西南地区红花龙胆分布格局模拟与气候变化影响评价

Distribution simulation of Gentiana rhodantha in Southwest China and assessment of climate change impact

应用最大熵(MaxEnt)模型,基于230条分布记录及33个气候因子数据,模拟全新世中期(约6000年前)、当前时期(1950—2000年)和未来(2050s、2070s)气候条件下,红花龙胆西南地区的潜在分布范围;结合多元统计分析和ArcGIS空间分析,筛选影响物种分布的关键气候因子,探讨不同分布区对气候变化的敏感性.结果表明:模型训练集AUC值为0.942,验证集AUC值为0.849,表明模型预测的准确性较高.5个气候因子(7月最高气温、8月最低气温、昼夜温差与年温差比值、7月最低气温和6月最低气温)对模型贡献最大,累计贡献率达59.9%.随未来气候变化,红花龙胆适生区将呈现先减少后增加的变化趋势,在RCP 8.5情景下,至2070s阶段,西南地区红花龙胆适宜生境总面积与当前气候条件相比减少15.0%,但云南境内适生区和高适生区面积较当前分别增加32.8%和32.7%.红花龙胆适宜生长于温暖、湿润的气候条件下,气候变暖明显影响着适宜生境的面积和范围,尤其低海拔分布区对气候变化较敏感,适宜生境退缩严重,而高海拔地区由于降水、温度条件的改善适宜生境有所增加.随着全球气候的变化,未来西南地区红花龙胆主要分布区可能向西迁移,并向更高海拔扩张.

Based on 230 presence point records and 33 climatic variables, the potential distribution of C, entiana rhodantha during the Mid Holocene （about 6000 years ago）, current （1950-2000） and future （2050s and 2070s） was simulated using the MaxEnt model. The main climatic factors af- fecting Gentiana rhodantha distribution were screened by multivariate statistical analysis and ArcGIS spatial analysis to investigate the sensitivity of different distribution areas to climate change. The are- as under the curve indexes （AUC） of training data and test data were 0.942 and 0.849, respective- ly, which indicated the prediction accuracy was high. Five climatic factors, namely, the monthly average maximum temperature in July, the minimum temperature in June, July and August, and isothermality, showed most contribution to the MaxEnt model （cumulatively 59.9%）. Area of suit- able habitats retreated first and then expanded with climate change in the future. Up to 2070s, the total area of suitable habitats would decrease by 15.0% under RCP 8.5 compared with the current distribution, but areas of suitable habitats and highly suitable habitats in Yunnan would increase by 32.8% and 32.7%, respectively. The warm and moist climate was suitable for G. rhodarttha growth. Lower-altitude regions were more tion of suitable habitat areas. The sensitive to climate change areas of suitable habitats which resulted in the obvious reduc- high altitude region, however, wouldincrease with the improvement of temperature and precipitation condition. With the change of global climate, the main distribution area of G. rhodantha would be projected to migrate westward and expand to higher elevations.