Changes Of Geographical Distribution Of Alpine Vegetation Under The Cliamte Change In Southwest China

Revealing the response of natural ecosystems in the context of climate change is a hot topic in geography,ecology,and environmental science.Alpine vegetation growing in extremely harsh climates and extremely poor soil conditions is most sensitive to climate change and can capture early signals of the effects of global climate change.Southwest China is rich in biodiversity and is an important ecological barrier area in China.The alpine vegetation area accounts for one third of the total area of alpine vegetation in China.It is particularly important to study its response to future climate change.which is of great significance to how to maintain the level of regional ecological security while developing economy.Based on the MaxEnt model,this study verified the model simulation accuracy by using the data of alpine vegetation and ecological climate data in Southwest China,and analyzed the contribution rate of every climatic factors.Then ArcGIS was used to analyze the changes of the geographic distribution of the climatic suitability of alpine vegetation in different periods from 1980 to 1999,from 2000 to 2018 and from 2020 to2040,and the distance and direction of gravity center migration of geographical distribution were discussed.The main research conclusions are as follows:(1)The average temperature in the southwestern region from 1980 to 2018 showed a significant upward trend,with an average rate of 0.29 ? /10 a.Winter temperature(January)> The average temperature> Summer temperature(July);The trend of precipitation change is not significant.The temperature(precipitation)is spatially distributed in the east high(more)west low(less),south high(more)north low(less).With the increase of altitude,the increase in temperature in most areas of high mountains and extremely high mountains is greater than that in middle and low mountains,but the trend of precipitation change is more complicated than temperature.(2)The main climatic factors affecting the geographical distribution of alpine vegetation in the southwest are Summer temperature?Winter temperature?Summerprecipitation and Annual precipitation,with a cumulative contribution rate exceeding80%,of which the Summer temperature has the highest contribution rate(Up to 33%),the effect of temperature on the growth of alpine vegetation in the southwest is significantly higher than that of precipitation.(3)The spatial distribution of climatic suitability for the geographical distribution of alpine vegetation is basically the same in different periods.Moderate and highly suitable areas are mainly distributed in Hengduan Mountains,southern Tibet and western Qinghai,of which highly suitable areas are mainly distributed between4900-5300 m above sea level and the rest are unsuitable areas.With climate change,the proportion of suitable areas decreased and that of unsuitable areas increased from 1980 to 2040.Among them,the highly suitable area has a decreasing trend at altitudes<4900m and >5600m,and has an increasing trend at altitudes 4900-5600 m.(4)The geographical distribution center of alpine vegetation in different periods is basically distributed at the junction of Qinghai and Tibet(Golmud City,Ando County and Nierong County);From 2000 to 2018,the center of gravity moved to the northwest with a migration distance of 2.3km;From 2020 to 2040,the center of gravity will migrate southeast under most climate change scenarios,with a maximum migration distance of 10.9km and a minimum migration distance of 5.5km.