近三十年来四合木分布区景观格局变化及其对生态安全的影响

Change of Landscape Pattern and Its Impact on Ecological Environment Security in the Distribution Region of Tetraena mongolica Maxim.During the Last 30 years

以1977年MSS及1990,2000,2005年TM影像数据为基本信息源,运用3S技术及景观格局分析软件,对四合木分布区的景观构成和景观格局特征进行动态分析,探讨了景观格局变化对区域生态安全的影响.结果表明:近30年来,四合木分布区景观构成变化较大,其中四合木种群面积不断减少,耕地、城镇、工矿等人工景观类型不断增加,沙地与其他植被面积扩展明显;研究区景观多样性增强,优势度降低,景观格局趋于破碎并向异质化发展.这必然会导致景观稳定性及其抗干扰能力下降,产生土地退化、环境污染、生物多样性降低等区域生态安全问题,因此,应加强四合木及其生境保护,控制景观格局变化,以保障区域生态安全.

Using the technology of remote sensing ,geographical information system, global positioning system and the analysis software of landscape pattern, the paper analyzed 4 sensing images of Tetraena mongolica distribution region in different periods （1977,1990,2000, 2005） are analyzed. The results are used to study the dynamic changes of landscape composing and landscape patterns and to discuss its impact on ecological environment security. The results show that the landscape composing in the distribution region of T. rnongolica has been changed largely and the population area of T. rnongolica has been decreasing while the farming land, town and industry land, desertifieation land and else vegetations increased largely. On landscape scale, Shannon＇ s diversity index was increased, while Dominance index decreased year after year. It indicated the landscape pattern tend to be fragmented and poly-basic in the distribution region of T. rnongolica. It must be result in landscape stability and anti-interference capability decreasing, bringing about region ecological environment security questions such as land degradation, environment pollution, biodiversity decreasing. It is a fundamental method to enforce the protection of T. mongolica and its habitat and to control the change of landscape pattern.