Study On The Geographical Distribution Patterns And Potential Suitable Areas Of Three Reaumuria Species

Climate is the key factor that determines geographical distribution of vegetation type and species.There are more and more researches on predicting the influence of climate on species distribution and the relationship between them attention attracting attentions.The researches on global warming have shown that arid and semi-arid areas are the most obvious warming areas in recent decades.Due to the increasing of desertification in China and the long-term grazing of herbivores,the desert vegetation has been seriously endangered.Reaumuria plants are highly drought-tolerant shrubs worthy of attention in arid and semi-arid areas of China,which are also one of the main shrub species for conservation and cultivation of forage shrub forests and degraded grassland with strong drought resistance,salt tolerance,sediment collection ability and great ecological plasticity,and they play an important role in maintaining the balance of ecosystem in desert areas.In order to research the geographical distribution of the three species of Reaumuria plants in northwest China and its relationship with climate and analyze the classification of suitable regions of the three species of Reaumuria plants,the influence of environmental variables on the three species of Reaumuria plants and their cross-region analysis,the geographical distribution data of the three species of Reaumuria plants was obtained in this paper through China Digital Herbarium,published papers in China and abroad and Chinese Flora and other materials.The distribution data of Reaumuria soongarica,Reaumuria trigyna and Reaumuria kaschgarica was analyzed as the main ingredient combined with the original distribution points and the current climate indexes.The geo-information system(ArcGIS)technology and maximum entropy(MaxEnt)model software was used to simulate the potential suitable areas of three species of Reaumuria plants in three periods,and the environmental variables that mainly affected Reaumuria plants in the potential suitable areas were analyzed,then cross region analysis was carried out on the potential suitable area distribution map obtained.The results showed that:1)The northernmost of R.soongarica was on the way from Balba to Burjin in Altai Mountain region of Xinjiang(47.91°N),the southernmost was near Gaolan County,Gansu Province(36.15°N),and the difference between the maximum north-south latitude was11.76°.The easternmost was in the southeast of Erlianhaote(112.2°E),the westernmost was in Ucha County(75.1°E),and the difference between the maximum east-west longitude was37.1°.The northernmost position of R.kaschgarica was Kaktoru Mountain in Ahqi County,Xinjiang(41.33°N),the southernmost was Gouli Township in Dulan County,Haixi Prefecture,Qinghai Province(35.66°N),and the difference between the maximum north-south latitude was 5.67°.The easternmost was the north of Yunjiakou,Xining City,Qinghai Province(101.85°E),and the westernmost was Yutian County,Hetian District,Xinjiang(81.5°E),and the difference between the maximum east-west longitude was 20.35°.The northernmost of R.trigyna was Xilingol League Abaga Banner of Inner Mongolia Autonomous Region(44.98°N),the southernmost was Linxia County,Gansu Province(35.48°N),and the difference between the maximum north-south latitude was 9.5°,the easternmost was Saihan District,Hohhot City,Inner Mongolia Autonomous Region(112.72°E),the westernmost was Linxia County,Gansu Province(102.99°E),and the difference between the maximum east-west longitude was 9.73°.2)According to principal component analysis,the original geographical distribution points of the three species of Reaumuria plants are analyzed with the current climate index.In general,the geographical distribution of the three species of Reaumuria plants is different from that of the current climate index,but for the three species of Reaumuria,temperature is the most important factor,mainly the highest temperature,average temperature,average maximum temperature.In addition,the light factors also have certain influence on R.trigyna and R.kaschgarica,mainly sunshine hours,monthly sunshine percentage.3)Potential suitable areas of the R.kaschgarica are mainly in Qinghai,southern Xinjiang and parts of Gansu;the potential suitable areas of R.trigyna are mainly concentrated in Ningxia,Inner Mongolia,Gansu and parts of Xinjiang and Qinghai.The potential suitable areas of R.soongarica are scattered in northern Xinjiang and some southern regions,northwest Qinghai,most of Gansu and Inner Mongolia.The potential suitable areas of R.kaschgarica and R.trigyna are increasing.The potential suitable area of R.soongarica changes greatly,and the potential suitable area will decrease in large area and shrink westward in the future period,so the change is obvious.In general,the high suitable area of the three species of Reaumuria plants has been reduced greatly,and the more suitable area and the lower suitable area have obvious shrinkage phenomenon.4)Three species of Reaumuria plants in the historical period,the current period and the future period of the cross-region mainly concentrated in the central Qinghai and the southern region of Xinjiang and Gansu.The total cross region of the three species of Reaumuria plants increased with the change of the period.For the potential suitable areas in the future,the area of cross area between R.soongarica and R.kaschgarica between two Reaumuria plants is1104767.51km~2.312010.91km~2 is the minimum cross area between the R.kaschgarica and the R.trigyna.The cross area of the potential distribution area in the future of the three species is 259490.13 km~2.5)By using the maximum entropy model,the environmental variables that mainly affect the three species of Reaumuria plants in the potential suitable area are analyzed.The key environmental variables of the potential distribution of R.trigyna and R.soongarica are mean temperature,hottest season rainfall,wetest monthly precipitation,warmest quarter precipitation and wetest quarter precipitation,etc.The key environmental variables affecting the potential distribution of R.kaschgarica are altitude,isothermal and seasonal temperature changes.In general,the three Reaumuria plants have a great correlation with temperature,which is consistent with the results of principal component analysis.6)AUC values of R.trigyna and R.kaschgarica calculated by MaxEnt model are greater than 0.9,and the AUC values of R.soongarica are greater than 0.850,which indicates that the prediction accuracy of MaxEnt model is high,which can be used to predict the potential suitable distribution areas of three species of Reaumuria plants.