土地利用变化对青海湖流域生境质量的影响

Evaluation on the Impact of Land Use Change on Habitat Quality in Qinghai Lake Basin

以青海湖流域2005-2015年土地利用图为基础,利用InVEST模型和"3S"技术对青海湖流域生境质量进行定量估算,分析了青海湖流域生境质量的时空分布特征,以揭示土地利用变化对流域生境质量的影响。结果表明,(1)草地、湖泊、高寒荒漠、裸岩石质地、沼泽是青海湖流域主要的土地利用类型,占流域总面积的90%左右。2005-2015年,流域内各土地利用类型基本保持稳定,但主要土地利用类型均发生不同程度的变化,湖泊、交通工矿建设用地、永久性冰川雪地面积比例分别增加了0.22%、0.03%和0.03%;沼泽、滩涂、沙地、高寒荒漠分别减少了0.13%、0.04%、0.04%和0.03%。(2)青海湖流域生境质量表现为东南高、西北低。2005、2010、2015年三期生境质量第1等级与第2等级占流域总面积的53.73%-72.56%。三期生境质量第4等级与第5等级占流域总面积的23.32%-29.57%。2005-2015年,流域生境质量整体稳步趋好,局部有所降低。(3)2005-2010年,流域内草地、沼泽面积下降,居民点、交通建设用地沙地、面积增加,河流、裸土、居民点生境质量分别下降了0.09、0.04和0.02。耕地面积减少,威胁源强度降低,耕地生境质量升高了0.02。2010-2015年,河流面积略有增加,河流生境质量升高了0.11。青海湖面积增加了63.70km^2,湖泊生境质量升高了0.06,同期湖泊生境质量第1等级面积占青海湖面积的97.13%,占生境质量第1等级面积的57.65%,占流域面积的14.57%。青海湖水体面积及生境质量可作为流域生态环境质量的重要指示因子。(4)青海湖流域生境质量呈现西北冷环湖热的特点,热点区域主要位于青海湖北部和南部,冷点主要分布于流域西北部。2005-2015年,流域西北部冷热点面积的波动与裸岩石质地、高寒荒漠面积变化密切相关。青海湖北部草地面积减少、居民点及交通工矿建设用地面积增加导致热点面积下降。流域土地利用变化是导致生态环境质量变化的重要原因。

Based on the land use map of Qinghai Lake basin from 2005 to 2015, this paper used the InVEST model and "3 S" technology to quantitatively analyze the spatial and temporal distribution characteristics of habitat quality and reveal the impact of land use change on habitat quality in the basin. The results showed that,(1) Grassland, lake, alpine desert, gravel desert and wetland were the main types of land use in Qinghai Lake basin, accounting for about 90% of the total area of the basin. From 2005 to 2015, the land use types in the basin remained basically stable, but the main types of land use changed in varying degrees. The total area of lake, construction land, and permanent snow/glacier increased by 0.22%, 0.03% and 0.03%, while the area of wetland, tidal flat, sandy land, and alpine desert decreased by 0.13%, 0.04%, 0.04%, and 0.03%, respectively.(2) The habitat quality of the Qinghai Lake basin was high in the southeast and low in the northwest. Habitat quality level 1 and 2 across the three stages(2005, 2010, 2015) accounted for 53.73%-72.56% of the total basin area. Habitat quality level 4 and 5 accounted for 23.32%-29.57% of the total basin area. From 2005 to 2015, the overall quality of the habitat in the basin had steadily improved and partially reduced.(3) From 2005 to 2010, the area of grassland and wetland in the basin decreased, and the area of settlement, construction land and sandy land increased. The habitat quality indices of rivers, bare soils and settlements decreased by 0.09, 0.04 and 0.02, respectively. The area of farmland decreased, the intensity of threat sources decreased, and the quality of farmland habitat increased by 0.02. From 2010 to 2015, the river area increased slightly, and the river habitat quality increased by 0.11. The area of Qinghai Lake increased by 63.70 km^2, and the quality of lake habitat increased by 0.06. In the same period, the area of lake habitat quality level 1 taking up 97.13% of the area of the Qinghai Lake, accounted for 57.65% of the total area of habitat quality level 1, taking up 14.57% of the total area of the basin. The water body area and habitat quality of Qinghai Lake could be used as the important indicators of the ecological environment quality of the basin. And(4) the habitat quality of the Qinghai Lake basin was characterized by the hot spots of the northwestern region and the cold spots of the surrounding lake. The hotspots were mainly located in the north and south of Qinghai Lake, and the cold spots were mainly distributed in the northwest of the basin. From 2005 to 2015, the area fluctuation of cold and hot spots in the northwestern part of the basin was closely related to the changes in gravel desert and alpine desert area. The reduction of grassland area in the northern part of Qinghai Lake, and the increase in the settlement areas and construction land areas have led to a decline in the area of hotspots. Land use change in the basin plays an important role in determining the quality of the ecological environment.