Evaluating a trait-based approach to compare natural enemy and pest communities in agroforestry vs. arable systems.
Evaluating a trait-based approach to compare natural enemy and pest communities in agroforestry vs. arable systems.
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DOI：
10.1002/eap.2294
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发表时间：
2020-10
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通讯作者：
Tom Staton;R. Walters;Jo U. Smith;T. Breeze;R. D. Girling
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作者：
Tom Staton;R. Walters;Jo U. Smith;T. Breeze;R. D. Girling
多样化的耕作系统，例如那些结合农林要素的耕作系统，已被提议作为一种能够维持和改善多种生态系统服务的解决办法。然而，耕地内外生境多样化对农作物无脊椎害虫及其天敌的影响是复杂而不一致的。这妨碍了制定政策建议，以促进采用这种管理战略来提供自然虫害防治服务。本研究首次采用基于性状的方法研究了不同耕作制度对植物、无脊椎草食动物和无脊椎天敌群落的影响。然后，我们通过将结果与使用传统分类学方法生成的结果进行比较来评估这种方法。在三个工作农场中的每一个，我们在一个农林复合田（一个多样化的农业系统，包括由树行隔开的可耕地作物的小巷）和一个成对的非多样化农场区域（可耕地对照田）内取样。96个采样点每个采样8 - 10次，得到344个分类类群的393318个无脊椎动物标本。与耕地对照区相比，无脊椎动物的食性特化、花期短、花期晚、植物的匍匐习性和多年生特征与农林复合作物林巷的相关性更强。我们假设这是由于农林复合系统中栖息地干扰减少和栖息地复杂性增加的结果。与对照耕地相比，农林业作物林道的分类丰富度和多样性更高，但在低营养水平上这种效应更强。然而，农林复合作物干旱区天敌功能性状多样性显著高于耕地对照区，表明农林复合作物干旱区的生物防治水平有所提高，这是传统多样性指标无法检测到的。8个主要害虫类群中，3个在农林复合系统中被显著抑制，2个相对于耕地控制区更为丰富。基于性状的方法可以更好地了解耕作制度对害虫及其天敌的影响，因此我们建议在未来多样化耕作制度的研究中应用和试验。
Diversified farming systems, for example those that incorporate agroforestry elements, have been proposed as a solution that could maintain and improve multiple ecosystem services. However, habitat diversification in and around arable fields has complex and inconsistent effects on invertebrate crop pests and their natural enemies. This hinders the development of policy recommendations to promote the adoption of such management strategies for the provision of natural pest control services. Here, for the first time we conducted a trait-based approach to investigate the effect of farming system on plant, invertebrate herbivore and invertebrate natural enemy communities. We then evaluated this approach by comparing the results to those generated using a traditional taxonomic approach. At each of three working farms, we sampled within an agroforestry field (a diverse farming system comprising alleys of arable crops separated by tree rows), and within a paired non-diversified area of the farm (arable control field). Each of 96 sample points was sampled between eight and ten times, yielding 393,318 invertebrate specimens from 344 taxonomic groups. Diet specialization or granivory, lack of a pupal stage, and wing traits in invertebrates, along with late flowering, short flowering duration, creeping habit and perenniality in plants, were traits more strongly associated with agroforestry crop alleys than the arable control fields. We hypothesize that this is a result of reduced habitat disturbance and increased habitat complexity in the agroforestry system. Taxonomic richness and diversity were higher in the agroforestry crop alleys compared to the arable control fields, but these effects were stronger at lower trophic levels. However, functional trait diversity of natural enemies was significantly higher in the agroforestry crop alleys than the arable control fields, suggesting an improved level of biocontrol, which was not detected by traditional diversity metrics. Of eight key pest taxa, three were significantly suppressed in the agroforestry system, whilst two were more abundant, compared to the arable control fields. Trait-based approaches can provide a better mechanistic understanding of farming system effects on pests and their natural enemies, therefore we recommend their application and testing in future studies of diversified farming systems.