Prevéy Janet S, Seastedt Timothy R
Swiss Federal Institute for Forest, Snow and Landscape Research, Flüelastrasse 11, 7260, Davos Dorf, Switzerland.
Department of Ecology and Evolutionary Biology, University of Colorado, UCB 450, Boulder, 80309, CO, USA.
Oecologia. 2015 Nov;179(3):765-75. doi: 10.1007/s00442-015-3398-z. Epub 2015 Jul 31.
Shifting precipitation patterns resulting from global climate change will influence the success of invasive plant species. In the Front Range of Colorado, Bromus tectorum (cheatgrass) and other non-native winter annuals have invaded grassland communities and are becoming more abundant. As the global climate warms, more precipitation may fall as rain rather than snow in winter, and an increase in winter rain could benefit early-growing winter annuals, such as B. tectorum, to the detriment of native species. In this study we measured the effects of simulated changes in seasonal precipitation and presence of other plant species on population growth of B. tectorum in a grassland ecosystem near Boulder, Colorado, USA. We also performed elasticity analyses to identify life transitions that were most sensitive to precipitation differences. In both study years, population growth rates were highest for B. tectorum growing in treatments receiving supplemental winter precipitation and lowest for those receiving the summer drought treatment. Survival of seedlings to flowering and seed production contributed most to population growth in all treatments. Biomass of neighboring native plants was positively correlated with reduced population growth rates of B. tectorum. However, exotic plant biomass had no effect on population growth rates. This study demonstrates how interacting effects of climate change and presence of native plants can influence the population growth of an invasive species. Overall, our results suggest that B. tectorum will become more invasive in grasslands if the seasonality of precipitation shifts towards wetter winters and allows B. tectorum to grow when competition from native species is low.
全球气候变化导致的降水模式变化将影响入侵植物物种的成功入侵。在科罗拉多州的前缘山脉，雀麦（ cheatgrass）和其他非本地冬季一年生植物已经侵入草原群落，并且数量越来越多。随着全球气候变暖，冬季可能会有更多降水以降雨而非降雪的形式出现，冬季降雨增加可能会有利于像雀麦这样早期生长的冬季一年生植物，从而对本地物种造成损害。在本研究中，我们在美国科罗拉多州博尔德附近的一个草原生态系统中，测量了季节性降水模拟变化以及其他植物物种的存在对雀麦种群增长的影响。我们还进行了弹性分析，以确定对降水差异最敏感的生命阶段。在两个研究年份中，在接受冬季补充降水处理的条件下生长的雀麦种群增长率最高，而在接受夏季干旱处理的条件下生长的雀麦种群增长率最低。在所有处理中，幼苗存活到开花以及种子生产对种群增长的贡献最大。邻近本地植物的生物量与雀麦种群增长率降低呈正相关。然而，外来植物生物量对种群增长率没有影响。这项研究证明了气候变化和本地植物的存在之间的相互作用如何影响入侵物种的种群增长。总体而言，我们的结果表明，如果降水季节性向更湿润的冬季转变，并且在本地物种竞争较低时允许雀麦生长，那么雀麦在草原上将变得更具入侵性。
