Department of Ecology, Evolution, and Behavior, University of Minnesota, St Paul, Minnesota 55108, USA.
Department of Entomology, University of Maryland, College Park, Maryland 20742, USA.
Nature. 2014 Apr 24;508(7497):517-20. doi: 10.1038/nature13144. Epub 2014 Mar 9.
Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.
人类对营养循环和食草动物群落的改变正在极大地影响着全球生物多样性。生态理论预测，这些变化应该是强烈的反作用：养分的增加会通过加剧对光的竞争导致植物物种的丧失，而食草动物通过增加地面光照来防止竞争排斥，特别是在高生产力的系统中。在这里，我们使用跨越全球相关条件范围的实验数据来检验这样一个假设，即由于食草作用而导致的草本植物物种的丧失可能会因光照增加而得到补偿。这个实验在 6 个大陆的 40 个草原上进行了复制，结果表明，养分和食草动物可以通过光限制作为相互抗衡的力量来控制当地的植物多样性，而不依赖于地点的生产力、土壤氮、食草动物的类型和气候。养分的增加通过光限制一致地降低了当地的多样性，而食草作用在减轻光限制的地方挽救了多样性。因此，在食草动物增加地面光照的草原上，由于人为富营养化导致的物种丧失可以得到缓解。
