Appropriate Distribution And Diversity Of Ephemeral Plants In Early Spring In Junggar Desert

The geographical distribution pattern of a species is an intuitive representation of its suitability for the environment.At present,we can analyze and predict the appropriate factors and distribution patterns of plants in a certain period of time by the distribution range of plants in a certain area,the size of the distribution intensity and the number of plant species.This study not only provides guidance and reference for the scientific research of ecological and economic important species in ecology and phytogeography,but also has great significance and ecological value for the study of the geographical distribution pattern of short-lived plants in desert areas,such as sand surface fixation and vegetation restoration in extreme environments.The Junggar Desert is located in northern Xinjiang,with Gurbantunggut Desert as the center.It belongs to the extreme environment area of Xinjiang.This area is arid,hot and has a large evaporation capacity,which is not conducive to the survival of most plants,but it is the only distribution area of short-lived plants in early spring in China.Ephemeral plants in early spring are of great ecological and economic value to local development.In this study,some typical annual early spring ephemeral plants and perennial early spring ephemeral plants in the Junggar Desert were selected as research objects to explore the appropriate distribution pattern,species diversity pattern and change trend of typical plants in the Junggar Desert under the baseline period and future climate,and to explore the driving factors of spatial distribution pattern.In this study,the typical early spring short-lived plants in the Junggar Desert were selected as research objects.A total of 713 effective distribution sites were collected by searching numerous specimen sharing platforms,related books and research literature.A total of 39 species of annual early spring short-lived plants covering 10 families,11 species of perennial short-lived plants covering 4 families,a total of 50 typical plants.The environmental factors were screened in R language,and Biomod2 was used to construct a composite model to simulate the appropriate distribution pattern,change trend and environmental driving factors of each family,ephemeral plant group and ephemeral plant group in the baseline period and future period(2061-2080,SSPs245 medium emission scenario).At the same time,we explored the diversity patterns of ephemeral and ephemeral plants and their change trends.The main conclusions are as follows:(1)The AUC value and TSS value were all higher than 0.8 and TSS value was higher than 0.7 in each family model.The combined model was more accurate and could be used for simulation studie(2)The simulation results of the current and future suitable distribution of 10 families of annual early spring ephemeral plants showed that the suitable distribution of 10 families of typical ephemeral plants in the baseline climate environment had certain similarities.The distribution pattern of desert marginalization showed that the southern margin of Junggar Desert was the main suitable habitat area,and there were a few suitable habitat areas in the northern end of the desert and the nearby fringe areas.In the future period,except for some plants,the overall expansion trend to the high latitude area.In the baseline period,most of the typical plants distributed in the southern margin of Junggar Desert and had a higher overlap with oasis cities in the southern margin of the desert.The suitable areas of papaveraceae,Caracinaceae and Ranunculaceae were small,without lamellar suitable areas,and scattered in the southern edge of desert.The majority of chenopodium,legumes,comhinaceae,Compositae and cruciferae plants are located in the southern edge of the desert,and there are a few suitable areas in the western or northern edge of the desert.Cruciferae,Compositae,and Levofloxacin were widely suitable for distribution,including a large flake area,and they were all located in the southern desert margin.Levofloxacin and graminea have a suitable range not only in the southern margin of desert,but also in the middle of desert.Graminea is more middle,while Levofloxacin is relatively eastern.The suitable range of cruciferae,comfrey and legumes was obvious in the northern end of the desert,which mainly included Altay City and northern Fuhai County in Altay region.In future climate,the suitable area of cruciferae,Compresaceae,Compositae,Ophiaceae,Chenopodiaceae,Levofloxacin,Levofloxacin and Ranunculaceae generally showed signs of expansion,while the suitable area of leguminous and graminea showed a trend of expansion.In future climate,the suitable area of cruciferae,Compresaceae,Compositae,Ophiaceae,Chenopodiaceae,Levofloxacin,Levofloxacin and Ranunculaceae generally showed signs of expansion,while the suitable area of leguminous and graminea showed a trend of expansion.The three typical plants of the Fabaceae all showed a decreasing trend of suitable growth ratio.The proportion of Eremopyrum orientale and Eremopyrum distans decreased,the proportion of Bromus tectorum remained unchanged,and the proportion of Schismus arabicus increased slightly.Desert marginalization characteristics of the suitable areas of Ranunculaceae and Ranunculaceae were significant.In terms of the migration of centroid,the future pattern centroid migration mainly includes the migration direction toward northeast,due north and southwest,and the migration of the short-lived group to and near the desert center.(3)The simulation results of the current and future suitable distribution of the four families of perennial ephemeral plants showed that the overall distribution pattern of the four families of ephemeral plants was relatively similar.The southern margin of the Junggar desert was the main suitable distribution area,followed by the northwestern and northern edge of the desert,but the eastern and eastern margins were less suitable distribution.In the future period,the overall expansion trend to high latitude areas will be presented.The suitable distribution area of Dianthus and Lycoraceae was small,mainly distributed in the southern margin of Junggar desert.The whole caryophyllaceae is mostly dotted distribution,lycoraceae is relatively clustered,can be connected into lines.The suitable areas of umbelliferae and Liliaceae are relatively extensive,with a certain lamellar suitable area outside the southern edge of the desert,and a certain suitable range in the southwest of the desert.In the future period,the suitable areas of other typical short-lived plants showed an expansion trend,except for the slight reduction of the suitable areas in umbelliferae.Most of the suitable areas of Lycoris were suitable habitats.Next,Liliaceae extended outward from the southwest margin to the northeast margin,and a certain area of suitable area was added to the north end of the desert.The distribution pattern of desert marginalization except southeast corner of Caryophyllidae and umbelliferae was obvious in the southern oasis urban belt and the northern desert end of Altay City and Fuhai County.In terms of the migration of centroid,the future pattern centroid migration mainly includes the direction of northeast and northwest migration,and the centroid migration of the short-lived group to and near the desert center.(4)The results of species richness calculation by point pattern and species distribution model were consistent.The results of point pattern were scattered and fragmented,while the results of species distribution model had strong continuity.The species richness of ephemeral plant groups and ephemeral-like plant groups showed an uneven pattern of high in the south and low in the north under the baseline and future periods.The species richness of the ephemeral plant groups was mainly distributed in the southern margin of Junggar Desert,the rest were mostly distributed in the desert marginalization,and the desert center was less distributed and fragmented.The high species richness areas were concentrated in the oasis urban belt in the southern margin.Compared with the two groups,the distribution of the ephemeral plant group was more uniform in the east-west direction,and the distribution of the ephemeral plant group was more inclined to the Midwest and southwest.The ephemeral plant group was higher in the south and lower in the north,and the distribution trend of the ephemeral plant group was higher in the west and lower in the east.The desert ephemeral plants and similar ephemeral plants were mainly distributed in and around oasis cities in the southern edge of the desert,including Wushi,Fukang,Changji,Wujiaqu,Hutubi,Manas,Shawan,Shihezi,Kuitun,Wusu and Karamay.In the future,the species richness values of plants in the two groups generally increased,and showed a trend of expanding to the high latitude areas.In addition to the southern edge of the desert,the northern end of the desert areas with high species richness values were newly added,mainly including Altay City and Fuhai County.(5)Combined with the contribution ranking of species distribution models and the analysis of future climate fluctuations,we concluded that the driving factors affecting the appropriate distribution of typical annual early spring ephemeral plants and typical perennial early spring ephemeral plants in the Junggar Desert were the same,but the importance ranking was different,indicating human activities,habitat heterogeneity,and hydrothermal conditions.The transient plants were human activities,habitat heterogeneity and hydrothermal conditions,and the influence of water factor was greater than that of temperature factor.For short-lived plants,habitat heterogeneity,human activities,and hydrothermal conditions,the influence of temperature factor was greater than that of water factor.