陕北黄土高原典型人类活动影响下景观生态风险评价

Landscape Ecological Risk Assessment Under the Influence of Typical Human Activities in Loess Plateau,Northern Shaanxi

植被恢复促进了景观格局和生态过程的改变,景观生态风险评价有助于揭示人类干预下生态系统结构、功能等在景观尺度产生的潜在不利生态效应。以生态脆弱、人与生态环境的相互作用敏感的陕北黄土高原为典型研究对象,根据2000、2005、2010和2015年夜间遥感地图、植被净初级生产力和土地利用数据,建立景观生态风险指数,对陕北黄土高原的综合风险状况及其变化进行定量评价,并对植被变化、城镇化分别与景观生态风险变化间的相关关系展开分析。结果表明,景观格局变化对生态稳定性有潜在影响,景观生态风险以增长趋势为主,2005—2010年景观生态风险增长的范围最大,涨幅为186.0%,其中,中风险和极高风险等级面积增长超2.7倍;2010—2015年景观生态风险增加有所缓解,增加12.9%;2000—2005年景观生态风险降低26.0%。景观生态风险低等级面积逐渐缩小,其他等级面积逐渐变大。其中,2005年后景观生态风险等级呈片状扩展,主要位于陕北西北部风沙区。植被变化、城镇化分别与景观生态风险值变化之间在西北风沙滩区均呈显著正相关。在景观生态风险增加区植被呈退化趋势;在景观生态风险低值区即退耕还林逐年拓展的区域,植被恢复促进景观生态风险的降低。植被恢复对景观生态风险的影响大于城镇化进程。研究成果对于区域发展和生态恢复的综合调控具有一定参考价值。

Vegetation recovery promotes changes to landscape patterns and ecological processes.Ecological risk assessments of landscape can help reveal the landscape-scale,potentially harmful ecological effects produced by ecosystem structure and function under human intervention.Due to the weak ecosystem and sensitive interaction between humans and the ecological environment,the Loess Plateau in Northern Shaanxi,China,is targeted as the study object.According to night remote sensing photomaps,vegetation net primary productivity(NPP),and land use data for 2000,2005,2010,and 2015,risk indexes of landscape ecology are established to quantitatively assess the status and variations of comprehensive risk to the Loess Plateau in Northern Shaanxi and to analyze the correlations of landscape ecological risk with vegetation change and urbanization.As a result,the change of the landscape pattern produces potential effects on ecological stability.The fastest landscape ecological risk area expansion was increased by 186.0%during 2005-2010.The areas of middle and extremely high risk levels had been increased over 2.7 times.The percentage of expansion was slowed down to 12.9%during 2010-2015.The eco-risk levels during 2000-2005 was shrunken by 26.0%.The area with low risk is reduced,whereas the areas with other levels of risks were increased.After 2005,the levels of landscape ecological risks extended in the shape of a flake and were mainly located in the sandy area of northwest of Northern Shaanxi.Vegetation change and urbanization are positively correlated with landscape ecological risk variation in the sandy area in the northwest.In the area with increased risk,the vegetation displayed a trend of degradation.In the area with low risk,that is,in the extended area of the Grain-to-Green Project(GTGP),vegetation recovery promotes the reduction of ecological risk.Compared with urbanization,vegetation recovery has larger effects on landscape ecological risk.The results have certain reference value for the comprehensive regulation of regional development and ecological recovery.