Species interactions across trophic levels mediate rainfall effects on dryland vegetation dynamics
Species interactions across trophic levels mediate rainfall effects on dryland vegetation dynamics
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DOI：
10.1002/ecm.1441
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发表时间：
2021-02-01
影响因子：
6.1
通讯作者：
Kelt, Douglas A.
中科院分区：
文献类型：
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作者：
Farias, Ariel A.;Armas, Cristina;Kelt, Douglas A.
干旱生态系统受到水资源的严重限制，降水在干旱地区所有物种的动态以及那里发生的生态系统过程中发挥着重要作用。然而，对生物相互作用如何调节旱地生态系统对降雨的长期反应的理解仍然非常零散。我们报告了一个独特的大型实地实验，跨越25年和三个营养水平（植物，小型哺乳动物食草动物，捕食者）在旱地生态系统中的北方智利地中海地区，我们评估了生物相互作用如何影响长期的植物群落对降水的反应。由于旱地系统中最持久的生态变化可能来自多年生植被的结构、覆盖和组成的变化，我们在分析中强调了多年生植物自下而上和自上而下控制之间的相互作用。降雨量是影响植物和小型哺乳动物动态及其相互作用的主要因素。短暂的植物覆盖动态密切跟踪短期年降雨量，但似乎不受自上而下的控制（食草动物）。与此相反，多年生植被对降水的响应是由（1）微妙的自上而下（食草动物）控制之间的复杂相互作用，在长期变得更加明显，（2）在潮湿的年份与短命植物的竞争，以及（3）捕食者对亚优势灌木和多年生草本植物的间接影响。这个长期的实地实验突出了气候引起的响应干旱多年生植被的影响，通过跨营养水平和时间尺度的相互作用。面对全球变化，了解多营养控制如何调节旱地植被对气候的反应，对于妥善管理干旱系统生物多样性的养护至关重要。
Arid ecosystems are strongly limited by water availability, and precipitation plays a major role in the dynamics of all species in arid regions, as well as the ecosystem processes that occur there. However, understanding how biotic interactions mediate long-term responses of dryland ecosystems to rainfall remains very fragmented. We report on a unique large-scale field experiment spanning 25 yr and three trophic levels (plants, small mammal herbivores, predators) in a dryland ecosystem in the northern Chilean Mediterranean Region where we assessed how biotic interactions influence the long-term plant community responses to precipitation. As the most persistent ecological changes in dryland systems may result from changes in the structure, cover, and composition of the perennial vegetation, we emphasized the interplay between bottom-up and top-down controls of perennial plants in our analyses. Rainfall was the primary factor affecting the dynamics of, and interactions among, plants and small mammals. Ephemeral plant cover dynamics closely tracked short-term annual rainfall, but seemed unaffected by top-down controls (herbivory). In contrast, the response of the perennial plant cover to precipitation was mediated by (1) a complex interplay between subtle top-down (herbivory) controls that become more apparent in the long-term, (2) competition with ephemeral plants during wet years, and (3) an indirect effect of predators on subdominant shrubs and perennial herbs. This long-term field experiment highlights how climate-induced responses of arid perennial vegetation are influenced by interactions across trophic levels and temporal scales. In the face of global change, understanding how multi-trophic controls mediate dryland vegetation responses to climate is essential to properly managing the conservation of biodiversity in arid systems.