基于景观生态和马尔可夫过程的西安地区土地利用变化分析

LUCC Analysis of Xi'an Region based on Landscape Ecology and Markov Model

本文利用三期TM影像,通过遥感与GIS技术,结合景观生态学理论和马尔可夫过程,深入分析了15年来西安地区土地利用变化的数量和空间特征以及由此所引起的一系列生态环境效应,主要表现在:城镇建设用地、果园与未利用地面积显著增加,农用地和水体面积呈减少趋势,城镇建设用地的增加是以侵占大量农田为代价的。景观破碎度变大,形状趋于复杂,优势度降低,多样性和均匀性增大,景观类型有向多样性或均衡化方向发展的趋势。景观的匀质化发展降低了景观抗干扰的能力,同时导致景观稳定性降低。为了弥补传统上由各类土地总面积的变化来解释变迁的缺点,研究利用马尔可夫过程对研究区的土地利用变化进行理论趋势值分析,分析表明研究区内土地利用变化以各类型转化为城镇建设用地的趋势最强,在一定程度上显示了研究区内正处于城市化的快速阶段。

Based on TM images （path 127, row 036） acquired on August 1988, October 1998 and May, 2003 respectively, six types of land use were classified using Maximum Likelihood Method with the support of Remote Sensing and GIS. Using the theory of landscape ecology analysis and Markov model, we made quantitative analysis of the quantity and spatial feature changes of land use in Xi＇ an region during the period of 1988 to 2003, and a series of ecology environmental effects. Land use change/cover in Xi＇an region can be listed as follows： urban construction land, orchard and uncultivated land increased sharply, while water-body, arable land and forestland decreased apparently; arable land and water-body are more fragmentary and interspersed than ever before; the increase of the area of urban construction land was at the cost of encroaching a wealth of arable land. In general, the landscape features were retrieved using the software of Fragstats： the number of patches increased a lot and it was more than twice the number of what it was in 1988. The landscape become more and more fragmentized and the shape of the landscape become more complex. The predominance index decreased, too. The Shannon diversity index increased from 1.0789 to 1. 2425, while the Shannon evenness index increased from 0.6021 to 0.6935. It indicates that the landscape is getting more and more diversified and balanced, but poor to withstand the interference. It also indicates that human activities might disturb the landscape more and more seriously. In order to make up the deficiency of traditional explanations on land use changes through use of land area change of its kind, we analyzed the land use change and its theoretical development in Xi＇an region on the basis of Markov model. The results suggest that the trend that all the other land types translated into the construction land appears much more dominantly than any others in the studying region. In the meantime, the result also shows that the Xi＇ an city is in a fast developing stage of urbanization to a certain extent. Land use/land cover change is a complex system, which is affected by many comprehensive factors, including socio-economic and natural and environmental factors. Using the Markov model as a basic tool to predicate land use/land cover may not well indicate the real facts and it still needs other methodology to improve the model in order to make it more approach the fact.