气候变化对东北濒危动物驼鹿潜在生境的影响

气候变化是造成生物多样性下降和物种灭绝的主要因素之一。研究气候变化对物种生境,尤其是濒危物种生境影响对未来保护物种多样性和保持生态系统功能完整性具有重要意义。以驼鹿乌苏里亚种(Alces alces cameloides)为研究对象,选取了对驼鹿分布可能存在影响的22个环境因子,利用最大熵(Maxent)模型模拟了驼鹿基准气候条件下在我国东北的潜在生境分布,并预测了RCP4.5和RCP8.5两种气候变化情景下2041—2060年(2050s)、2061—2080年(2070s)驼鹿潜在分布,采用接收工作曲线下面积(AUC)对模型预测能力进行评估。研究结果表明:最大熵模型预测驼鹿潜在生境分布的精度较高(平均AUC值为0.845),22个环境因子中,年均温、最暖季均温、年降水、平均日较差是影响驼鹿生境分布的主要因子。基准气候条件下,驼鹿的潜在生境面积占研究区域总面积的36.4%,潜在生境分布区主要在大、小兴安岭。随着时间的推移,研究区内驼鹿当前潜在生境面积明显减少,而新增潜在生境面积较少,总面积呈现急剧减少的趋势,其中RCP8.5情景减少程度大于RCP4.5情景。至2050s阶段,当前潜在生境面积平均将减少62.3%,新增潜在分布面积平均仅为3.6%,总潜在生境面积最高将减少65.6%,平均将减少58.8%;至2070s阶段,当前潜在生境面积平均将减少75.8%,新增潜在分布面积平均仅为1.9%,总潜在生境面积最高将减少93.1%,平均减少73.9%。空间分布上,驼鹿的潜在生境的几何中心将先向西北移动,然后再向高纬度地区西南方向迁移,至2050s阶段,潜在分布生境的几何中心在RCP4.5和RCP8.5情景下的迁移距离分别为183.5 km和210.8 km;至2070s阶段,相应情景下的迁移距离将缩短至28.7 km和33.8 km。潜在生境分布整体呈现向高海拔、高纬度迁移的趋势。

Effects of climate change on the potential habitat of Alces alces cameloides, an endangered species in Northeastern China

Earth is undergoing an obvious global warming, which has attracted the attention of people and governments worldwide. In fact, global warming exerts a negative effect on people and various other species. Climate change greatly affects plant and animal growth; it is one of the main factors for the decline in biodiversity and species extinction. Therefore, it is important to study how climate affects species habitats, especially those of endangered species, to protect biodiversity and maintain the functional integrity of the ecosystem. We used the maximum entropy model (Maxent) and selected 22 different environmental factors that may influence the distribution of the moose (Alces alces cameloides) to simulate the distribution of its potential habitat in Northeastern China under the current climate conditions (1950-2000). The future potential habitats for the moose were also predicted in two periods, 2041-2060 and 2061-2080, under two climate change scenarios, RCP4.5 and RCP8.5. Furthermore, we evaluated the performance of this model by using the area under the curve (AUC) of the receiver operator characteristic curve. The results show that the prediction of Maxent is precise and acceptable (mean AUC=0.845). Among the 22 environmental factors, annual mean temperature, mean temperature of the warmest quarter, annual precipitation, and mean diurnal range have great influences on potential habitats for the moose. Under current climate conditions, 36.4% of the study area, mainly the Greater and Lesser Khingan Mountains, is a potential habitat for the moose. With climate change, the area of the potential habitat in the study area would decrease faster than the increase rate of a new potential habitat, resulting in a rapid decline in the area of the entire potential habitat. The decline in RCP8.5 climate scenarios is higher than that in RCP4.5 climate scenarios. By 2041-2060, the current potential distribution will reduce by 62.3%; the new potential distribution will increase by 3.6%; and the maximum total potential distribution will decrease by 65.6%, with an average decrease of 58.8%. By 2061-2080, the current potential distribution will decrease by 75.8%; the new potential distribution will increase by 1.9%; and the maximum total potential distribution will decrease by 93.1%, with an average decrease of 73.9%. In terms of spatial distribution of the potential habitat for the moose, the geometric center of the potential habitat will first move northwest, and then move southwest. By 2041-2060, the center of the potential habitat in RCP4.5 and RCP8.5 will shift by 183.5 km and 210.8 km, respectively; by 2061-2080, the corresponding distance will shrink to 28.7 km and 33.8 km, respectively. On the basis of these data, it can be safely concluded that the potential distribution of moose will generally shift to a region at a higher latitude and altitude. Therefore, measures for the protection of habitats for the moose in Northeastern China are urgently required.