| Nicotiana alata Link et Otto,has high ornamental,commercial,medical and scientific values.Currently,the potential suitable habitats and the environmental factors affecting the distribution of N.alata are unknown.The Max Ent model is the most widely used for its best prediction results and simplicity of operation.In this paper,we optimized the Max Ent model by adjusting two model parameters of regularization multiplier and feature combination with the ENMeval package,and used the optimized Max Ent model to predict the potential suitable habitats of N.alata under current climate conditions based on the global geographical distribution data of N.alata and world bioclimatic variables,and analyzed the key bioclimatic variables affecting the distribution of potential suitable habitats of N.alata.The SSP1-2.6 and SSP5-8.5 scenarios for the 2050s and 2070s were used to predict the potential suitable habitats of N.alata under the future climate scenarios.The area change,spatial feature shift and the migration of the center of mass of N.alata suitable habitats under different climatic scenarios from current to the future were analyzed.The impact of climate change on N.alata potential suitable habitats was also analyzed.Finally,the multivariate environmental similarity surface(MESS)was used to analyze the extent of environmental changes in the N.alata suitable habitats under the global warming context and to provide a theoretical basis for the introduction and widespread cultivation of N.alata.The main conclusions are as follows:(1)Good accuracy of the model.AUC,TSS,and CBI were used to estimate the model accuracy,the results showd that all values were higher than 0.75,indicating a good accuracy of the model.(2)The precipitation of driest month,the mean temperature of the driest quarter,and the temperature annual range were the main bioclimatic variables that influenced the results of Max Ent prediction model construction.The total contribution of these four main bioclimatic variables were 82.1%.(3)The jackknife test showed that the mean temperature of the driest quarter,precipitation of driest month,precipitation seasonality,and max temperature of warmest month were the key bioclimatic variables affecting the distribution of N.alata.(4)The ecological characteristics of N.alata suitable habitats:the suitable range of the mean temperature of the driest quarter was-7-21°C,the suitable range of precipitation of driest month was 15-207 mm,the suitable range of precipitation seasonality was 1-45,and the suitable range of max temperature of warmest month was 17-34°C.(5)Under current climate conditions,the global potential suitable habitats and the actual suitable habitats of N.alata were similar and were mainly located in parts of southern North America,South America,Europe,and Oceania.The area of the high suitable habitats was2.52×10~6 km~2,accounting for 13.88%of the total suitable habitats area.The area of moderate suitable habitats was 4.7×10~6 km~2,accounting for 25.88%of the total suitable habitats area.The area of the low suitable habitats was 10.94×10~6 km~2,accounting for 60.24%of the total suitable area.(6)Under current climate conditions,the potential suitable areas for N.alata in China were mainly located in East China,Central China and South China,and the total suitable area was 2.28×10~6 km~2.(7)The global range of potential suitable habitats for N.alata varied slightly under different future climate scenarios.In the SSP1-2.6 and SSP5-8.5 scenarios of 2050s and 2070s,the range of the moderate and high suitable habitats of N.alata tended to expand and the range of the low suitable habitats decreased.In the SSP5-8.5 scenario for 2070s,the global potential suitable habitats for N.alata were the largest,18.51×10~6 km~2,with an increase of3.5×10~5 km~2 compared with the current climate.In the SSP1-2.6 scenario for 2070s,the global potential suitable habitats of N.alata were the smallest,17.88×10~6 km~2,with a decrease of 2.8×10~5 km~2 compared with the current climate.Under different climate scenarios in 2050s and 2070s of the future,the center of mass of the global suitable habitats of N.alata migrated to higher latitudes(northeast)as the temperature gets higher,and under SSP5-8.5scenarios in 2070s,the center of mass of the suitable habitats of N.alata had the farthest migration and therefore the higest latitude.(8)Under different future climate scenarios,changes in the potential suitable habitats of N.alata in China occurred mainly in southern and central China.Under the SSP1-2.6 and SSP5-8.5 scenarios in the 2050s and 2070s,the range of moderate and high suitable habitats of N.alata expanded and the range of low suitable habitats decreased.Under the future climate scenarios,the total area of N.alata suitable habitats increased only under the SSP1-2.6 scenario in 2050s,and the potential suitable habitats decreased under the rest of the future climate scenarios.The migration trajectory of N.alata in the potential suitable habitats in China varied under different future scenarios.(9)In 2050s and 2070s,there were no climate anomalies in the global potential suitable habitats of N.alata,and the difference in environmental climate change in the potential suitable habitats of N.alata became larger as the climate warms. |
