Continental-Scale Assessment of Risk to the Australian Odonata from Climate Change

Climate change is expected to have substantial impacts on the composition of freshwater communities, and many species are threatened by the loss of climatically suitable habitat. In this study we identify Australian Odonata (dragonflies and damselflies) vulnerable to the effects of climate change on the basis of exposure, sensitivity and pressure to disperse in the future. We used an ensemble of species distribution models to predict the distribution of 270 (85%) species of Australian Odonata, continent-wide at the subcatchment scale, and for both current and future climates using two emissions scenarios each for 2055 and 2085. Exposure was scored according to the departure of temperature, precipitation and hydrology from current conditions. Sensitivity accounted for change in the area and suitability of projected climatic habitat, and pressure to disperse combined measurements of average habitat shifts and the loss experienced with lower dispersal rates. Streams and rivers important to future conservation efforts were identified based on the sensitivity-weighted sum of habitat suitability for the most vulnerable species. The overall extent of suitable habitat declined for 56–69% of the species modelled by 2085 depending on emissions scenario. The proportion of species at risk across all components (exposure, sensitivity, pressure to disperse) varied between 7 and 17% from 2055 to 2085 and a further 3–17% of species were also projected to be at high risk due to declines that did not require range shifts. If dispersal to Tasmania was limited, many south-eastern species are at significantly increased risk. Conservation efforts will need to focus on creating and preserving freshwater refugia as part of a broader conservation strategy that improves connectivity and promotes adaptive range shifts. The significant predicted shifts in suitable habitat could potentially exceed the dispersal capacity of Odonata and highlights the challenge faced by other freshwater species.

气候变化预计将对淡水生物群落的组成产生显著影响，诸多物种正面临因气候适宜栖息地丧失而带来的生存威胁。本研究基于未来暴露程度、敏感性与扩散压力三个维度，筛选出易受气候变化影响的澳大利亚蜻蛉目（Odonata，即蜻蜓与豆娘）物种。本研究采用集成物种分布模型，对270种（占澳大利亚蜻蛉目物种总数的85%）物种的分布展开预测：预测范围覆盖澳洲大陆全域，分辨率为子流域尺度；同时分别基于当前气候与未来气候情景进行预测，未来气候情景包含2055年与2085年两个时间节点，各设置两种排放场景。暴露度依据温度、降水与水文条件相较于当前状态的偏离程度进行评分。敏感性指标考量预测所得气候栖息地的面积与适宜性变化，扩散压力则综合平均栖息地偏移量与低扩散速率下的栖息地损失量进行测算。研究基于最易受威胁物种的栖息地适宜性敏感性加权总和，识别出对未来保护工作具有重要意义的溪流与河流生态系统。至2085年，根据不同排放场景，56%至69%的建模物种的适宜栖息地总面积将出现缩减。2055年至2085年间，同时满足暴露、敏感性与扩散压力三个风险维度的物种占比介于7%至17%之间；另有3%至17%的物种因无需进行分布范围迁移的栖息地缩减而被预测为高风险物种。若向塔斯马尼亚岛的扩散受到限制，诸多东南部分布的物种将面临显著升高的生存风险。保护工作需将创建与保护淡水避难所作为核心内容，纳入提升栖息地连通性、促进适应性分布范围迁移的整体保护策略之中。预测得到的适宜栖息地显著偏移量或超出蜻蛉目的扩散能力，这也凸显了其他淡水物种所面临的生存挑战。