【作者】 高翔；

【导师】 梁婕； 刘湛；

【作者基本信息】 湖南大学 ， 环境工程（专业学位）， 2018， 硕士

【摘要】 气候变化会改变栖息地质量,间接影响到生物多样性。小白额雁作为一种濒危迁徙候鸟,对长江中下游生物多样性保护具有非常重要的意义。研究首先利用Maxent模型,结合2004-2015年小白额雁分布点和典型环境特征变量,分析了四种典型气候情景下小白额雁栖息地适宜性。研究结果显示,所有模型受试者工作特征曲线下面积值(AUC)都较高(现在和未来情景下AUC均高于0.8),显示了模型很高的预测能力。在所有环境变量中,最具影响力的变量是:荸荠、看麦娘等植物的丰度、年均温、最冷季均温和最冷月降水。适宜的小白额雁栖息地主要分布在长江中下游地区的湖南、东部区域,特别是湖南省的东洞庭湖区域、安徽省的升金湖区域。Maxent模型的预测还解释了小白额雁在不同气候情景下的栖息地适宜性,在2070年(RCP 4.5气候排放条件下),小白额雁的适宜栖息地分布范围有明显萎缩趋势,适宜栖息地占研究区域总面积的比例从现在情景的5.10%降低到3.00%。基于现在气候及未来气候情景条件下,气候变化对小白额雁的栖息地适宜性影响非常大,因此气候变化的不确定性会影响到小白额雁的保护结果。通过运行Marxan对研究区域进行筛选,能够得到研究区域内每个规划单元的选择频率,并最终得出一系列理想的小白额雁保护区设立位置作为最优解。规划单元的选择频率表示一个规划单元的保护重要性,而最优解是一个理想的小白额雁保护区设置范围。研究表明,最优解中共有1104个规划单元,主要分布在湖南和长江三角洲区域。其中具有代表性的有:洞庭湖区域、升金湖区域以及鄱阳湖区域。在建立自然保护区时,将主要资金投入这些区域将提高小白额雁的保护效率。利用投资组合方法(MPT),可以得到研究区域的投资-风险效率曲线。该方法是将资源按不同比例分配在湖南、江西以及长江三角洲区域,根据投资-风险效率曲线,投资的风险和收益将完全不同。研究表明,如果将资金全部投入湖南区域,气候变化不确定性造成的风险将会达到最大值,同时保护收益也达到最大;如果将资金按一定比例分配在湖南、东部区域、江西三个区域,气候变化不确定性造成的风险将会最小,保护收益也较低。决策者可以根据实际情况对风险和收益进行权衡,选择合适的保护策略。本研究的方法有效的评价了小白额雁栖息地质量分布情况,并综合选出未来条件下性价比更高的投资区域和投资比例,可以作为长江中下游鸟类栖息地保护优化以及建立相应物种保护策略的参考。更多还原

【Abstract】 Climate change will change habitat quality and affect biodiversity indirectly.Lesser Whitefronted Goose,as an endangered migratory bird,is quite significant to biodiversity conservation in the middle and lower reaches of the Yangtze River.In this study,Maxent model was used to analyze the habitat suitability of the wild goose in four typical climate scenarios,combining with the distribution data and the typical environmental characteristics of the wild geese from 2004 to 2015.The results showed that: 1.The area value under the operating characteristic curve of all model subjects was high(AUC was higher than 0.8 in present and future scenarios,which showed that the model was highly predictive.)of all the environmental variables,the most influential variables were: habitat suitability index of Carex heterolepis,Alopecurus aequalis and Eleocharis migoana,average annual temperature,the coldest season mean temperature and the coldest monthly precipitation.The suitable habitat of the wild goose is mainly distributed in the middle and lower reaches of the Yangtze River in Hunan,the Yangtze River Delta region,especially in the East Dongting Lake region of Hunan Province.The prediction of the Maxent model of Shengjin Lake region in Anhui Province also explained the habitat suitability of the wild goose under different climate scenarios.In 2070,under the condition of RCP 4.5 climate emissions,the suitable habitat distribution range of the small white goose showed a significant shrinking trend.The average habitat suitability decreased from 5.1% to 3.00%.Based on the current climate and future climate scenarios,climate change has a great impact on the habitat suitability of wild geese.Therefore,the uncertainty of climate change will affect the conservation results of small white goose.Then,the suitable habitat of the wild goose was screened by running Marxan,and the selection frequency of each planning unit in the study area was obtained.A series of locations is obtained as the optimal solution.The selection frequency of the planning unit indicates the importance of the protection of a planning unit.The optimal solution is an ideal range for setting up a reserve for Lesser White-fronted Goose.The study shows that the optimal solution has 1104 planning units,mainly distributed in Hunan and the Yangtze River Delta region,among which the typical ones are: Dongting Lake region.The Shengjin Lake region and Poyang Lake region.In the establishment of nature reserves,the main funds invested in these areas will improve the conservation efficiency of the small white goose.Finally,by using the modern portfolio theory,the investment-risk efficiency curve of the studied region is obtained.The method is to distribute the resources in different proportions in Hunan,Jiangxi and the Yangtze River Delta region,according to the investment-risk efficiency curve.The risk and return of investment will be completely different.The study shows that if all the funds are invested in Hunan region,the risk caused by the uncertainty of climate change will reach the maximum,and the benefit of protection will also reach the maximum.If funds are allocated in proportion to the three regions of Hunan,the Yangtze River Delta,and Jiangxi,the risk of climate change uncertainty will be minimal,and the benefits of protection will be lower.Policymakers can weigh the risks and benefits according to the actual situation.Select the appropriate protection strategy.The method of this study was used to evaluate the habitat quality distribution of the Lesser White-fronted Goose,and to select a better investment area and investment ratio under the future conditions.It can be used as a reference for the optimization of bird habitat protection in the middle and lower reaches of the Yangtze River and the establishment of corresponding species protection strategies.更多还原