Ecology, Evolution, and Environmental Sciences Department, Columbia University, New York, NY 10027;
Institute of the Environment and Sustainability, University of California, Los Angeles, CA 90095.
Proc Natl Acad Sci U S A. 2017 Mar 28;114(13):3463-3468. doi: 10.1073/pnas.1608357114. Epub 2017 Mar 13.
Observational studies and experimental evidence agree that rising global temperatures have altered plant phenology-the timing of life events, such as flowering, germination, and leaf-out. Other large-scale global environmental changes, such as nitrogen deposition and altered precipitation regimes, have also been linked to changes in flowering times. Despite our increased understanding of how abiotic factors influence plant phenology, we know very little about how biotic interactions can affect flowering times, a significant knowledge gap given ongoing human-caused alteration of biodiversity and plant community structure at the global scale. We experimentally manipulated plant diversity in a California serpentine grassland and found that many plant species flowered earlier in response to reductions in diversity, with peak flowering date advancing an average of 0.6 days per species lost. These changes in phenology were mediated by the effects of plant diversity on soil surface temperature, available soil N, and soil moisture. Peak flowering dates were also more dispersed among species in high-diversity plots than expected based on monocultures. Our findings illustrate that shifts in plant species composition and diversity can alter the timing and distribution of flowering events, and that these changes to phenology are similar in magnitude to effects induced by climate change. Declining diversity could thus contribute to or exacerbate phenological changes attributed to rising global temperatures.
观察研究和实验证据都表明，全球气温上升已经改变了植物物候——生命事件（如开花、发芽和展叶）的时间。其他大规模的全球环境变化，如氮沉降和降水模式的改变，也与开花时间的变化有关。尽管我们越来越了解非生物因素如何影响植物物候，但我们对生物相互作用如何影响开花时间知之甚少，考虑到全球范围内正在进行的人为改变生物多样性和植物群落结构，这是一个显著的知识空白。我们在加利福尼亚蛇纹石草原上进行了植物多样性的实验性操纵，发现许多植物物种的开花时间因多样性的减少而提前，平均每个物种的花期提前了 0.6 天。这些物候变化是由植物多样性对土壤表面温度、可用土壤氮和土壤湿度的影响介导的。在高多样性的斑块中，开花高峰期的物种分布也比预期的单一种群更为分散。我们的研究结果表明，植物物种组成和多样性的变化可以改变开花事件的时间和分布，而且这些物候变化的幅度与气候变化引起的变化相似。因此，多样性的减少可能会导致或加剧归因于全球气温上升的物候变化。
