Abstract:

The exploration of the evolution characteristics and driving forces of habitat quality based on land use changes is of great importance for protecting the biodiversity in arid areas and promoting its ecosystem health. In this thesis, the Manas river basin, a typical watershed in the northwest arid area, was taken as an example. According to the 8 periods of land use data, meteorological station data and DEM data from 1980 to 2020, the habitat quality module of the InVEST model was used to quantitatively study the temporal and spatial variation law and complex driving factors of habitat quality in arid area. The results indicated that (1) the unused land and grassland were the main land use types in the Manas river basin, accounting for 41.49% and 28.54% of the study area respectively. (2) Some basic characteristics of land use changes in the study area included the constant expansion of the cultivated land that occupied grassland and unused land, as well as the large-scale melting of snow glaciers leading to bare rocks and grasslands. (3) From 1980 to 2020, the habitat quality of the Manas river basin first showed improvement followed by continuous deterioration, and the average habitat quality decreased by 0.059. (4) In terms of the significant differences in the spatial distribution of habitat quality, the overall performance showed the following pattern: low mountain area>high mountain area>oasis area>desert area. The habitat quality grade was comparatively lower, accounting for more than 40.36% of the study area. (5) The continuous occupation of grassland and unused land by the expansion of cultivated land, the large-scale melting of snow and glaciers and the degradation of grassland with medium or high coverage were the main reasons for the deterioration of habitat quality in Manas river basin, in which the expansion of cultivated land and encroachment on grassland led to a substantial decline in the quality of oasis habitats. The main reasons for the improvement of habitat quality in desert area were the expansion of oasis encroaching on desert and the increase of grassland area with low coverage in the ecotone of desert and oasis. The mutual transformation between medium- and low-coverage grasslands caused by climate change determined the change of habitat quality in low mountainous areas. The primary reasons for the deterioration of habitat quality in alpine areas were the melting of snow and glaciers and the degradation of grassland with high or medium coverage. Therefore, future land use in arid areas should follow the principle of “moderate pursuit” and adopt strategies tailored according to local conditions. In addition, attention should be given to major ecological restoration and protection projects to facilitate the protection of ecosystems such as grasslands, wetlands, woodlands, and alpine glaciers.

Key words: arid areas, Manas river basin, land use, InVEST model, habitat quality, biodiversity

摘要：

基于土地利用变化探讨干旱区流域生境质量的演变特征及驱动力,对保护干旱区生物多样性、促进生态系统健康具有重要意义。以西北旱区典型流域--玛纳斯河流域为例,基于1980-2020年8期土地利用数据、气象站点数据和DEM数据,借助InVEST模型生境质量模块,定量研究了干旱区流域生境质量的时空变化规律及其复杂驱动因素。结果表明,（1）未利用地和草地是玛纳斯河流域主要的土地利用类型,分别占研究区面积的41.49%和28.54%。（2）耕地持续扩张并侵占草地与未利用地,积雪冰川大面积消融转为裸岩和草地是研究区土地利用变化的基本特征。（3）1980-2020年期间,玛纳斯河流域生境质量呈先改善后持续恶化的趋势,生境质量均值减小了0.059。（4）生境质量空间分布差异显著,整体表现为低山区>高山区>绿洲区>荒漠区,生境质量等级以较低为主,占研究区面积的40.36%以上。（5）耕地扩张不断侵占草地和未利用地、积雪冰川大面积融化以及中、高覆盖度草地退化是玛纳斯河流域生境质量恶化的主要原因。其中耕地扩张侵占草地导致绿洲生境质量大幅度下降。绿洲扩展侵占荒漠以及荒漠-绿洲交错带低覆盖度草地面积的增加是荒漠区生境质量改善主要原因。低山区生境质量变化取决于气候变化导致的中、低覆盖度草地之间的相互转化。积雪冰川融化以及高、中覆盖度草地退化是高山区生境质量恶化的首要原因。因此,今后干旱区应坚持适度追求和因地制宜原则,积极响应和开展重大生态恢复及保护工程建设,加强对草地、湿地、林地、高山冰川等生态系统的保护。

关键词: 干旱区, 玛纳斯河流域, 土地利用, InVEST模型, 生境质量, 生物多样性