Estación Experimental de Zonas Áridas, Consejo Superior de Investigaciones Científicas, Carretera de Sacramento s/n, E-04120, La Cañada, Almería, Spain.
Southeast Asia Rainforest Research Partnership, Danum Valley Field Centre, PO Box 60282, 91112, Lahad Datu, Sabah, Malaysia.
Nat Ecol Evol. 2017 Nov;1(11):1643-1648. doi: 10.1038/s41559-017-0326-0. Epub 2017 Sep 25.
Occasional periods of drought are typical of most tropical forests, but climate change is increasing drought frequency and intensity in many areas across the globe, threatening the structure and function of these ecosystems. The effects of intermittent drought on tropical tree communities remain poorly understood and the potential impacts of intensified drought under future climatic conditions are even less well known. The response of forests to altered precipitation will be determined by the tolerances of different species to reduced water availability and the interactions among plants that alleviate or exacerbate the effects of drought. Here, we report the response of experimental monocultures and mixtures of tropical trees to simulated drought, which reveals a fundamental shift in the nature of interactions among species. Weaker competition for water in diverse communities allowed seedlings to maintain growth under drought while more intense competition among conspecifics inhibited growth under the same conditions. These results show that reduced competition for water among species in mixtures mediates community resistance to drought. The delayed onset of competition for water among species in more diverse neighbourhoods during drought has potential implications for the coexistence of species in tropical forests and the resilience of these systems to climate change.
大多数热带森林偶尔会出现干旱期，但气候变化正在增加许多地区的干旱频率和强度，威胁到这些生态系统的结构和功能。间歇性干旱对热带树木群落的影响仍知之甚少，未来气候条件下干旱加剧的潜在影响则知之更少。森林对降水变化的反应将取决于不同物种对水分减少的耐受性以及植物之间的相互作用，这些相互作用可以减轻或加剧干旱的影响。在这里，我们报告了实验性的热带树木单一种群和混交林对模拟干旱的反应，这揭示了物种间相互作用性质的根本转变。在多样化的群落中，对水的竞争较弱，使幼苗能够在干旱条件下维持生长，而在同种植物之间，竞争加剧则抑制了生长。这些结果表明，在混合物中，物种间对水的竞争减少，调节了群落对干旱的抵抗力。在干旱期间，更多样化的生境中物种间对水的竞争延迟出现，这对热带森林中物种的共存和这些系统对气候变化的恢复力具有潜在影响。
