College of Science and Engineering, James Cook University, Townsville, QLD, Australia.
The Fenner School of Environment and Society, Australian National University, Canberra, ACT, Australia.
Oecologia. 2024 Dec;206(3-4):293-304. doi: 10.1007/s00442-024-05630-y. Epub 2024 Oct 25.
Herbivore-plant interactions are fundamental processes shaping ecosystems, yet their study is challenged by their complex connections within broader ecosystem processes, requiring a nuanced understanding of ecosystem dynamics. This study investigated the relationship between nutrient availability and insect herbivory in the Australian Wet Tropics. Our objectives were threefold. Firstly, to understand what factors influence nutrient availability for plants and herbivores across the landscape; secondly, to investigate how trees of different species respond to nutrient availability; and thirdly, to unravel how the relationships between resources and plant chemistry affect herbivory. We established a network of 25 study sites covering important abiotic gradients, including temperature, precipitation, and geology. Employing a hierarchical modelling approach, we assessed the influence of climate and geology on resource availability for plants, primarily in the form of soil nutrients. Then, we explored the influence of the above factors on the interaction between herbivory and foliage chemistry across three widespread rainforest tree species, comparing how these relationships emerged across genera. Our findings suggest an overarching influence of climate and geology over soil chemistry, foliar nitrogen, and insect herbivory, both directly and indirectly. However, individual constituents of soil fertility showed equivocal influences on spatial patterns of foliage chemistry once site geological origin was accounted for, suggesting a questionable relationship between individual soil nutrients and foliar composition. We have demonstrated that herbivore-plant interactions are complex dynamics regulated by an intricate web of relationships spanning different biogeochemical processes. While our results provide some support to the notion that herbivory is affected by resource availability, different species growing under the same conditions can show differing responses to the same resources, highlighting the importance of identifying specific limiting factors rather than simpler proxies of resource availability.
食草动物-植物相互作用是塑造生态系统的基本过程，但由于它们与更广泛的生态系统过程之间的复杂联系，对其进行研究具有挑战性，这需要对生态系统动态有细致入微的理解。本研究调查了澳大利亚湿热带地区养分供应与昆虫食草之间的关系。我们的目标有三个。首先，了解影响景观中植物和食草动物养分供应的因素；其次，研究不同物种的树木如何对养分供应做出反应；最后，揭示资源与植物化学物质之间的关系如何影响食草作用。我们建立了一个由 25 个研究点组成的网络，涵盖了重要的非生物梯度，包括温度、降水和地质。我们采用分层建模方法评估了气候和地质对植物资源（主要以土壤养分的形式）供应的影响。然后，我们探索了上述因素对三种广泛分布的雨林树种之间食草作用与叶片化学物质相互作用的影响，比较了这些关系在属间的出现方式。我们的研究结果表明，气候和地质对土壤化学、叶片氮和昆虫食草作用具有直接和间接的总体影响。然而，一旦考虑到站点地质起源，土壤肥力的个别组成部分对叶片化学物质空间模式的影响就存在争议，这表明个别土壤养分与叶片组成之间的关系值得怀疑。我们已经证明，食草动物-植物相互作用是复杂的动态过程，由跨越不同生物地球化学过程的复杂关系网络调节。虽然我们的结果提供了一些支持，即食草作用受资源供应的影响，但在相同条件下生长的不同物种对相同资源的反应可能不同，这凸显了确定特定限制因素而不是资源供应的简单替代物的重要性。
