Institute for Environmental Sciences, RPTU University of Kaiserslautern-Landau, Landau, Germany.
Department of Biology, Memorial University of Newfoundland and Labrador, St. John's, Newfoundland and Labrador, Canada.
Ecology. 2023 May;104(5):e4023. doi: 10.1002/ecy.4023. Epub 2023 Mar 27.
Resource quantity and quality can differ between adjacent ecosystems, and these differences can impact subsidies exchanged between ecosystems. The quantity and quality of subsidies are rapidly changing in response to stressors associated with global environmental change, but while we have models to predict the effects of changes in subsidy quantity, we currently lack models to predict the effects of changes in subsidy quality on recipient ecosystem functioning. We developed a novel model to predict the effects of subsidy quality on recipient ecosystem biomass distribution, recycling, production, and efficiency. We parameterized the model for a case study of a riparian ecosystem subsidized by pulsed emergent aquatic insects. In this case study we focused on a common measure of subsidy quality that differs between riparian and aquatic ecosystems: the higher content of long-chain polyunsaturated fatty acids (PUFAs) in aquatic ecosystems. We analyzed how changes in the PUFA concentration of aquatic subsidies affect the dynamics in biomass stocks and functions of the riparian ecosystem. We also conducted a global sensitivity analysis to identify key drivers of subsidy impacts. Our analysis showed that subsidy quality increased the functioning of the recipient ecosystem. Recycling increased more strongly than production per unit subsidy quality increase, meaning there was a threshold where an increase in subsidy quality led to stronger effects of subsidies on recycling relative to the production of the recipient ecosystem. Our predictions were most sensitive to basal nutrient input, highlighting the relevance of recipient ecosystem nutrient levels to understanding the effects of ecosystem connections. We argue that recipient ecosystems that rely on high-quality subsidies, such as aquatic-terrestrial ecotones, are highly sensitive to changes in subsidy-recipient ecosystem connections. Our novel model unifies the subsidy hypothesis and food quality hypothesis and provides testable predictions to understand the effects of ecosystem connections on ecosystem functioning under global changes.
相邻生态系统之间的资源数量和质量可能存在差异，这些差异会影响生态系统之间的物质交换。由于全球环境变化带来的压力，补贴的数量和质量正在迅速变化，但我们有模型可以预测补贴数量变化的影响，而目前缺乏预测补贴质量变化对受纳生态系统功能影响的模型。我们开发了一种新的模型来预测补贴质量对受纳生态系统生物量分布、再循环、生产和效率的影响。我们为一个受脉冲式水生昆虫补给的河岸生态系统的案例研究对模型进行了参数化。在这个案例研究中，我们关注的是河岸和水生生态系统之间存在差异的一种常见的补贴质量衡量标准：水生生态系统中长链多不饱和脂肪酸（PUFA）的含量较高。我们分析了水生补贴物中 PUFAs 浓度的变化如何影响河岸生态系统生物量存量和功能的动态变化。我们还进行了全局敏感性分析，以确定补贴影响的关键驱动因素。我们的分析表明，补贴质量提高了受纳生态系统的功能。与单位补贴质量增加相对应的，再循环的增加比生产的增加更强烈，这意味着在补贴质量增加的情况下，存在一个阈值，使补贴对再循环的影响相对于受纳生态系统的生产更强。我们的预测对基础养分输入最敏感，这突出了受纳生态系统养分水平对于理解生态系统连接对生态系统功能的影响的重要性。我们认为，依赖高质量补贴的受纳生态系统，如水陆交错带，对补贴-受纳生态系统连接的变化高度敏感。我们的新模型统一了补贴假说和食物质量假说，并提供了可测试的预测，以了解在全球变化下生态系统连接对生态系统功能的影响。
