基于土地利用变化的玛纳斯河流域景观生态风险评价

摘要：随着人类活动范围日益扩张和强度增加，景观生态风险评价已经成为预测和衡量生态环境质量和动态演化的重要手段。本文以玛纳斯河流域（简称玛河流域）为研究区，选取2000、2005、2010和2015年4期Landsat TM/ETM遥感影像，运用ENVI软件对研究区土地利用类型进行解译，定量分析流域近15年来土地利用动态变化特征，基于景观格局指数，采用地统计学方法，探究玛河流域景观生态风险程度及时空分异特征。结果表明：（1）2000—2015年，玛河流域景观格局发生了较大变化，耕地景观面积增加最多（2638.31 km^2），主要由草地和未利用地转入；未利用地景观面积减少最多（2559.99 km^2），主要转化成了草地、耕地和林地；（2）将流域景观生态风险划分为5个等级，研究期内流域低、中风险区面积增加而较高、高风险区面积减少，整体景观生态风险指数减小，所以研究区生态环境在整体上呈现好转；（3）2000—2005年、2010—2015年玛河流域在景观风险分布格局上发生较小变化，但2005—2010年流域景观风险分布格局发生较大变化，主要是中、较高和高风险区向流域南北方向分散并转移，低风险区向流域北部转移。

Landscape ecological risk assessment in Manas River Basin based on land use change

With the increasing scope and intensity of human activities, landscape ecological risk assessment has become an important means to predict and measure the quality and dynamic evolution of ecological environment. Taking Manas River Basin as the study area and selecting Landsat TM/ETM remote sensing images from 2000, 2005, 2010, and 2015, this paper used ENVI software to interpret the land use types and quantitatively analyzed the land use dynamic variation characteristics of the basin from 2000 to 2015. Based on the landscape pattern index, and the geo-statistical methods were used to explore the degree of landscape ecological risk and the characteristics of the spatial-temporal differentiation of the Manas River Basin. The results showed that: (1) From 2000 to 2015, the landscape pattern of the Manas River Basin has taken great changes. The area of cultivated land has increased the most (2638.31 km²), which mainly transformed from grassland and unutilized land. While the area of unutilized land has decreased the most (2559.99 km²), which mainly transformed into grassland, cultivated land and forest land. (2) The landscape ecological risk of the basin was divided into five grades. Within the period of this study, the regions with the lowest and medium levels of ecological risk have increased, whereas the regions with the higher and highest levels of ecological risk have decreased, and the whole landscape ecological risk index decreased. Thus, the ecological environment of the study area showed a trend of improvement on the whole. (3) The landscape risk distribution pattern of the Manas River Basin changed slightly during 2000-2005 and 2010-2015, but it changed significantly during 2005-2010. The main changes in the medium, higher and highest levels of ecological risk have dispersed and transferred to north and south of the study area, and the lowest level of ecological risk have transferred from south to north of the study area.