CIDE-CSIC, Montcada, Valencia, Spain.
School of Life Sciences, University of Sussex, Brighton, UK.
Ann Bot. 2018 Nov 30;122(6):961-971. doi: 10.1093/aob/mcy122.
Assessing the resilience of plant-animal interactions is critical to understanding how plant communities respond to habitat disturbances. Most ecosystems experience some level of natural disturbance (e.g. wildfires) to which many organisms are adapted. Wildfires have structured biotic communities for millennia; however, the effects of fire on interactions such as pollination have only recently received attention. A few studies have shown that generalist plants can buffer the impact of fires by pollinator replacement, suggesting that the resilience to disturbance could depend on the level of specialization of the interactions. Here, we hypothesize that (1) fires could impose negative effects on plants with specialized pollination systems, and (2) in large wildfires, these negative effects will be stronger with increasing distance inside the burnt area because pollinators will need more time to recolonize.
These questions were tested in the specialized pollination system of a widespread Mediterranean palm, Chamaerops humilis. The post-fire pollination resilience was assessed in replicated wildfires representing three post-fire ages by measuring the abundance of beetle pollinators and by estimating fruit set (i.e. the proportion of flowers setting fruits) in burnt and unburnt areas. To test for distance effects, plants were sampled along transects inside the burnt area.
Despite a marked post-fire decline in the specialist pollinator, exacerbated by the distance from the fire's edge, the palm's fruit set was barely affected. The temporary replacement by a sap beetle at burnt sites - an effective pollinator that had not been previously recognized - provided post-fire reproductive resilience.
Differential pollinator responses to disturbance can ensure plant success even in plants with only two functionally similar pollinators. This highlights the importance of pollinator replacement and dynamics for the resilience of interactions and ultimately of plant reproduction in disturbance-prone ecosystems.
评估动植物相互作用的恢复力对于理解植物群落如何应对生境干扰至关重要。大多数生态系统都会经历一定程度的自然干扰（例如野火），许多生物都适应了这种干扰。野火已经塑造了生物群落数千年；然而，火灾对授粉等相互作用的影响直到最近才受到关注。一些研究表明，一般植物可以通过传粉者的替代来缓冲火灾的影响，这表明对干扰的恢复力可能取决于相互作用的专业化程度。在这里，我们假设：（1）火灾可能对具有专门授粉系统的植物产生负面影响，（2）在大型野火中，随着离燃烧区域内部的距离增加，这些负面影响将更强，因为传粉者需要更多的时间来重新定殖。
这些问题是在广泛分布于地中海的一种棕榈植物 Chamaerops humilis 的专门授粉系统中进行测试的。通过测量甲虫传粉者的丰度，并估计燃烧区和未燃烧区花朵的结实率（即花结实的比例），来评估火灾后授粉的恢复力。为了测试距离效应，在燃烧区内部的样带上对植物进行了采样。
尽管专门的传粉者在火灾后明显减少，而且离火灾边缘越远，这种减少就越严重，但棕榈的结实率几乎没有受到影响。在燃烧地点，一种临时的树皮甲虫替代了传粉者——一种以前未被识别的有效传粉者——为火灾后的繁殖提供了恢复力。
对干扰的不同传粉者反应可以确保即使在只有两种功能相似的传粉者的植物中，植物也能成功繁殖。这突出了传粉者替代和动态对相互作用以及在易受干扰的生态系统中植物繁殖的恢复力的重要性。
