甘肃白龙江流域景观生态风险评价及其时空分异

以我国典型生态环境过渡带——甘肃白龙江流域为对象,借助GIS技术和Fragstats软件,基于土地利用变化的生境脆弱度和景观生态损失度构建了流域景观生态综合生态风险评价模型,并利用空间自相关分析方法,开展了土地利用变化及其生态风险评价与时空分异研究.结果表明:1990~2010年白龙江流域土地利用变化明显,林地和建设用地呈现增长趋势,耕地和草地面积呈现减少,未利用地和水域则呈波动变化.研究区景观生态风险空间分布差异明显,白龙江流域西北部和北部的生态风险高于流域的西部、东部和南部.同时,各风险等级上呈现“两头小中间大”的趋势,即中等风险区面积呈扩张的态势,低风险区和高风险区呈减弱的趋势.流域景观生态风险具有显著的空间集聚特征,其生态风险值呈现显著的空间正相关关系,这可能是流域生态风险时空分布与土地利用强度、土地利用结构及人类活动之间关系密切.

Landscape ecological risk assessment and its spatiotemporal variation of the Bailongjiang watershed,Gansu

To reveal the impact of landscape ecological risk (LER) of land use change and its spatiotemporal variation at the watershed scale, Bailongjiang watershed, a typical transitional ecotone between Loess Plateau and Tibetan Plateau, was chosen as the study area. Based on the data integration analysis platforms of GIS technology and Fragstats 3.3, the assessment method of land use LER was constructed with the incorporation of the environmental vulnerability degree and landscape ecological loss degree. Spatial distribution of landscape ecological risks of land use change in the study area was analyzed by means of spatial autocorrelation. The results showed that: the land use changed obviously from 1990 to 2010 in the watershed. The area of forest land and built-up land increased gradually while the cultivated land and grassland decreased. Unused land and water cover area were fluctuated during the research period. There was some obvious spatial difference of LER levels in the watershed. The LER level of the area in the northern and northwestern of Bailongjiang watershed was higher than that of the area located in the western, southern and eastern mountainous area of the watershed. Furthermore, the moderate LER area increased remarkably while the low-risk area and high-risk area both decreased. The agglomeration features of the LER were obvious and value of LER charactered as notable positive spatial correlation. The change of LER might be closely related with human activity, land use intensity and structure.