基于优化的MaxEnt模型预测赤水蕈树的潜在适宜区

Potential suitable area of Altingia multinervis predicted by optimizated MaxEnt model

关键词:  赤水蕈树, MaxEnt模型, 潜在适生区, 环境因子, 避难所

Key words:  Altingia multinervis, MaxEnt model, potential suitable area, environmental factors, refuge

摘要:

赤水蕈树(Altingia multinervis)具有较高的经济和药用价值,但由于气候变化和人类活动的强烈干扰,使其野生种质资源已近枯竭,被列为国家二级保护植物。为重建末次间冰期以来赤水蕈树地理分布格局变化过程、了解环境因子对潜在适宜区的制约机制,为赤水蕈树及其周围野生动植物的栖息地保护和引种栽培提供可靠的科学依据,该文运用MaxEnt模型结合地理信息系统ArcGIS软件模拟赤水蕈树潜在适生区及其空间变化格局,利用贡献率(PC)、置换重要值(PI)和刀切图评估制约现代地理分布的主导因子。结果表明:(1)优化的MaxEnt模型预测精度极高,AUC值大于0.97; 赤水蕈树现代潜在适生区主要集中分布在贵州、四川和重庆交界的长江流域周围,其中以贵州赤水河流域为最佳适宜区; 昼夜温差月均值(bio2)、年降水量(bio12)、降水季节性变化(bio15)和温度年较差(bio7)四个关键环境因子影响赤水蕈树的地理分布。(2)现代赤水蕈树潜在中高适生区面积2.692 6×10⁴ km²,末次间冰期、全新世中期、未来时间段(2041—2060年、2061—2080年)低浓度(RCP2.6)和高浓度(RCP8.5)的中高适生区面积分别是2.277 3×10⁴、2.831 0×10⁴、2.159 6×10⁴、2.605 1×10⁴、2.330 4×10⁴、2.460 4×10⁴ km²。(3)在未来4种排放情景下,赤水蕈树新增的面积集中在四川和贵州区域,而在过去的全新世中期则集中分布在重庆区域。综上结果表明,赤水蕈树分布范围狭窄,而赤水河流域独特的地形优势可能是其避难的主要场所。

Abstract:

Altingia multinervis has been listed as a second-class protected plant in China., with high economic and medicinal values. However, its wild germplasm resources have been nearly exhausted due to the strong disturbance of climate change and human activities. Here, we aim to simulate the changes in the geographical distribution pattern of A. multinervis since the last interglacial(LIG)and to explore how climatic factors restrict the potential suitable areas, to provide a reliable scientific basis for habitat protection and cultivation of A. multinervis and its surrounding wildlife. In this study, based on optimized MaxEnt model and ArcGIS software, we simulated the potential suitable areas of A. multinervis and its spatial change pattern. The importance of environmental factors that constrains current geographical distribution was evaluated by percent contribution(PC), permutation importance(PI)and Jackknife test. The results were as follows:(1)The prediction accuracy of the optimized MaxEnt model was extremely high, as indicated by the value of the area under the receiver operator characteristic curve over 0.97. The potential suitable areas of A. multinervis for the present distribution were mainly distributed in the Yangtze River basin at the junction of Guizhou, Sichuan and Chongqing, of which the best suitable area was around Chishui River basin in Guizhou. The key environmental factors affecting the potential distribution of A. multinervis were mean diurnal range(bio2), annual precipitation(bio12), seasonality of precipitation(bio15)and range of annual temperature(bio7).(2)The potential middle-high suitable area of A. multinervis in current was 2.692 6×10⁴ km², in last interglacial(LIG)was 2.277 3×10⁴ km², in the mid-Holocene(MH)was 2.831×10⁴ km², in four future scenarios were 2.159 6×10⁴ km²(2050s RCP2.6), 2.605 1×10⁴ km²(2050s RCP8.5), 2.330 4×10⁴ km²(2070s RCP2.6), 2.460 4×10⁴ km²(2070s RCP8.5), respectively.(3)Under the four future discharge scenarios, the newly increased area of A. multinervis was concentrated in Sichuan and Guizhou, while it was concentrated in Chongqing in the mid-Holocene. All the above results indicate that the distribution range of A. multinervis is narrow and the potential suitable area is very small, and the unique topographic advantage of Chishui River Basin may be the main refuge place of A. multinervis.