基于Maxent模型的藏川杨青藏高原生态适宜性研究

A study on the Ecological Suitability of Typical Ecological Tree Species on Qinghai-Tibet Plateau:A Case Study of Populus Szechuanica

青藏高原生态安全是高原及其周边地区的安全保障,而藏川杨作为分布海拔最高的高原杨属植物,是高原生态中重要的一环。本文利用Maxent模型,对藏川杨的潜在分布适宜区进行预测,并为高原藏川杨的科学研究提供支撑。本文选择的青藏高原典型生态树种为藏川杨,整理得到127个样本数据和15个环境数据,导入Maxent模型中,预测适宜区范围,通过ROC曲线检验结果的准确度,并结合预测结果与青藏高原的生态安全屏障保护与建设规划进行讨论,结果如下:(1)测试结果AUC值中训练集为0.984,测试集为0.977,模型稳定程度高、预测结果较好;(2)环境因子贡献度由大到小排序为:最冷月最低温(bio06)>降水的季节性(bio15)>土壤酸碱度(Phiclk)>温度的季节性(bio04)>最暖月最高温(bio05)>最湿润月降水(bio13)>等温性(bio02)>海拔(Altitude)>最干季均温(bio09)>最冷月均温(bio11)>土壤有效水分(Plant available water)>土壤持水量(Field capacity)>年均温(bio01)>年降水(bio12c)>最冷季降水(bio19);(3)总适宜区面积为3.4×10^7km^2,适宜度等级6以上的区域总面积为54788km2,适宜区域主要集中于西藏的雅鲁藏布江沿岸,南至中国西藏边境县,四川、云南的三江流域沿岸。结论如下:(1)Maxent模型在稳定性高,预测范围准确,应用于青藏高原的预测结果较好;(2)对藏川杨影响最大的是bio06(最冷月最低温)和bio15(气温的季节性),贡献率分别是43.56%和16.35%,植被恢复时可重点考虑当地的该两项指标;(3)HIS指数是模型预测的结果划分依据,适宜度高于0.3的区域可作为青藏高原藏川杨生态规划适宜生长地区,重点进行植被恢复;(4)青藏高原西藏地区人口较少,可与生态保护区结合划分藏川杨生态保护与恢复区域;西南三江流域人口分布密集,可结合当地土地利用规划进行植被恢复。

The ecological security of the Qinghai-Tibet Plateau is the security guarantee of the plateau and its surrounding areas.In this paper,the Maxent model was used to predict the potential distribution suitable for Populus szechuanica,which provided support for the scientific research of Populus szechuanica on the plateau.This article selected Qinghai-Tibet plateau ecological species called Populus szechuanica as the typical objective.One hundred and twenty-seven sample data and fifteen environmental data were collected and imported into the Maxent model to predict the range of suitable areas.The accuracy of the results was tested by the ROC curve,and the prediction results were combined with the Qinghai-Tibetan protection and construction planning of ecological security barriers on the plateau.The AUC value of the test results was 0.984 for the training set and 0.977 for the test set,indicating a good prediction result.The environmental factor contribution in descending order were bio06,bio15,Phiclk,bio04,bio05,bio13,bio02,altitude,bio09,bio11,plant available water,field capacity,bio01,bio12,bio19.What’s more,the total area of the suitable area was 3.4×10^7 km^2,and the total area of the area above grade 6 was 54788 km~2.On the other hands,the suitable area was mainly concentrated along the Yarlung Tsangpo river in Tibet,south to Tibet border county in China,and along the Sanjiang river basin in sichuan and yunnan.Furthermore,the Maxent model had high stability,accurate prediction range and good prediction results when applied to the Qinghai-Tibet plateau.Bio06(min temperature of coldest month)and bio15(precipitation seasonality)had the greatest impact on the populus szechuanica,with the contribution rates of 43.56%and 16.35%,respectively.These two indicators could be considered during vegetation recovery.HIS index was the classification basis for the results predicted by the model,and the area with a suitability of more than 0.3 could be used as the suitable growth area for the ecological planning of the Tibetan poplar on the Qinghai-Tibet Plateau,focusing on vegetation restoration.The results also indicated that the Tibetan area of the Qinghai-Tibet Plateau had a small population,which could be combined with the ecological protection zone to divide the ecological protection and restoration of Tibetan and Sichuan poplar.However,the population of the Sanjiang River Basin in Southwest China was densely distributed,so vegetation restoration could be carried out according to the local land use planning.