Vegetation landscape pattern change and characteristics of spatial distribution in south edge of Mu Us Sandy Land
Vegetation landscape pattern change and characteristics of spatial distribution in south edge of Mu Us Sandy Land
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DOI：
10.5846/stxb201208251201
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发表时间：
2013
影响因子：
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通讯作者：
周淑琴 Zhou Shuqin;荆耀栋 Jing Yaodong;张青峰 Zhang Qingfeng;吴发启 Wu Faqi
中科院分区：
文献类型：
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作者：
周淑琴 Zhou Shuqin;荆耀栋 Jing Yaodong;张青峰 Zhang Qingfeng;吴发启 Wu Faqi
毛乌素沙地南缘属于鄂尔多斯高原和黄土高原交错带，同时又是典型的农牧交错带，生态环境极为脆弱。植被作为生态系统的初级生产者，不仅为生态系统提供系统所需的有机物质和生物化学能，还能改善和调节生态系统中的环境。植被变化是荒漠化发生或逆转最直观的表现，也是气候和人为因素对生态环境影响的敏感指标。定边县植被格局信息可作为植被保护、恢复和重建的依据。遥感数据包括1991年、1999年和2007年的TM或ETM+影像。根据不同的地形将1991-207年的植被覆盖信息划分为两个区域。利用计算的两个区域的景观指数分析植被格局的变化。结果表明：(1)16年间，两个区域的植被覆盖的转折点是1991年。植被覆盖状况在第一阶段持续恶化，在第二阶段均有所改善。同时，低水平和低水平占绝对优势。从1991年到1999年，两个带的水平都在上升，沙区从55%上升到70%，丘陵地区从70%上升到80%，5%以下的高水平比率继续下降。2007年，两个地区的优势度都变成了低和中等水平。沙区有55%，(2)1999年后植被景观格局变化趋势相同，但变化程度不同。景观多样性和景观均匀度呈先减小后增大的交替分布类型。沙区景观破碎化指数呈先增大后减小的趋势，丘陵区景观破碎度呈持续上升趋势。从整体上看，沙区景观破碎度小，多样性高。植被交替分布明显，均匀度指数高。丘陵区景观格局特征相反，外部干扰较强，沙区景观破碎度小，多样性高。植被格局在演化过程中为多核型，同时核心区的大小、形状和类型都有不同程度的变化，沙区核心区多为非植被斑块，丘陵区植被覆盖度较高的斑块，核心区周围植被分布呈梯度分布。
The south edge of Mu Us sandy land belongs to the Erdos Plateau and the Loess Plateau transition zone.At the same time the area is the typical farming-pastoral region and the ecological environment is extremely fragile.Vegetation as the primary producers of ecological system not only provides the system required organic substances and biological chemical energy,but also can improve and adjust the environment in the ecological systems.Vegetation change is the most intuitive performance of desertification development or reversal.It also is the sensitive index of the climate and human factors impacting on the ecological environment.Vegetation pattern information of Dingbian County can be served as vegetation protection,restoration and reconstruction. Remote-sensing data includes the TM or ETM+ images of 1991,1999 and 2007 in this study.Vegetation coverage information extracted from 1991 to 207 by using RS and GIS is divided into two areas according to different landform.Landscape indexes of two zones calculated are used to analysis vegetation pattern changes.The results show the following conclusions.(1)The turning point of vegetation coverage is 1991 in two zones during sixteen years.Vegetation coverage conditions continue to worsen in the first stage while both improve in the second stage.The lower and low level accounted for the absolute superiority.Meanwhile,both levels in two zones is increasing from 1991 to 1999.It has risen from 55% to 70% in sandy areas and from 70% to 80% in hilly region.The high level ratio below 5% is continuing to decline.In two zones dominance level are changed to low and moderate level in 2007.They are 55% in sandy area,70% in hilly region.The high level has risen with different degree.(2)After 1999 the vegetation landscape pattern changes reversed.Landscape pattern change trend is the same but the degree is different.Landscape diversity and landscape evenness firstly decreases and then increases.Types of alternating distribution firstly wake and then enhances.The landscape fragmentation index of sandy areas firstly increases and then decreases,while continuously rising in hilly region.On the whole sandy areas landscape fragment degree is small and diversity is high.Vegetation alternating distribution is obvious and evenness index is high.The characteristic of landscape pattern is on the contrary in hilly region.The interference from outside is strong in sandy area,but weak in hilly region.(3)Vegetation pattern is the multi-core model during evolvement process.Meanwhile,the core size,shape and type change in different degrees.Sandy area core mostly is non-vegetation patches while hilly area high vegetation coverage level patches.Vegetation around the core distribution shows a gradient.