半干旱农牧交错区小城镇发展及其对土地利用时空格局的影响分析

Impacts of Town Development on Tempo-spatial Landuse Pattern in Semi-arid Agro-pastoral Transitional Area

本文以半干旱农牧交错区不同地貌类型上三个典型小城镇为例,定量分析了1977-1987-1998年来小城镇的发展及其对周边土地利用格局变化的影响,结果表明,三个类型区小城镇的变化均经历了无序增长到有序增长的过程,这种变化过程间接地反映了人口的密集程度。采用3个指数(斑块百分比、最大斑块指数和平均斑块大小)对典型区域土地利用类型随其与小城镇的距离变化的分析结果表明,在梁滩相间的合同庙乡,研究区内其余土地类型间的时空变化趋于相对稳定,变化主要发生在灌木和农地之间,人类影响强度与距离间呈较强的负相关;在覆沙(黄土)丘陵区布连乡,随着距离的增加,3个指数典型年份基本上呈现不同程度的“高-低-高”的趋势,前一个峰值更多地反映人类活动的影响,而第二个峰值的出现则可能与布连乡南部的河流分布有关。在位于毛乌素沙地北缘的新街镇,随着距离的增加,3个年份的3个指数的变化无显著的规律,这可能与该区域内牧民居住的分散性有关,或与城镇本身变化的无序性有一定的关系,自然条件可能更多的影响着土地利用时空格局的变化,可见以城镇为中心的人类活动对土地利用格局的影响很大程度上受到自然条件的限制。本研究为我们准确地把握不同类型区土地利用格局的变化规律并据此建立土地变化的预测模型提供了科学的理论依据。

This research, taking 3 typical towns of Yijin Holo County, Inner Mongolia, as study sit.es, quantified the town development and＇its impacts results showed that the areas of 3 on tempo -spatial landuse pattern during 1977 - typical towns increased from disorderly to orderly density indirectly. The landuse type change based on the distance from towns, using e. percentage of landscape （ PLAND）, largest patch index （LPI） and average patch 1987 - 1998. The research which reflected population three landscape indices, i. size （APS）, indicated that in mosaic area of ridgeland and floodland, change occurred mainly in shrubland and farmland, showing negative correlation between human influence and distance from town; in sand - or loess - covered hilly area, the change of 3 indices is ＂high -low -high＂, the first peak reflect human influence more, and the second peak might relate to rivers in the southern part of this area; In Mu Us Sandland area, there was no regular change for 3 indices following distance change, which might relate to spotted settlement sites or disorder of this town change. It is very obvious the impacts of human activities around towns on landuse pattern were limited to the extent by physical conditions. This study are helpful to better understand landuse change and to establish landuse simulation models.