黄土高原小流域景观多样性动态分析

以纸坊沟为例，在地理信息系统支持下获得计算景观多样性的有关参数，运用斑块大小及数量、平均分维数、多样性指数、优势度、均匀度、破碎度和聚集度等指标，对黄土高原小流域40年来景观多样性动态变化进行了分析．结果表明，40年来，在以人类活动干预和植被内源演替为主要驱动力的共同作用下，该流域斑块总数增加，旱地基质逐渐被林地、草地等其它景观基质所取代，景观格局趋于破碎，景观类型多样性和均匀度增加，且后20年景观多样性的变化幅度远远大于前20年的变化幅度．目前流域已经由1958年以旱地为基质的高度均质化的景观生态系统转化为与当地地带性景观相适应的以草地和林地为基质的高度异质化的景观生态系统，生态系统结构、功能已具有较强的稳定性．

Analysis of the landscape diversity dynamics of small watershed in the Loess Plateau

Taking Zhifanggou Gully as the study area, some landscape diversity indexes were attained under the support of GIS technology. Utilizing the indexes such as patch size, average fractal dimension, diversity index, dominance, evenness, fragmentation and conglomeration, the changes of landscape diversity in the small watershed in Loess Plateau during the past 40 years were studied. The landscape diversities had been increasing for the recent 40 years due to the effect of both human activity and plants' endogenesis succession. The patches number increased, and the dryland matrix was substituted gradually by other matrixes such as meadow and woodland. The landscape pattern trended to be fragmentized and the indexes of landscape type diversity and evenness increased, while landscape diversities changed greater during 1978-1998 than during 1958-1978. Homogeneous dryland matrix landscape ecosystem in 1958 had already changed into heterogeneous meadow and woodland matrix landscape ecosystem, which had greater structure stability and stronger function than before.