| Phoebe bournei is a unique tree species in China.Due to its difficulty in seed germination and natural regeneration,and suffering from natural and man-made destruction,the number of existing wild individuals is scarce and natural resources are facing exhaustion.It was listed as a national second-class protected rare plant.Under climate change,rare and endangered plants are facing the risk of extinction due to difficulties in migration.What are the advantages and disadvantages of climate change on P.bournei? How do P.bournei respond to climate change? How to protect and utilize the natural resources of P.bournei reasonably and effectively and how to scientifically introduce species need to be solved urgently.Through a combination of field investigation and resource retrieval,based on the climate,soil,elevation factors and the distribution points of P.bournei,species distribution models and geographic information technology were used to predict the potential suitable distribution areas under the last interglacial period,last glacial maximum,mid-Holocene,current,the future of low radiative forcing scenarios SSPS2.6,medium radiative forcing scenarios SSPS4.5,medium-high radiative forcing scenarios SSPS7.0,and high radiative forcing scenarios SSPs8.5 in 2030 s,2050s,2070 s and 2090 s.The environmental factors and response curves affecting the distribution of the suitable area of P.bournei were determined,and the spatial pattern and centroid migration of P.bournei resources were summarized.The research results are as follows:1.The accuracy evaluation shows that AUC values of MaxEnt,Bioclim,Domain and ENFA are all greater than 0.9 and Kappa values were all greater than 0.7.The prediction accuracy of the four models was good,but the accuracy and range of MaxEnt’s predictions performed better,so the MaxEnt optimization model was used for this prediction.In the comprehensive evaluation,the main environmental factors affecting the current geographical distribution of P.bournei were precipitation in January,annual precipitation,elevation,precipitation in July,temperature seasonality,and mean diurnal range,and precipitation factors play a dominant role.The suitable threshold of precipitation in January was16.5-68 mm,the suitable threshold of annual precipitation was 1 120～3675 mm,the suitable threshold of elevation was 120～1 400 m,the suitable threshold of precipitation in July was 95～365 mm,the suitable threshold of temperature seasonality was 44.50～87,the suitable threshold of mean diurnal range is 5.1～9.6 ℃.2.At present,the distribution range of the total suitable areas of P.bournei in our country was 21.73°～31.98°N,102.64°～121.97°E.The highly suitable areas were mainly distributed between the mountainous hills at the junction of many provinces,such as the Yandang Mountain at the junction of Fujian and Zhejiang,the Wuyi Mountains at the junction of Fujian and Jiangxi,the Luoxiao Mountains at the junction of Hunan and Jiangxi,and the Nanling at the junction of Hunan,Jiangxi and Guangdong.The moderately suitable areas were mainly distributed in western Hunan,eastern Guizhou,and central Zhejiang.The poorly suitable areas were mainly distributed in Chongqing,western Guizhou,low mountains and hills at the junction of Hubei and Anhui,and a very small part of the Sichuan Basin.In the past and future periods,the distribution of suitable areas for P.bournei was roughly the same as the current prediction results of suitable areas.Under the circumstance that it was not hindered by topography,western Guizhou,central and western Hubei,Guangdong,southern Guangxi and southern Anhui was the potential distribution areas of P.bournei.3.In the past three periods,the total suitable area for P.bournei during the last interglacial period was the widest,and the total suitable area for the last maximum glacial period was the smallest.In the future,under the same climate scenario and different periods,the SSPs2.6climate scenario will have a positive impact on the development of P.bournei with time,while the SSPs4.5 climate scenario has no advantage on the development of P.bournei.SSPs7.0 and SSPs8.5 climate scenarios only expanded the suitable area of P.bournei in the 2090 s,but the development advantage of SSPs8.5 to P.bournei was smaller than that of the SSPs7.0 climate scenario.In general,the SSPs2.6 climate scenario has more development potential for the growth of P.bournei than the other three climate scenarios.Under different climatic scenarios,the increased and lost areas of P.bournei mainly occur in the periphery of the reserved area and relatively fragmented areas,such as central and western Hubei,central and western Jiangxi,Sichuan Basin,northwestern Chongqing,western Guizhou,a few low hills in the central and northern part of Guangdong and Guangxi,and northern Taiwan.4.From the last interglacial period to the current,the centroid of P.bournei has changed in the longitude and latitude directions,but the east-west migration amplitude of the centroid in the longitude is greater than the north-south migration in the latitude.From the current to the early stages of furture climate scenarios,the centroid migration trend of P.bournei was southeast,and the direction of centroid migration shows no obvious law with time change.Under the SSPs2.6 climate scenario,the centroid migration trajectory of the climate scenario was mainly located in the south of the centroid in the current period;the centroid migration trajectories of the SSPs4.5,SSPs7.0 and SSPs8.5 climate scenarios were mainly located in the south and east of the centroid in the current period.5.The current and future distribution of potential suitable areas were fuzzy and superimposed to obtain distribution map of P.bournei.Without being hindered by terrain and disturbed by human activities,the suitable distribution area ranges from 21.64°～32.44°N,102.65°～122.31°E.Comparing the suitable distribution area with the current,the range of the poorly,moderately and highly suitable areas of P.bournei has a certain expansion.Comparing the distribution area of those province,it was found that Fujian,Jiangxi,and Hunan are the highly suitable areas for the growth of P.bournei,the wild resources of P.bournei can be protected locally by setting up nature conservation sites in these areas.Central and eastern Guizhou,Guangdong,northwestern Guangxi,and southern Zhejiang are second-class suitable areas,ex-situ protection should be carried out for P.bournei,and regional forest experiment and demonstration bases and national reserve forest bases should be built.Western Guizhou,Guangxi,central and southern Guangdong,central and western Hubei,and southern edge of Anhui and parts of Sichuan and Chongqing may become new suitable areas for P.bournei under climate change,and these areas can be used as potential introduction and cultivation areas for P.bournei. |
