末次盛冰期以来红豆树在不同气候变化情景下的分布动态

红豆树(Ormosia hosiei Hemsl. et Wils.)是中国的特有种,具有极高的经济价值、景观价值和药用价值。由于木材珍贵,人工盗伐严重,其种群数量和分布范围不断减少,被世界自然保护联盟(IUCN)濒危物种红色名录列为近危物种。气候变化会对物种的分布造成严重影响,理解该影响将有助于物种保护策略的制定,尤其是为濒危物种未来的保护提供重要参考。本研究基于红豆树在中国的地理分布数据,借助经相关性分析后筛选出的9个变量因子,利用最大熵模型(MaxEnt)模拟红豆树在末次盛冰期、全新世中期、当代和未来气候情景下的潜在分布区和影响其分布的主导环境因子,并且通过空间分析模拟其在不同气候变化情景下空间分布格局的变化。结果表明MaxEnt在各时期训练集和测试集的AUC(受试者工作特征曲线下的面积)均值均达到0.9以上,表明模型有很好的预测能力。刀切法(Jackknife)表明年均降水量、温度季节性变化标准差和昼夜温差月均值是主导其分布的三大因子,累计贡献率达到91.8%。将模拟结果导入到ArcGIS后,处理得到不同时期红豆树适生区空间分布格局变化。结果表明,自末次盛冰期以来,红豆树的适生区面积收缩且向北迁移;随着全球气候变暖,未来4种气候情景下红豆树适生区也有较大面积的减少,特别是在高浓度排放情景(RCP8.5)下,丧失率最高达到45.6%。重庆、江西及位于粤桂两省中南部的大面积适生区可能都将丧失。而新增区域仅存在于适生区的边缘,新增率仅为1%—2%。本研究表明红豆树的分布受气候变化的影响较大,该研究结果将对未来红豆树的迁地保护与栽培提供重要参考。

The distribution dynamics of Ormosia hosiei under different climate change scenarios since the Last Glacial Maximum

Ormosia hosiei Hemsl. et Wils. is endemic to China with high economic, landscape, and medicinal value. Due to the precious wood of this species, and as a result of serious logging, its population and distribution range are decreasing constantly. Thus, it is listed as a Near-Threatened species in the IUCN Red List of Endangered Species. Climate change will have a serious impact on the distribution of such species. Understanding the impact of climate change on species distribution will help develop species conservation strategies, especially for the future protection of endangered species. Based on geographical distribution data of O. hosiei in China, nine variable factors were selected after correlation analysis. The maximum entropy model (MaxEnt) was used to simulate the potential distribution in four scenarios, the Last Glacial Maximum, the Mid Holocene, the current and the future, and found the dominant environmental factors respectively. In addition, the spatial patterns under different climate changes have been modeled through space analysis in the MaxEnt. The results showed that the average AUC values in each period exceeded 0.9, which meant the MaxEnt model was of high predictive ability. Differences in the annual precipitation, temperature seasonality, and monthly mean temperature were predicted to be three dominant factors by the Jackknife method, and the contribution of these three factors reached 91.8%. Then, the simulation results were imported into ArcGIS to obtain the dynamics of the O. hosiei distribution pattern under different scenarios. The results showed that, since the Last Glacial Maximum, the potential distribution of O. hosiei contracted and the species migrated to the northward. With growing global warming, the potential distribution of O. hosiei under the four climate scenarios would also decrease; especially the scenario with the highest greenhouse gas emissions (RCP 8.5), the rate of loss peaked at 45.8%. Large suitable areas in Chongqing, Jiangxi, and south-central Guangdong and Guangxi provinces may be lost,while the expanding areas would only increase 1%-2% on the edge of the suitable area. In this research, it was found the distribution of O. hosiei was greatly effected by the climate change, which would provide an important reference for the future conservation and cultivation of O. hosiei.