1985年~2000年西藏地区景观格局变化及影响因子分析

利用西藏地区1985年及2000年两期遥感影像解译的数据,并结合GIS和统计软件,对西藏地区15年来景观格局变化特征进行分析。结果表明:1985年~2000年,西藏地区各景观要素之间发生了显著的变化,未利用地、居住地及建筑用地、灌木林地及疏林地面积增加,其中居住地及建筑用地增加的速度最快,增长率为46.6%;农用地、森林、草地、河流及湖泊、冰雪地面积减少,河流、湖泊和农用地面积减少率较大,分别为13.1%和10.4%;各景观要素发生相互转移,其中转移程度较大的是草地与未利用地,未利用地向草地转换了80313.46km2,草地向未利用地转换了155974.97km2,占草地转出量的90%以上。通过对景观格局分析发现,总体景观斑块数量增加,最大斑块指数减小,景观多样性指数、均匀度、破碎度增加,优势度等减小,西藏景观格局向多样化、破碎化发展;同时各景观要素之间聚集度指数在增加,形状指数、分维数减小,景观不同要素分布交错格局趋于简单,斑块形状向着规则化方向发展。利用典型相关性分析方法对景观格局变化的影响因子进行分析,发现人口增长、过牧等人为活动以及海拔、气温等自然因子是西藏景观格局变化的主要影响因子。

The Analysis of the Landscape Pattern and Impact Factors in the Tibet Region Between 1985 and 2000

Based on the maps interpreted from remote sensing image of 1985 and 2000,as well as combining with GIS and the software of mathematical statistics,the characteristics of dynamic changes of landscape pattern were analyzed in the past 15 years in this paper.The results were as follows: from 1985 to 2000,The landscape pattern elements of the Tibet occurred a noticeable change,there was a increase in unused land,construction land,shrub land area increased increased by 46.6%;it was decreased in agriculture land,forest land,grass land,water area;Meanwhile,river & lake,agriculture land area decreased bigger,had decreased by 13.1% and by 10.4%;The conversions between grass land and unused land were drastic comparatively,the conversions area was 80313.46 km2 from unused land to grass land,and the conversions area was 155974.97km2 from grass land to unused land,the grass land from the unused land account for 90% of the all conversions;The analysis of the landscape pattern indicated that the number of patches increased continuously,meanwhile,the largest area of patch decreased,and the degree of diversity,equality and fragmentation of landscape increased,and the degree of dominance decreased.The landscape pattern developed towards fragmentation and diversity.The spatial connectivity among landscape elements increased,and the shape index and the fractal dimension index decreased.The distribution of different landscape elements changed simpleness,the shape index of patch developed towards regularization.The canonical correlations analysis found the main impact factors were acute human activity such as population increase and overfeed livestock as well as nature factors such as altitude and temperature.