基于MaxEnt优化模型的闽楠潜在适宜分布预测

闽楠是我国二级保护珍稀濒危植物,不仅是珍贵用材树种,还具有重要的生态价值,预测其潜在适生区变化具有重要意义。采用Enmeval优化包调用MaxEnt模型建立最优模型。基于186条分布记录和9个环境变量模拟闽楠现代2050和2090年代的6个气候情景潜在分布区。综合Jackknife检验、置换重要值和贡献率、多元相似度面和最不相似变量,探讨影响闽楠适生分布区的环境因子,并分析空间变换格局。结果表明：（1）最优模型的参数为：FC=PT,RM=0.5,Maxnnt模型的预测准确度极高,AUC=0.9846±0.0037,现代闽楠潜在适生区的面积为54.32×10⁴km²,闽楠现代高度适生区集中分布在湖南南部和广西东北部;（2）在未来6种气候变化情景下,闽楠潜在适生分布区均有向北扩张的趋势,除2050s-SSP585外,其余情景适生区面积均增加较小,特别是情景2090s-SSP126下,高度适生区将减少40.32%;（3）最干月降水量（bio14）、降水季节性变化（bio15）、最冷月最低温（bio6）、最暖季降水量（bio18）和最暖月最高气温（bio5）是制约闽楠分布格局的主要环境因子;（4）闽楠各个时期的地理分布范围差别较大,说明闽楠对气候变化抗逆性较差,滥砍滥伐、生境破坏和自身繁育问题可能是致濒的重要原因,福建、江西、湖南和广西东北部是闽楠的稳定适生区和未来气候避难区,台湾中部、福建、江西、湖南、湖北西南部和浙南为理想的闽楠人工林引种区,随着气候变暖的日益加剧,粤桂黔三省（区）丧失区面积比较大,并建议对粤桂黔群体进行优先保护。

Prediction of potential suitable distribution of Phoebe bournei based on MaxEnt optimization model

Phoebe bournei is a rare and endangered plant under second-class protected plant in China. It is not only a valuable timber tree species, but also has important ecological value. It is of great significance to predict the changes of its potential suitable areas. In order to establish the optimal model, we use the maximum entropy (MaxEnt) optimized by the Enmeval data packet. Based on 186 distribution records and 9 environmental variables, the potential distribution areas of six climatic scenarios in 2050s (average of 2041-2060) and 2090s (average of 2081-2100) were simulated. Integrating Jackknife test, important value and contribution rate of replacement and the limited environmental factors, the environmental factors affecting the suitable distribution area of P. bournei were discussed. The results show that (1) the parameters of the optimal model are FC=PT, RM=0.5, Maxnnt model has high prediction accuracy, the area under the receiver operating characteristic curve (AUC) of 0.9846±0.0037. The total suitable area of the modern potentially geographical distribution of P. bournei 54.32×10⁴km². The modern highly suitable areas of P. bournei are concentrated in northeast Guangxi and southern Hunan. (2) In the prediction of the future suitable growth areas, the potential suitable growth areas under the six climate scenarios all expanded northward, with the exception of 2050s-SSP585; the other scenario suitable areas increased slightly, especially under the scenario 2070s-SSP126, the highly suitable areas will be reduced by 40.32%. (3) The precipitation of the driest month (bio14), precipitation seasonality (coefficient of variation) (bio15), minimum temperature of the coldest month (bio6), precipitation of the warmest quarter (bio18), and maximum temperature of the warmest month (bio5) are important environmental factors restricting the distribution pattern of P. bournei. (4) The geographical distribution range of P. bournei in different periods was quite different, which indicated that P. bournei had poor resistance to climate change. Deforestation, habitat destruction and self breeding problems may be the important reasons for its extinction. Fujian, Jiangxi, Hunan and southern Zhejiang are stably suitable areas and future climate refuge areas for P. bournei. The central Taiwan, Fujian, Jiangxi, Hunan, southwest Hubei, and southern Zhejiang are ideal introduction areas of P. bournei plantation. With the aggravation of climate warming, most areas of Guangdong, Guangxi and Guizhou will no longer be suitable for the growth of P. bournei, and it is suggested that priority should be given to the protection of the population in Guangdong, Guangxi and Guizhou.