Effects Of Climate Change On Distribution Of Dominant Species And Pattern Of Vegetation In Qilian Mountains

Alpine areas are sensitive to climate change.Objectives in the study are to understand the changes of climatic biological factors,to clarify the impacts of climate change on species and vegetation patterns in Qilian Mountains,and to accurately simulate spatial distribution of dominant species.Results are conducive to understand the response of dominant species to global climate change in Qilian Mountains,in turn,contribute to develop strategies for adapting the climate warming.Qilian Mountain ecosystem is an important part of maintaining ecological security,and also the basis of maintaining ecological balance and economic development in Hexi Corridor.Global change characterized by climate warming is taking place.However,the research on the impact of climate change on the ecosystem of Qilian Mountains is not comprehensive,and the contribution of key climatic factors to the distribution of dominant species and vegetation patterns in the Qilian Mountains is also poorly understood.In order to clarify the impact of climate change on the spatial distribution of dominant species and vegetation pattern in Qilian Mountains,this study used multiple variable analysis methods to obtain the characteristics of climate change in Qilian Mountains.The applicability of various niche models in Qilian Mountains was compared.Differences of different atmospheric models in simulating the spatial distribution of species were analyzed.Based on the selected optimal niche model and the integrated atmosphere model,this study simulate the potential distribution of five species under different climate scenarios.Suitable areas for each species were divided according to its potential distribution.Finally,the potential impacts of climate change on vegetation pattern in Qilian Mountains were discussed.The main conclusions are as follows:(1)The Qilian Mountains are sensitive to global warming.In 1957-2017 years,the increase rate of the average temperature was 0.32°C/10 years,and the rate was higher than that in national and global scale.Under different scenarios in the future,the temperature will increase by 125.1%-286.4%,and the precipitation will increase by 7.7%-14.4%.(2)Compared with the other nine niche models,Maxent is the optimal model for species distribution in the study area,which can effectively predict 66.7% to 96.6% of the actual area of five species.(3)Different GCM outputs have great differences,which result in the difference of the simulated suitable area for five species(the error range from 11.7% to 46.0%).The error range of suitable area by the same atmospheric model is 3.6%-93.6%,indicating the difference of different atmospheric models has greater impact on the results than that of different scenarios of the same model.(4)Five factors(bio5,aspect,bio10,bio1 and bio7)do more contribution to the distribution of Picea crassifolia,Sabina przewalskii,Potentilla fruticosa,Caragana jubata and Rhododendron capitatum,respectively.Species requirement of the niche range in climatic and geographical variables is different,which is the main reason for species distribution difference.(5)Climate change leads to changes in the suitable area of each species.Comparing with the present suitable area,the change rates of suitable areas under different scenarios for Picea crassifolia,Sabina przewalskii,Potentilla fruticosa,Caragana jubata and Rhododendron capitatum are from-1.81% to 0.41%,from-5.02% to 12.96%,from 1.32% to 2.08%,from-5.05% to 5.56% and from-0.02% to 4.30%,respectively.Climate change has led to a large area shifts among different suitable grades of species.Under different scenarios,the area of conversion accounts for a large proportion of the suitable area of each species in the current climate.The rates of conversion areas for Picea crassifolia,Sabina przewalskii,Potentilla fruticosa,Caragana jubata and Rhododendron capitatum are 12.40%-21.70%,26.42%-35.43%,19.55%-24.57%,39.11%-46.41% and 18.85%-21.79%,respectively.The area of transformation between adjacent grades is larger than that between non-adjacent grades,and the amount of transformation between unsuitable and low suitability is dominant.(6)Climate change leads to the translocation of species distribution.In view of elevation,Picea crassifolia,Sabina przewalskii,Potentilla fruticosa,Caragana jubata and Rhododendron capitatum move up 2.2-34.9 m,5.6-20.7 m,13.3-27.8 m,-28.3-5.1 m and-2.5-4.2 m,respectively.In view of horizontal direction,the translocation is relatively complex,most of which move northward,but some also move southward under different scenarios.(7)In the current vegetation pattern,the grassland area is the largest and the forest area is the second,accounting for 42.38% and 32.98%,respectively.In the future,forest land will increase 101.37%-107.29%,grassland will decrease 58.13%-63.12%,and forest land and grassland will account for 67.00% and 17.07% of the total area of the study area.