Department of Biology, Western Washington University, 516 High St., Bellingham, WA, 98225, USA.
Am J Bot. 2018 Apr;105(4):760-778. doi: 10.1002/ajb2.1042. Epub 2018 Apr 6.
The unique geography of the Olympic Peninsula in Washington State, USA has promoted a flora with exceptional endemism that may face high rates of extinction due to climate change. The Olympic Mountains provide an unparalleled opportunity to test predicted responses in topographically complex environments and inform conservation plans for threatened alpine taxa.
We estimated the potential impact of climate change for five endemic alpine plants of the Olympic Peninsula. We used Principal Components Analysis (PCA) to visualize changes in climate niche-space in the alpine zone and the exposure of the endemics to changing conditions. We then constructed climate and topographic-based Species Distribution Models (SDMs) to estimate changes in the distribution of habitat for each taxon.
The Olympic alpine zone will experience novel environmental conditions in the future, with a pronounced decrease in winter snow and an increase in growing-season moisture stress. When topography was taken into account, the losses were more dramatic than the impact of climate alone. Indeed, 85-99% of the suitable habitat will be lost for each of the five focal taxa by 2080, with thermal refugia remaining only on the highest peaks of the eastern Olympics.
The Olympic alpine endemics are stranded on ever-shrinking habitat islands. Within a few, isolated thermal refugia, the distribution of micro-topography may be a critical factor in determining long-term survival. The Olympic Mountains and their alpine taxa are a model system for endemics worldwide, illustrating the biogeographic characteristics that underpin vulnerability to climate change.
美国华盛顿奥林匹克半岛独特的地理位置孕育了具有特殊特有性的植物区系，由于气候变化，这些特有植物可能面临高灭绝率。奥林匹克山脉为在地形复杂的环境中测试预测响应提供了一个无与伦比的机会，并为受威胁的高山类群的保护计划提供了信息。
我们估计了奥林匹克半岛五种特有高山植物受气候变化的潜在影响。我们使用主成分分析（PCA）来直观地展示高山带气候生态位空间的变化，以及特有植物对变化条件的暴露情况。然后，我们构建了基于气候和地形的物种分布模型（SDM），以估计每个类群的栖息地分布的变化。
奥林匹克高山带未来将经历新的环境条件，冬季降雪明显减少，生长季节水分胁迫增加。当考虑地形时，损失比气候单独影响更为显著。事实上，到 2080 年，五种焦点类群的适宜栖息地将有 85-99%丧失，而只有东部奥林匹克山脉的最高峰才会有热避难所。
奥林匹克高山特有植物被困在不断缩小的栖息地岛屿上。在少数孤立的热避难所中，微地形的分布可能是决定长期生存的关键因素。奥林匹克山脉及其高山类群是全球特有种的一个模式系统，说明了支持对气候变化脆弱性的生物地理特征。
