Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, Queensland, Australia.
Biol Rev Camb Philos Soc. 2019 Aug;94(4):1416-1429. doi: 10.1111/brv.12508. Epub 2019 Mar 18.
Woody climbers or, 'lianas', are one of the features that characterise rainforests. They contribute substantially to plant diversity and leaf biomass which makes them a potentially important food source for herbivores. Here, we focus on insect herbivores, folivores in particular, to show how disparities in the quantitative and qualitative availability of leaves between lianas and trees may differentially influence insect folivory and the herbivore communities themselves. We develop a conceptual model and show that lianas in general have lower structural and chemical defences, a greater nutritional profile and a preferable phenology in comparison with trees, which, contrary to our expectations, has led to assemblages of more-specialised insects. The impacts this has on higher trophic levels and broader ecological networks, however, are poorly known. We show through a study of four tropical floras from different biogeographic realms that lianas are likely to be a target for a wide range of insect herbivore taxa as they are a phylogenetically diverse group and increase diversity of higher taxa at local scales. This, in combination with their highly palatable leaves, may also make them a suitable temporary food source for insects during times when preferred host plants are scarce. This phenomenon has been observed in mammalian herbivores but awaits investigation in insects as does the effects this may have on survival and fitness. Apparent recent increases in liana abundances in some forests, likely due to climate change, makes understanding their role in supporting and maintaining biodiversity an increasingly important and necessary challenge. Since trees or saplings have usually been the subject of studies on insect herbivory, major knowledge gaps remain about the ways in which lianas contribute to, support and maintain the ecosystems in which they exist. We use our conceptual model to guide future research directions and express the necessity for caution when extrapolating explanations of herbivory derived from data on trees to growth forms with fundamentally different ecologies.
木质藤本植物，又称“藤本植物”，是热带雨林的特征之一。它们对植物多样性和叶生物量有很大的贡献，使它们成为食草动物潜在的重要食物来源。在这里，我们专注于昆虫食草动物，特别是食叶动物，以展示藤本植物和树木之间叶片在数量和质量上的可利用性差异如何可能对昆虫食叶和食草动物群落本身产生不同的影响。我们提出了一个概念模型，并表明藤本植物通常具有较低的结构和化学防御、更高的营养谱和更适宜的物候，与树木相反，这导致了更专业化的昆虫组合。然而，这种情况对更高营养级和更广泛的生态网络的影响知之甚少。我们通过对来自不同生物地理区系的四个热带植物群的研究表明，藤本植物很可能成为广泛的昆虫食草动物类群的目标，因为它们是一个系统发育多样化的群体，并在局部尺度上增加了高等分类群的多样性。这一点，再加上它们非常可口的叶子，也可能使它们成为昆虫在缺乏首选宿主植物时的临时合适食物来源。这种现象在哺乳动物食草动物中已经观察到，但在昆虫中还需要研究，也需要研究这种现象对生存和适应能力的影响。一些森林中藤本植物的丰度最近明显增加，可能是由于气候变化所致，因此，了解它们在支持和维持生物多样性方面的作用越来越成为一个重要和必要的挑战。由于树木或幼树通常是昆虫食草性研究的对象，因此，关于藤本植物如何为它们所存在的生态系统做出贡献、支持和维持生态系统的方法，仍然存在很大的知识差距。我们使用我们的概念模型来指导未来的研究方向，并表达在将从树木数据得出的食草动物解释外推到具有根本不同生态的生长形式时需要谨慎。
