Study On Ecosystem Stability Changes And Climate Impacts In Qilian Mountain National Park

Stability is an important characteristic that determines the survival or decline of ecosystems,and it is also the basis for ecosystems to provide sustained services.Resistance and resilience are two important aspects of ecosystem stability,and they are the main content of research on ecosystem stability.The Qilian Mountains National Park has complex and diverse climates,various ecosystem types,and significant spatial differentiation.It is an important ecological security barrier,water conservation area,and biodiversity protection area in China.Global climate change has had a wide and profound impact on vegetation,becoming the main driving force behind significant changes in vegetation in arid areas,seriously affecting the overall stability of vegetation.Based on the two basic connotations of ecosystem stability（resistance stability and resilience stability）,this study uses a comprehensive measurement model of vegetation sensitivity index（VSI）and landscape pattern dynamic analysis method to explore the spatiotemporal changes in the stability of the main ecosystems in the Qilian Mountains National Park from 2000-2020,and quantify the main climate factors affecting their stability.The main conclusions of the study are as follows:（1）Over the past 21 years,the annual average temperature,precipitation,and radiation in Qilian Mountains National Park have shown an increasing trend,with increases of 1.14℃/10a,45.2 mm/10a,and 101.57 MJ·m^-2/10a,respectively.The Enhanced Vegetation Index（EVI）shows a northwest-southeast distribution pattern,with a vegetation increase of 0.009/10a.The area with increased vegetation cover in the park accounts for 97.14%,and the overall trend of greening is strong and positive.As the altitude increases in the park,the temperature continues to decrease,and the precipitation fluctuates in an increasing-decreasing-increasing trend,with the EVI increasing to a peak of 0.224 and then decreasing continuously to almost 0 above an altitude of 3000 meters.（2）In Qilian Mountain National Park,the area of basic resistance stability accounted for 88.39%,among which the strong resistance stability and relatively strong resistance stability account for 15.72%and 34.32%of the total area,respectively.The degree of ecological resistance stability shows obvious spatial heterogeneity,not only in terms of the longitude differences in stability among different types of ecosystems,the resistance stability of grassland and forest ecosystems gradually increases from east to west,while that of shrub and desert ecosystems gradually weakens;More importantly,it is manifested as differences in the stability gradient along the altitude,below 2800 meters,except for some forest areas,it is mostly desert grassland and mountain desert with overall weaker resistance stability;Between 2800-4700 meters,there are forest grassland,subalpine shrub meadow,and alpine meadow with higher vegetation coverage and relatively rich species diversity,and overall stronger resistance stability.Above 4700 meters is high mountain desert,permafrost glacier and multi-year accumulated snow,where the vegetation has strong resistance to cold,frost,and drought.（3）In Qilian Mountain National Park,the area of basic resilience stability accounted for 87.23%,of which 29.74%showed strong resilience stability,and19.75%showed relatively strong resilience stability.In general,the ecosystems in the western part of the park have higher resilience than those in the eastern part.The longitude difference in resilience stability is manifested as follows:grassland,forest,and desert ecosystems gradually become more resilient from east to west,while the shrub ecosystem gradually becomes weaker.The altitudinal gradient changes are shown as follows:as the altitude increases below 2600 m,the resilience stability of the ecosystems gradually decreases;and in the interval between 2600-3700 m,the resilience stability remains at a low level.Above 3700 m,the resilience stability of the ecosystems gradually increases with altitude.（4）The main controlling climate factors in different spatial locations of the same ecosystem are diversified.The stability of grassland ecosystem in the western section of the park is mainly affected by precipitation,while in the central section it is affected by both precipitation and temperature,and in the eastern section it is mainly affected by both temperature and radiation.The stability of forest ecosystem is mainly affected by the combined effect of temperature and precipitation changes.The stability of shrub ecosystem is mainly affected by the joint influence of radiation and temperature changes.The stability of desert ecosystem in the western section of the park is mainly affected by precipitation,while in the central and eastern sections it is affected by both temperature and radiation.（5）Based on the coupling intensity between ecosystem stability and climate,Qilian Mountain National Park can be divided into general areas of vegetation sensitivity and key areas of vegetation sensitivity.The former has strong stability of resistance and resilience and weak sensitivity to climate.It is mainly distributed in the eastern section of the park and needs regular monitoring and maintenance to ensure its stability.The latter has weak resistance and resilience,and is more sensitive to climate change,mainly distributed in the western and central parts of the park.More closely related measures,such as vegetation restoration and ecological restoration,can be taken to protect the ecological environment of these areas.