气候变化情景下西藏入侵植物印加孔雀草的潜在分布预测

入侵植物通常由于具有较强的适应性而能够快速繁殖扩散，影响本土物种的生长繁殖，进而威胁到当地生态安全、景观格局和农业生产等。西藏生态环境非常脆弱，一旦发生恶性物种大面积入侵，生态后果不堪设想。为了探究入侵植物印加孔雀草(Tagetes minuta L.)对西藏东南生态安全的影响趋势，基于野外实地调查数据，采用最大熵(MaxEnt)模型，应用R语言平台对模型和数据进行优化筛选，探讨影响其地理分布的主要环境因子，并模拟预测了当代及2种气候变化情景(RCP 4.5、RCP 8.5)下，其在西藏的潜在适生区分布情况。结果表明：(1)训练数据集和测试数据集的受试者工作特征曲线下的面积(AUC) 均为0.997，模拟效果较好；底层土壤酸碱度、最暖季降水量、土壤有效含水量、最暖月最高温度为影响印加孔雀草分布的主导环境因子，贡献率总和超过90%。(2)加查县、朗县是印加孔雀草分布密集区域，米林县、林芝市区、察隅县、墨脱县等地为入侵高风险地区。(3)中短期(2050年)内印加孔雀草适生面积增加明显，2070年时面积则会减少；印加孔雀草适生区在藏东南地区进一步向东北区域扩张，分布质心由当前的墨脱县域向波密县域转移。总体而言，印加孔雀草分布受土壤环境、温度和降水影响较大，气候变化将使其向西藏东部、南部扩张。研究结果对于西藏自治区制定植物入侵防控管理办法具有重要参考价值。

Prediction of potential distribution of the invasive plant Tagetes minuta L.(Wild Marigold) in Tibet under climate change

Invasive plants, which could multiply and spread rapidly due to their strong adaptability, affect the growth and survival of native species, and thus threaten the local ecological security, landscape and agricultural production. Since the ecological environment of Tibet is vulnerable, once the large-scale invasion of malignant species occurs, the consequences of ecological are unimaginable. In order to investigate influence of invasive plant Tagetes minuta L. on the ecological security in southeastern Tibet in this study, the adopted MaxEnt model based on the data of field survey was used to explore the main environmental factors which contributed to its geographic distribution, and simulate the distribution of potentially suitable areas in Tibet under contemporary and two climate change scenarios (RCP 4.5, RCP 8.5) by the R language platform. The results show that:(1) both the area under the receiver operating characteristic curve (AUC) of training and test data set were 0.997, indicating that the simulation effect of the model was good. Acidity of the underlying soil, precipitation in the warmest season, available water storage capacity of the soil and max temperature of the warmest month were the main environmental factors affecting the distribution of Tagetes minuta L., and the total contribution rate was more than 90%. (2) Jiacha County and Lang County are the most densely distributed areas of Tagetes minuta L. based on the field survey. Milin County, Linzhi City, Chayu County and Motuo (Medog) County will be the high-risk areas for Tagetes minuta L. invasion based on field survey and model prediction. (3) The suitable and potential area for growth and clonization of Tagetes minuta L. would increase significantly in the middle and short term (2050s), but will decrease in the 2070s based on the model simulation. The suitable area of Tagetes minuta L. would expand furtherly in the southeast of Tibet and will expand to the northeastern area, and its distribution center would move from the current Motuo County to Bomi County. In general, the distribution of Tagetes minuta L. was greatly affected by soil environment, temperature and precipitation, and climate change would make it expand more wildly to the east and south area of Tibet. The results could help to provide theoretical support for Tibet to formulate prevention and control strategies for invasive species.