中国硬叶兜兰地理分布格局及其潜在分布区预测

该研究基于MaxEnt模型和ArcGIS技术，采用实地调查为主结合标本、文献查阅的方法得到全国107个硬叶兜兰有效分布点，并筛选出13个因子，从生态位模型角度对其潜在地理分布进行预测，并采用AUC值对模型进行准确性检验，用ArcGIS 10.6软件进行可视化处理，分析硬叶兜兰潜在分布区并计算面积；采用刀切法、预测因子贡献率和响应曲线，分析影响硬叶兜兰分布的主导因子，为硬叶兜兰的就地保护、迁地保护、野外回归和开发利用提供理论区划依据。结果表明：(1)硬叶兜兰在全国大尺度上总体呈零散分布，以滇、黔、桂三省(自治区)的喀斯特山地为主要分布区；小尺度上普遍呈现出微地形小居群聚集分布的特点，有64.95%的分布点实际分布面积不超过100 m²。(2)该种潜在分布区预测的构建数据和检验数据AUC值分别为0.992和0.987，其潜在分布区为贵州西南至南部地区、贵州中部地区、云南东南部、广西北部至西北部，其中最适宜区为滇东南、黔西南至桂西北地区，面积约3 912.71 km²。(3)影响硬叶兜兰潜在分布的主导因子及最适范围是顶层土壤质地(壤土)、最干季度降水量(55~85 mm)、年均降水量(1 220~1 480 mm)、碳酸钙含量(2.5%~2.7%)，4个主导因子的贡献率分别为30.0%、20.1%、16.2%和7.0%。研究认为，硬叶兜兰被采挖严重，对生境要求严格，结合该种在中国的实际分布情况、生存现状、受威胁状况和潜在分布区预测结果，建议将硬叶兜兰列入国家重点保护植物名录，并通过自然保护区或保护小区等方式加强原生地保护。

Geographical Distribution Pattern and Prediction of the Potential Distribution of Paphiopedilum micranthum in China

Based on MaxEnt model and ArcGIS technology, we obtained 107 effective distribution points of Paphiopedilum micranthum in China and screened 13 factors for MaxEnt model prediction through field investigation, combined with specimens and literature review. The AUC was used to analyze the reliability of the model and visual processing was carried out in ArcGIS 10.6 to analyze the potential distribution area of P. micranthum and calculated its size. Jackknife, the contribution rate of predictive factors and the response curve were used to analyze the dominant factors affecting the distribution of Paphiopedilum. The results showed that: (1) in general, P. micranthum distributed scattered in the large scale of the countrywide, and the karst mountains in Yunnan, Guizhou and Guangxi provinces (autonomous regions) are the main distribution areas. On a small scale, it generally presents the characteristics of micro topography and small population aggregation distribution, with 64.95% of the distribution points having an actual distribution area of not more than 100 m². (2) The potential distribution predicted the AUC of training data and test data, which are 0.992 and 0.987, respectively. Southwest to southern Guizhou, Central Guizhou, Southeast Yunnan and north to Northwest Guangxi are the potential distribution areas. The most suitable areas are Southeast Yunnan and southwest Guizhou to Northwest Guangxi, with an area of about 3 912.71 km². (3) The dominant factors affecting the potential distribution of P. micranthum are T_TEXTURE (Fine), precipitation of the driest quarter (55-85 mm), annual average precipitation (1 220-1 480 mm) and T_CaCO₃ (2.5%-2.7%). The contribution rates of the four dominant factors are 30.0%, 20.1%, 16.2% and 7.0%, respectively. We concluded that P. micranthum is excavated seriously and required the strict habitat. According to the actual distribution, survival status, threatened status and prediction results of potential distribution areas of P. micranthum in China, we suggest that P. micranthum should be included in the list of national key protected plants, and strengthen the native places protection through nature reserves or specific conservation region.