玛河流域景观生态风险评价与时空分异

Landscape Ecological Risk Assessment and Its Spatio-temporalVariations in Manas River Basin

以玛纳斯河流域作为研究区,结合特殊的干旱区山地-绿洲-荒漠系统(Mountain-Oasis-Desert System简称MODS),综合考虑遥感影像数据光谱信息和纹理特征,将研究区分为耕地、林地、草地、水体、裸地、居民地、工业用地和冰川/永久积雪等8个景观类型,利用FRAGSTATS软件计算景观指数,引入生态风险的指数,将研究区划为低、较低、中、较高、高生态风险区五级,评估其景观格局的生态风险时空变化特征。结果表明:1)1990—2015年间,玛纳斯河流域景观变化主要表现为耕地、建设用地的增加以及水体、冰川/永久积雪面积的缩减;2)玛纳斯河流域的景观生态风险等级空间分布具有明显的差异,较低风险区的面积变化较为明显,低、较低生态的风险区比重有所上升,除此以外,林、草地类型各生态风险的等级所占比重的起伏波动具有明显的差异。建议应当合理地利用土地资源,尽量保护林地、草地等景观脆弱行较低的原生景观类型,禁止为开垦耕地而破坏林地、草地;增加土地的利用效率,更要对高等、较高生态风险区加强监管。

The typical region of the Manas River Basin was chosen as study area.Images in 1990,20,2010,and 2015 were obtained in the study area.On the basis of the special Mountain-Oasis-Desert System,by comprehensively considering the spectral information and textural features of the remote sensing images,landscape was classified into eight types,including cultivated land,forest land,grassland,water body,bare land,residential land,industrial land,and ice.Ecological risk index and landscape indices were mostly calculated and interpolated for the whole region by FRAGSTATS,which was always divided into five different risk zones:extremely low,low,moderate,high,and extremely high,in order to assess the spatio-temporal changes in ecological risk for every landscape pattern.The results showed that:(1)From 1990 to 2015,river landscape change in Manas mainly are the increase of cultivated land and construction land and the areal reduction of forest,glacier(permanent snow)cover area;(2)The manas river basin ecological risk level spatial distribution difference is obvious,high ecological risk area of change is significant;(3)The proportion low and the lower ecological risk areas are rising,the proportion of level of ecological risk of forest and grassland types varies and fluctuates significantly.We should reasonably use land resources,try to protect forest land,meadow with lower landscape fragile degrees of primary landscape types,prohibit land reclamation and destruction of forest land and meadow.It is recommended to improve the efficiency of land utilization and strengthen the supervision on higher ecological risk area.