| Climate warming is the main trend of climate change in the future.climate change geographic distribution of plant species is influenced by climate change.The study of the influence of climate change on the species geographic distribution is of great significanc for protection and proper utilization of species.In this study,we adjusted multi-features combination and magnification parameters through ENMeval packet to optimize MaxEnt model.With 221 effective distribution data of Corylus mandshurica and 16 environmental factors,the study simulated and predicted its potential distribution areas under current climate scenario,analyzed dominant environmental factors affecting its geographic distribution and the suitable survival range of Corylus mandshurica.Then utilizing three representative concentration pathways(RCP2.6,RCP4.5,RCP8.5)in the future 2050 s and 2070 s simulate and predict the suitable habitat range of Corylus mandshurica under the future climate scenario.The effects of climate change on the geographical distribution of Corylus mandshurica were analyzed by exploring the spatial transfer characteristics of suitable area,area variation and centroid migration regulation of suitable area from the present to the future.Finally,the change degree of suitable area and main factors influencing the changes in distribution pattern were evaluated by multivariate environmental similarity surface analysis and the most dissimilar variable analysis.In order to provide reference value for the protection and rational development of Corylus mandshurica.The main conclusions are as follows:(1)when feature combination was linear,quadratic,threshold and product features,and regularization multiplier was 1.5,both the complexity and over-fitting of the model are lower than the default parameters,and the values of training AUC and test AUC are greater than0.8,indicated that the model is accurate.Therefore,the FC=LQHP,RM=1.5 was set to the optimized.(2)under the current climatic conditions,the suitable distribution area of Corylus mandshurica accounts for about 28.3% of China's the land area,which is mainly concentrated in north China,northeast China and the south east of the northwest China,showing a zonal distribution.Highly suitable area accounts for about 6.0% of China's land area,and the highly suitable area is mainly located in Changbai Mountain,Taihang Mountain,Qinling-Daba Mountain and adjacent areas.The distribution data of Corylus mandshurica is not locted in Xinjiang,but the prediction results show that there are a few suitable areas of Corylus mandshurica in Xinjiang.(3)Dominant environmental factors affecting the geographic distribution of Corylus mandshurica were annual precipitation,mean temperature of driest quarter,elevation and annual average temperature,the contribution rate of which reached 78.8% cumulatively,and proper condition ranges above were 430-970 mm,-21-3 ?,40-2800 m and 0.8-13 ?respectively.(4)Under the different emission scenarios of 2050 s and 2070 s in the future,the suitable areas of Corylus mandshurica showed an increase in the adaptive ability in the northeast China and the eastern part of Inner Mongolia,from low suitable areas to medium and high suitable areas,and the scope of the suitable area expanded.While the suitable area in southwest China gradually shrunk.Under the future climate scenario,compared with the current,medium and high suitable areas of Corylus mandshurica have increased,low suitable areas have decreased,and the total area of suitable distribution areas have changed little compared with the current.Comprehensive analysis shows that the adaptability of Corylus mandshurica is improved under climate change.Under the future climate scenario,the migration trajectory of the center of the suitable zones of Corylus mandshurica is different under different representative concentration pathways,but it is comprehensively analyzed that the center of the suitable zones of Corylus mandshurica tened to move toowards northeast.(5)under the different climate scenarios of 2050 s and 2070 s in the future,the areas of climate abnormal in the potential distribution areas of Corylus mandshurica will gradually increase with the increase of gases emission grade.Under the background of future climate change,the climate anomaly areas of the suitable habitats mainly appears in the south,southwest and eastern of the suitable habitats,in which the most dissimilar variable in the south is the mean diurnal temperature range.The most dissimilar variable in the southwest is the mean temperature of warmest quarter,and the most dissimilar variable in the northeast is isothermality.Thus it can be seen that the temperature factor is the main factor limiting the distribution of Corylus mandshurica under the background of climate warming. |
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