Ferlian Olga, Lintzel Esther-Marie, Bruelheide Helge, Guerra Carlos A, Heklau Heike, Jurburg Stephanie, Kühn Paul, Martinez-Medina Ainhoa, Unsicker Sybille B, Eisenhauer Nico, Schädler Martin
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103 Leipzig, Germany.
Institute of Biology, Leipzig University, Deutscher Platz 5e, 04103 Leipzig, Germany.
Basic Appl Ecol. 2021 Sep;55:110-123. doi: 10.1016/j.baae.2020.09.009. Epub 2020 Sep 28.
Research aimed at understanding the mechanisms underlying the relationship between tree diversity and antagonist infestation is often neglecting resource-use complementarity among plant species. We investigated the effects of tree species identity, species richness, and mycorrhizal type on leaf herbivory and pathogen infestation. We used a tree sapling experiment manipulating the two most common mycorrhizal types, arbuscular mycorrhiza and ectomycorrhiza, via respective tree species in monocultures and two-species mixtures. We visually assessed leaf herbivory and pathogen infestation rates, and measured concentrations of a suite of plant metabolites (amino acids, sugars, and phenolics), leaf elemental concentrations (carbon, nitrogen, and phosphorus), and tree biomass. Tree species and mycorrhizal richness had no significant effect on herbivory and pathogen infestation, whereas species identity and mycorrhizal type had. Damage rates were higher in arbuscular mycorrhizal (AM) than in ectomycorrhizal (EM) trees. Our structural equation model (SEM) indicated that elemental, but not metabolite concentrations, determined herbivory and pathogen infestation, suggesting that the investigated chemical defence strategies may not have been involved in the effects found in our study with tree saplings. Other chemical and physical defence strategies as well as species identity as its determinant may have played a more crucial role in the studied saplings. Furthermore, the SEM indicated a direct positive effect of AM trees on herbivory rates, suggesting that other dominant mechanisms, not considered here, were involved as well. We found differences in the attribution of elemental concentrations between the two rates. This points to the fact that herbivory and pathogen infestation are driven by distinct mechanisms. Our study highlights the importance of biotic contexts for understanding the mechanisms underlying the effects of biodiversity on tree-antagonist interactions.
旨在理解树木多样性与害虫侵害之间关系背后机制的研究，常常忽略了植物物种间的资源利用互补性。我们调查了树种身份、物种丰富度和菌根类型对叶片食草动物侵害和病原体侵染的影响。我们进行了一项树苗实验，通过单一栽培和两种树种混合栽培中各自的树种，操纵两种最常见的菌根类型，即丛枝菌根和外生菌根。我们直观地评估了叶片食草动物侵害率和病原体侵染率，并测量了一系列植物代谢物（氨基酸、糖类和酚类）的浓度、叶片元素浓度（碳、氮和磷）以及树木生物量。树种和菌根丰富度对食草动物侵害和病原体侵染没有显著影响，而树种身份和菌根类型有显著影响。丛枝菌根（AM）树木的损害率高于外生菌根（EM）树木。我们的结构方程模型（SEM）表明，是元素浓度而非代谢物浓度决定了食草动物侵害和病原体侵染，这表明在我们对树苗的研究中发现的影响可能并未涉及所研究的化学防御策略。其他化学和物理防御策略以及作为其决定因素的树种身份可能在被研究的树苗中发挥了更关键的作用。此外，结构方程模型表明AM树木对食草动物侵害率有直接的正向影响，这表明还涉及了此处未考虑的其他主要机制。我们发现两种比率在元素浓度归因方面存在差异。这表明食草动物侵害和病原体侵染是由不同机制驱动的。我们的研究强调了生物背景对于理解生物多样性对树木与害虫相互作用影响背后机制的重要性。
