构变得更加复杂.

The pattern analysis of landscape boundary network in the upper reaches of Minjiang River

Spatial pattern and processes are two most important aspects of landscape ecological study. Compared with patch-based studies, boundary-based studies provide new perspectives in understanding landscape processes. We analyzed data from TM image, forest stand map, land use map and field investigation using GIS, RS,and Fragstats software. With an example from the upper reaches of Minjiang River, we analyzed landscape boundary network pattern change and the related ecological processes. The main results are: From 1974 to 2000, human disturbance made the structure of landscape boundary network in this area more complex than the prior period, with increased boundary length and network connectivity at the beginning, and decreased landscape network connectivity at the later stage. This is because the rates of boundary number and node number increases are faster than that of the boundary length. The boundary length between forest and other landscape types at lower slope positions decreased, indicating that forest boundaries at lower elevations moved upwards. Before 1986, farmland-forest boundaries increased and after 1986 they decreased, whereas farmland-shrub boundaries increased during the period. The shrinkage of forest area resulted in simpler forest landscape pattern and more complex spatial patterns of shrub, grassland and farmland landscapes.