基于Maxent模型的丹霞山国家级自然保护区极小种群植物丹霞梧桐的潜在生境评价

【目的】基于Maxent模型评价丹霞梧桐的潜在生境,为该种的就地保护和迁地保护提供科学依据。【方法】采用无人机获取丹霞梧桐黄叶期186个空间分布数据,结合6个环境变量,利用Maxent模型预测丹霞梧桐的潜在适生区,并分析主要环境变量对其分布的影响。【结果】Maxent模型评价效果达到优秀水平,训练集和验证集的AUC值分别为0.947和0.906;刀切法验证结果表明,高程、坡度和坡向是影响丹霞梧桐潜在分布的主要环境变量,其贡献率分别为51.2%、30.3%和7.8%;在3个主要环境变量的共同作用下,丹霞梧桐的潜在适生区主要分布在丹霞山高程150~530m、坡度20°~60°的阳坡;以自然断点法将丹霞梧桐的潜在适生区分为高适生区、中适生区、低适生区和非适生区4个等级,高、中适生区面积为30.27km^2,仅占丹霞山总面积的10.41%;低适生区面积为41.01km^2,非适生区面积为219.5km^2,共占丹霞山总面积的89.59%;野外实地调查数据验证结果表明,92.1%的丹霞梧桐实地分布点落入高、中适生区,Kappa系数为0.958,说明Maxent模型的预测精度较高。【结论】Maxent模型可较准确预测出丹霞梧桐在丹霞山的潜在适生区,并揭示影响其分布的3个主要环境变量,该模型对小尺度区域预测亦有较好效果。对丹霞梧桐保护提出2点建议:1)就地保护方面,要严格限制其高、中适生区的旅游设施建设,并建立长期的无人机遥感监测系统跟踪其种群动态变化;2)迁地保护方面,根据其适生条件,选择适合区域开展野外回归试验扩大其种群分布。本研究结果可验证低空无人机遥感在物种识别和种群调查中的优势和可行性,并揭示该方法在丹霞地貌这种特殊生境监测与评价中的潜力和应用价值。

Assessment of Potential Habitat for Firmiana danxiaensis,a Plant Species with Extremely Small Populations in Danxiashan National Nature Reserve Based on Maxent Model

【Objective】The Maxent model was used to evaluate the potential habitat of Firmiana danxiaensis in order to provide a scientific basis for in situ and ex situ conservation.【Method】A total of 186 distribution points data of F.danxiaensis in the yellow leaf stage were obtained by unmanned aerial vehicle(UAV).Combined with six environmental variables,the Maxent model was used to predict the potential suitable area of F.danxiaensis,and the impact of main environmental variables on its distribution was analyzed.【Result】The AUC values of the training set and the testing set were 0.947 and 0.906,respectively.The result of Jackknife test indicated that DEM,slope and aspect were the main environmental variables affecting the potential distribution of F.danxiaensis,contributing 51.2%,30.3%and 7.8%,respectively.Under the joint influence of the three main environmental variables,F.danxiaensis was mainly distributed on the sunny slopes with an elevation of 150-530 m and a slope of 20°-60°in Danxiasha national nature reserve.The potential suitable habitat was divided into four grades:highly suitable,moderately suitable,less suitable and unsuitable by natural break method.The total area of high and moderate suitable area of F.danxiaensis was 30.27 km^2,accounting for only about 10.41%of the total area under study.The less suitable area was 41.01 km^2,and the unsuitable area was 219.5 km^2,accounting for 89.59%of the total area.The field survey data verified that 92.1%of field distribution points of F.danxiaensis fell into high and moderately suitable area,and the kappa coefficient was 0.958,indicating that the prediction accuracy of Maxent model was high.【Conclusion】The Maxent model can accurately predict the potential suitable habitat of F.danxiaensis in Danxiashan national nature reserve,and revealed the three main environmental variables that affected its distribution,indicating that the model has a good effect on small-scale regional prediction.Two suggestions were put forward for the protection of F.danxiaensis:1)in terms of in situ conservation,it is necessary to strictly restrict the construction of tourist facilities in the highly and moderately suitable areas,and establish a long-term UAV remote sensing monitoring system to track the dynamic changes of the population;2)in terms of ex situ conservation,reintroduction experiments should be carried out as soon as possible to expand their population distribution according to their suitable area.This study also verified the advantage and feasibility of low-altitude UAV remote sensing in species identification and population surveys,and revealed its potential application in the monitoring and evaluation of Danxia landform.