基于最大熵模型的中药材木贼麻黄潜在适生区

木贼麻黄(Ephedra equisetina)具有重要的药用和经济价值,在水土保持、生态平衡、荒漠化防治等方面也发挥重要作用,被列为国家二级保护植物。全球气候变化和人类活动严重威胁到木贼麻黄资源保护与利用,因而预测其潜在适生区空间变化具有重要意义。基于最大熵(MaxEnt)模型和ArcGIS软件,结合201条木贼麻黄在中国的有效分布记录和21个环境变量,预测在自然环境影响及人类活动干扰下中药材木贼麻黄适生区分布,并将木贼麻黄高适生区与土地利用类型进行叠加分析。结果表明:(1)模型添加人类活动因子后曲线下面积(AUC)值由0.919升至0.948,预测结果精度提高,而添加人类活动因子使木贼麻黄适生区面积严重减少,部分适生区等级退化,其分布愈破碎化稀疏零散;(2)木贼麻黄适生区多集中分布于新疆、甘肃、宁夏、陕西和山西地区,未来时期两种情景下木贼麻黄适生区都出现不同程度的扩张,RCP2.6-2050年相对当前时期高适生区面积增加最多;(3)参与建模的环境因子中贡献度较高的酸碱度(pH)、海拔(Altitude)和年平均温度(Bio1)对木贼麻黄地理分布有关键影响;(4)未来时期下木贼麻黄高适生区的几何质心出现不同程度向东迁移的现象,多分布于甘肃省境内;(5)木贼麻黄高适生区部分土地已经被开发利用,剩余未利用的土地分布于新疆、甘肃、内蒙古和宁夏地区,可在这些地区因地制宜发展木贼麻黄种植业。为木贼麻黄的就地、迁地保护、优先保护区以及人工种植选地提供理论依据,这对木贼麻黄资源保护与利用具有重要的现实意义。

Potentially suitable areas for traditional Chinese medicinal material Ephedra equisetina based on MaxEnt model

Ephedra equisetina as a national secondary protected plant has great medicinal and economic value. It also plays an important role in preventing water and soil erosion, keeping ecological balance, desertification governance and other aspects. However, the deterioration of the global climate as well as human activities seriously threatens the conservation and utilization of E. equisetina resources. Therefore, it is of great significance to predict the changes in the potential suitable areas of E. equisetina. Based on MaxEnt model and ArcGIS software, we combined 201 effective distribution records of E. equisetina in China and 21 environmental variables selected, this study predicted the changes of potential suitable areas of Chinese herbal medicines E. equisetina under two scenarios of natural environmental disturbance and human activity disturbance in the future. In addition, the predicted highly suitable areas of E. equisetina and land use types were superimposed by analysis. The results showed that: (1) After adding the human activity factor to the MaxEnt model, the area under curve (AUC) increased from 0.919 to 0.948, and the accuracy of the prediction results was improved. However, we noticed that the area of the totally suitable areas of E. equisetina under the disturbance of human activities was seriously reduced, and some of the suitable levels had degraded, with the distribution of suitable areas became more sparse, scattered and fragmented. (2) The suitable areas of E. equisetina were mostly distributed in Gansu, Ningxia, Shaanxi, Shanxi, and Xinjiang. Both scenarios for the future period showed different degrees of expansion in the suitable areas of E. equisetina. Compared with the current period, the representative concentration pathways of 2.6 for the period of 2050 (RCP2.6-2050), which has the largest increase in the highly suitable areas of E. equisetina. (3) Acidity and basicity (pH), altitude (Altitude) and annual mean temperature (Bio1), which were the higher contributors among the 21 environmental factors involved in the modeling, and these three factors had a significant influence on the geographical distribution of E. equisetina. (4) The geometric centroid of the highly suitable areas was projected to move eastward, distributed mostly in Gansu Province. (5) Some parts of the land in the potentially highly suitable areas of E. equisetina had already been developed and utilized, and the remaining little unused land was distributed in Xinjiang, Gansu, Inner Mongolia and Ningxia, where could be suitable for the development of E. equisetina cultivation industry according to local conditions. All of these provide the theoretical basis for in-situ conservation, ex-situ conservation, priority protection areas and site selection for artificial cultivation of E. equisetina, which is of great practical significance for the protection and sustainable utilization of E. equisetina resources.