Ambient changes exceed treatment effects on plant species abundance in global change experiments
Ambient changes exceed treatment effects on plant species abundance in global change experiments
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DOI：
10.1111/gcb.14442
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发表时间：
2018-12-01
影响因子：
11.6
通讯作者：
Tilman, David
中科院分区：
文献类型：
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作者：
Langley, J. Adam;Chapman, Samantha K.;Tilman, David
物种对环境变化的反应将决定未来的群落组成和生态系统功能。许多合成的全球变化实验研究治疗效果大小的幅度，但我们缺乏了解植物对治疗的反应相比，在未操纵的（环境或背景）系统正在发生的变化。我们使用了一个数据库的长期全球变化研究操纵CO2，营养物质，水，和温度来回答三个问题：（a）如何在植物物种丰富度的变化在周围的地块与那些在处理地块？(b)物种水平丰度随时间的环境变化幅度如何与对全球变化处理的反应有关？(c)物种水平对全球变化处理的反应方向与环境变化的方向不同吗？我们估计了16个长期全球变化实验中791种植物物种在环境和处理地块中的植物丰度的时间趋势，产生了2,116个实验物种处理组合。令人惊讶的是，对于大多数物种（57%），环境变化的幅度大于治疗效果的幅度。然而，环境变化的方向，无论一个物种是增加或减少在环境条件下的丰度，没有对治疗效果的方向。虽然周围的群落具有内在的动态性，但现在有广泛的证据表明，人为驱动因素正在定向改变许多生态系统中的植物群落。因此，全球变化的处理效果必须在植物物种的轨迹，可能是由持续的环境变化驱动的背景下进行解释。
The responses of species to environmental changes will determine future community composition and ecosystem function. Many syntheses of global change experiments examine the magnitude of treatment effect sizes, but we lack an understanding of how plant responses to treatments compare to ongoing changes in the unmanipulated (ambient or background) system. We used a database of long-term global change studies manipulating CO2, nutrients, water, and temperature to answer three questions: (a) How do changes in plant species abundance in ambient plots relate to those in treated plots? (b) How does the magnitude of ambient change in species-level abundance over time relate to responsiveness to global change treatments? (c) Does the direction of species-level responses to global change treatments differ from the direction of ambient change? We estimated temporal trends in plant abundance for 791 plant species in ambient and treated plots across 16 long-term global change experiments yielding 2,116 experiment-species-treatment combinations. Surprisingly, for most species (57%) the magnitude of ambient change was greater than the magnitude of treatment effects. However, the direction of ambient change, whether a species was increasing or decreasing in abundance under ambient conditions, had no bearing on the direction of treatment effects. Although ambient communities are inherently dynamic, there is now widespread evidence that anthropogenic drivers are directionally altering plant communities in many ecosystems. Thus, global change treatment effects must be interpreted in the context of plant species trajectories that are likely driven by ongoing environmental changes.