Department of Biology, The Pennsylvania State University, University Park, Pennsylvania, United States of America.
PLoS One. 2011;6(6):e21725. doi: 10.1371/journal.pone.0021725. Epub 2011 Jun 29.
Global warming and shifted precipitation regimes increasingly affect species abundances and distributions worldwide. Despite a large literature on species' physiological, phenological, growth, and reproductive responses to such climate change, dispersal is rarely examined. Our study aims to test whether the dispersal ability of a non-native, wind-dispersed plant species is affected by climate change, and to quantify the ramifications for future invasion spread rates.
METHODOLOGY/PRINCIPAL FINDINGS: We experimentally increased temperature and precipitation in a two-cohort, factorial field study (n = 80). We found an overwhelming warming effect on plant life history: warming not only improved emergence, survival, and reproduction of the thistle Carduus nutans, but also elevated plant height, which increased seed dispersal distances. Using spatial population models, we demonstrate that these empirical warming effects on demographic vital rates, and dispersal parameters, greatly exacerbate spatial spread. Predicted levels of elevated winter precipitation decreased seed production per capitulum, but this only slightly offset the warming effect on spread. Using a spread rate decomposition technique (c*-LTRE), we also found that plant height-mediated changes in dispersal contribute most to increased spread rate under climate change.
CONCLUSIONS/SIGNIFICANCE: We found that both dispersal and spread of this wind-dispersed plant species were strongly impacted by climate change. Dispersal responses to climate change can improve, or diminish, a species' ability to track climate change spatially, and should not be overlooked. Methods that combine both demographic and dispersal responses thus will be an invaluable complement to projections of suitable habitat under climate change.
全球变暖以及降水格局的转变正日益影响全球物种的数量和分布。尽管有大量文献研究了物种对气候变化的生理、物候、生长和繁殖反应，但对扩散的研究却很少。我们的研究旨在检验一种非本地、风播植物物种的扩散能力是否受到气候变化的影响，并量化其对未来入侵扩散速度的影响。
方法/主要发现：我们在一个两批、双因素的野外实验中（n=80），对温度和降水进行了实验性增加。我们发现，升温对植物的生活史有压倒性的影响：升温不仅提高了蓟 Carduus nutans 的出芽率、存活率和繁殖率，还提高了植物的高度，从而增加了种子的扩散距离。通过空间种群模型，我们证明了这些对人口关键率和扩散参数的经验性变暖效应极大地加剧了空间扩散。预测水平的冬季降水增加会降低每个头状花序的种子产量，但这仅略微抵消了升温对扩散的影响。使用扩散率分解技术（c*-LTRE），我们还发现，植物高度介导的扩散变化对气候变化下扩散率的增加贡献最大。
结论/意义：我们发现，这种风播植物物种的扩散和扩散都受到气候变化的强烈影响。对气候变化的扩散反应可以改善或削弱物种在空间上追踪气候变化的能力，因此不应被忽视。将人口和扩散反应相结合的方法将是预测气候变化下适宜栖息地的宝贵补充。
