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末次盛冰期以来陀螺果潜在地理分布格局变迁预测

王璐1,2,许晓岗1,2,3*,李垚1,2   

  1. (1 南京林业大学南方现代林业协同创新中心, 南京 210037;2南京林业大学生物与环境学院, 南京 210037;3 江苏高等教育机构南京林业大学优势学科, 南京 210037)
  • 出版日期:2018-01-10 发布日期:2018-01-10

Prediction of  potential geographical distribution pattern change forMelliodendron xylocarpum HandelMazzetti since the Last Glacial Maximum.

WANG Lu1,2, XU Xiao-gang1,2,3*, LI Yao1,2   

  1. (1Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China; 2College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China;  3Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions at Nanjing Forestry University, Nanjing 210037, China).
  • Online:2018-01-10 Published:2018-01-10

摘要: 陀螺果(Melliodendron xylocarpum Handel Mazzetti)为中国特有种,观赏价值极高,了解陀螺果潜在地理分布格局对气候变化的响应对于有效保护和合理利用其野生资源具有重要意义。本文采用ENMeval数据包优化Maxent模型参数设置;基于137条现代地理分布记录和8个生物气候变量模拟和预测陀螺果在末次盛冰期、全新世中期、现在和典型浓度目标(RCP)8.5背景下2070年的潜在分布区;利用多元相似度面和最不相似变量分析,评估气候异常程度和引起气候异常的关键因子;综合使用贡献率、重要值和Jackknife法,检验评估环境因子的重要性。结果表明:当特征组合为线性、二次型、片段化、乘积型和阈值性,调控倍频为2时,模型复杂度和过拟合程度较低,此时测试集受试者工作特征曲线下的面积值达到0.9853±0.0055,模拟准确度极高;陀螺果现代高度适宜区位于广西、广东和湖南交界的地区;末次盛冰期其适宜分布区面积明显缩小,中国南部的适宜区向南转移;全新世中期适宜分布区面积增加,但无明显移动;2070年低海拔地区年均温和极端最高温最异常,适宜度显著降低,生境呈破碎化趋势,高、中度适宜区残存于高海拔地区;温度因子和降雨因子共同制约着陀螺果现代潜在地理分布,但前者更有可能引起地理分布的变迁。

关键词: 水分来源, 稳定同位素, 植物水势, 喀斯特, 出露基岩

Abstract: Melliodendron xylocarpum HandelMazzetti, a tree species endemic to China, is of extremely high ornamental value. To understand its response of potential geographical distribution pattern to climate change can shed light on effective protection and reasonable utilization of the species. In this study, we used ENMeval to optimize parameters of Maxent model. The potential distributions during different ages,e.g. the Last Glacial Maximum, midHolocene, present, and year 2070 under the scenario of representative concentration pathway 8.5 were simulated by the model based on 137 modern geographical distribution records and 8 bioclimatic variables. Also, the multivariate environmental similarity surface analysis and the most dissimilar variable analysis were used to evaluate the climate anomaly and its key influencing factors, while the percent contribution, permutation importance and Jackknife test were applied to assess the importance of each bioclimatic variable. The results showed that: (1) when the feature combination was linear, quadratic, hinge, product, and threshold, and regularization multiplier being 2, the complexity and degree of overfitting of the model were relatively low. As a result, the accuracy of the model was very high as indicated by the area under the receiver operator characteristic curve for test data up to 0.9853±0.0055. (2) The highly suitable region for the present distribution was at the junction of Guangxi, Guangdong, and Hunan provinces. During the Last Glacial Maximum, the area of the suitable region was significantly reduced and the suitable region in south China moved southward. In the midHolocene, the area of suitable region was increased but no obvious movement occurred. In 2070, the annual mean temperature and maximum temperature of warmest month were the most abnormal variables in low altitude regions, and highly and moderately suitable areas may remain in high altitude regions. (3) Both the temperature and precipitation factors restricted the potential geographical distribution of M. xylocarpum, but the former was more likely to lead to the change of geographical distribution.

Key words: stable isotope, karst, water source, rock outcrop, plant water potential