Priority Analyses On Introduction Of Five Exotic Garden Tree In China Under Climate Change

With the development of economy and technology,problems of global warming and environmental degradation is getting worse,which bring challenges to the survival,introduction and utilization of plants.Especially for some introduced garden trees,due to the lack of introduction practice in the introduction area,it is easy to cause losses due to improper selection of species.The ornamental trees which are Spathodea campanulata,Brachychiton acerifolius,Delonix regia,Cassia fistula and Jacaranda mimosifolia are introduced in China and originated in different regions of the world.They are loved and widely popular all over the country,however,their suitable region of introduction in China is relatively unclear,and there is the possibility of blind introduction.It is necessary to analyze the suitable region of introduction.In this study,the niche Max Ent model software with excellent reliability and stability was used.Based on the geographic information of the distribution data,the climate factor data was retrieved for modeling and model verification.Arc GIS was used to assist in data conversion and layer expression.The five exotic garden trees of Spathodea campanulata,Brachychiton acerifolius,Delonix regia,Cassia fistula and Jacaranda mimosifolia are predicted to be suitable for introduction under current and future climate conditions,and the suitability of introduction is divided into five garden trees based on actual introduction and cultivation performance.Provide guidance on the application of garden landscape in China.The main contents of this research include:(1)Data acquisition and screening: The distribution data were sourced from the GBIF website and the PPBC website respectively,and the distribution data were screened by methods such as specimen review,references tracking,and image comparison.583 entries,220 entries,927 entries,498 entries and 866 entries distribution data of five trees were obtained.The buffer analysis method is further used to screen the distribution data to avoid overfitting of the model simulation.The environmental factor data comes from 19 bioclimatic factors on worldclim.In order to avoid overfitting of the model,the pearson correlation analysis method is used to remove highly correlated environmental factors greater than 0.8.(2)Model establishment and verification: using the screened distribution data and optimized environmental factors,the Max Ent model software is used to model and verify the five tree species.The ROC curve test results of the model showed that the AUC values of the five trees were 0.922,0.984,0.911,0.926,0.938,and the model evaluations were all excellent,indicating that the model prediction results are highly reliable,which can be used for introduction suitability analysis.(3)Comparison of the suitable range of introduction of five trees in China under current climatic conditions: Combining the introduction and cultivation performance of five trees to classify the model prediction map,the results show: Spathodea campanulata,Brachychiton acerifolius,Delonix regia,Cassia fistula and Jacaranda mimosifolia are native to tropical Western Africa,Australia,Madagascar,India,Myanmar,Sri Lanka,Brazil,Argentina,and Bolivia.They can be successfully introduced in southern China,but the five trees do not completely overlap in the suitable introduction areas of China.Under current climatic conditions,the most suitable distribution areas shared by these five trees in China are Yunnan province(Chuxiong,Yuxi,Simao,Gejiu,Wenshan,Jinghong)and Fujian province(Xiamen,Zhangzhou,Fuzhou,Quanzhou,Putian).The more suitable distribution area for Jacaranda mimosifolia is Kunming,Yunnan province.Based on the Jackknife method,the main environmental factors that affect the suitable range of five trees respectively are: min temperature of coldest month and precipitation of wettest quarter(Spathodea campanulata);temperature annual range and isothermality(Brachychiton acerifolius);min temperature of coldest month and precipitation of wettest month(Delonix regia);min temperature of coldest and month precipitation of wettest month(Cassia fistula);temperature annual range and min temperature of coldest month(Jacaranda mimosifolia).Since the five trees are native to different climatic conditions and have certain adaptability,the successful introduction of five garden trees in a specific area(such as Guangzhou)does not mean that any other places where one of the trees can be introduced can also be successfully introduced.For the other four types of trees,beware of the risks caused by blind inferences when introducing them.(4)Changes in the suitable range of the introduction of five trees under future climate conditions: The distribution data is again used to retrieve the climate database under different carbon emission models(Rcp2.6 low emission and Rcp8.5 high emission),and Maxent predicts the suitable introduction range of five trees changes in the future.The results show that the suitable range of Spathodea campanulata,Delonix regia and Cassia fistula expands to higher latitudes with the increase of carbon dioxide emissions.Under the Rcp8.5 high emission,the suitable range is increased more than under the Rcp2.6 low emission,and can be extended to the middle and lower reaches of the Yangtze River at most.However,the suitability of Brachychiton acerifolius and Jacaranda mimosifolia in southern China is showing a downward trend.Such regions need to be alert to the increased risk of introduction in future climates.