Plant-mediated and nonadditive effects of two global change drivers on an insect herbivore community
Plant-mediated and nonadditive effects of two global change drivers on an insect herbivore community
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DOI：
10.1890/11-1839.1
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发表时间：
2012-08-01
期刊：
影响因子：
4.8
通讯作者：
Tylianakis, Jason M.
中科院分区：
文献类型：
--
作者：
de Sassi, Claudio;Lewis, Owen T.;Tylianakis, Jason M.
温度升高会改变单个物种的物候和分布。然而，物种间的差异可能会模糊群落对气候的物候反应，或者通过始终支持某些分类群而导致生物同质化。此外，昆虫群落对气候的反应将受到植物介导的影响，这可能会或可能不会掩盖温度上升对昆虫的直接影响。最后，最近关于全球变化驱动因素之间相互作用重要性的证据表明，群落对气候的物候响应可能会被其他驱动因素改变。利用自然温度梯度（由海拔和地形产生），结合实验施氮，研究了温度升高和全球范围内人为氮沉降对半自然草地食草动物群落（鳞翅目昆虫）结构和物候的影响。我们发现，这两种驱动因素，无论是单独的还是联合的，都严重改变了物种的相对丰度和组成如何随时间变化。重要的是，温暖的温度与生物同质化有关，因此，在最温暖的地块上的食草动物组合比在中间或凉爽的地块上的食草动物组合具有更多相似的物种组成。草食动物组成和丰度的变化主要由植物群落的变化介导，在高处理水平下增加的非本地草覆盖是草食动物丰度的最强决定因素。除组成变化外，草食动物总生物量在高氮条件下增加了一倍以上，随着温度的升高增加了四倍以上，这对草食动物作为消费者和猎物资源具有重要的功能意义。非本地植物优势在调节草食动物对变化的响应中发挥着至关重要的作用，结合这两种驱动因素频繁的非加性（积极和消极）影响，以及物种的差异响应，突出表明理解复杂的生态系统响应将受益于在群落规模或更大规模上的多因素、多营养实验。
Warmer temperatures can alter the phenology and distribution of individual species. However, differences across species may blur community-level phenological responses to climate or cause biotic homogenization by consistently favoring certain taxa. Additionally, the response of insect communities to climate will be subject to plant-mediated effects, which may or may not overshadow the direct effect of rising temperatures on insects. Finally, recent evidence for the importance of interaction effects between global change drivers suggests that phenological responses of communities to climate may be altered by other drivers. We used a natural temperature gradient (generated by elevation and topology), combined with experimental nitrogen fertilization, to investigate the effects of elevated temperature and globally increasing anthropogenic nitrogen deposition on the structure and phenology of a seminatural grassland herbivore assemblage (lepidopteran insects).We found that both drivers, alone and in combination, severely altered how the relative abundance and composition of species changed through time. Importantly, warmer temperatures were associated with biotic homogenization, such that herbivore assemblages in the warmest plots had more similar species composition than those in intermediate or cool plots. Changes in herbivore composition and abundance were largely mediated by changes in the plant community, with increased nonnative grass cover under high treatment levels being the strongest determinant of herbivore abundance. In addition to compositional changes, total herbivore biomass more than doubled under elevated nitrogen and increased more than fourfold with temperature, bearing important functional implications for herbivores as consumers and as a prey resource. The crucial role of nonnative plant dominance in mediating responses of herbivores to change, combined with the frequent nonadditive (positive and negative) effects of the two drivers, and the differential responses of species, highlight that understanding complex ecosystem responses will benefit from multifactor, multitrophic experiments at community scales or larger.