Associational resistance to both insect and pathogen damage in mixed forests is modulated by tree neighbour identity and drought
Associational resistance to both insect and pathogen damage in mixed forests is modulated by tree neighbour identity and drought
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DOI：
10.1111/1365-2745.13397
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发表时间：
2020-05-14
影响因子：
5.5
通讯作者：
Hector, Andrew
中科院分区：
文献类型：
--
作者：
Field, Elsa;Castagneyrol, Bastien;Hector, Andrew
害虫和病原体之间的相互作用可能会导致树木健康下降，许多研究表明，与单一栽培相比，混交林中的害虫危害有所减少。然而，很少有作者同时考虑树木多样性对这两个群体的影响。此外，树木多样性对树木害虫和病原菌的影响是否对干旱等非生物条件的变化具有很强的适应性尚不清楚。在法国西南部的一个大型树木多样性实验中，我们研究了树木多样性对叶昆虫食草性疾病、橡树白粉病及其在不同水分条件下的相互作用。使用一种缓解干旱条件的灌溉处理，我们能够通过实验评估在不同的非生物环境下树木多样性的影响。我们沿着丰富度梯度从1到4个树种对样地进行了调查，其中一个重点研究树种(Quercus Robur)与其他橡树树种(Q.pyrenaica和Q.ilex)和一个较高的阔叶树种(桦树)混合。树种丰富度的增加降低了潜叶虫的丰富度，叶片咀嚼损伤和橡树白粉病感染，这与资源稀释的保护作用是一致的。然而，灌溉对潜叶虫的丰富度效应比非灌溉区强，这表明环境条件可以调节多样性效应。除了树种丰富度的影响外，地块中白桦树的存在增加了叶片咀嚼虫和白粉病的危害，但降低了叶潜蝇的危害，这表明额外的树木邻居身份效应可能与小气候的调节有关。我们发现潜叶蛾的丰度与橡树白粉病呈负相关，这与橡树伤害剂之间的拮抗作用是一致的。总体而言，我们的研究说明了在设计更耐虫害和病原体破坏的森林时，同时考虑树木多样性和组成(邻居身份)的重要性。
Tree health declines can be caused by interactions between pests and pathogens and many studies have shown a reduction in their damage in mixed species forests compared to monocultures. Yet few authors have considered tree diversity effects on both groups simultaneously. Moreover, it is unclear whether diversity effects on tree pests and pathogens are robust to changes in abiotic conditions, such as drought.We addressed tree diversity effects on foliar insect herbivory, oak powdery mildew and their interaction under contrasting water regimes in a large-scale tree diversity experiment in SW France. Using an irrigation treatment that alleviated drought conditions, we were able to experimentally assess the effects of tree diversity under contrasting abiotic environments. We surveyed plots along a richness gradient from one to four tree species, in which a focal study species of oak (Quercus robur) was mixed with other oak species (Q. pyrenaica and Q. ilex) and a taller, broadleaved species (Betula pendula).Increasing tree species richness lowered leaf miner abundance, leaf chewer damage and oak powdery mildew infection, consistent with a protective effect of resource dilution. However, richness effects on leaf miners were stronger in irrigated compared to non-irrigated blocks, indicating that environmental conditions can modulate diversity effects. Separate from the effect of tree species richness, the presence of birch in a plot increased damage by leaf chewers and powdery mildew, but lowered leaf miner damage, suggesting additional tree neighbour identity effects potentially linked to modulation of microclimate. We found a negative association between leaf miner abundance and oak powdery mildew, consistent with antagonism between oak damage agents.Synthesis. Overall, our study illustrates the importance of considering both tree diversity and composition (neighbour identity) in designing forests more resistant to pest and pathogen damage.