Department of Biology, Ball State University, Muncie, IN, 47306, USA.
Department of Integrative Biology, University of Guelph, Guelph, ON, NIG2WI, Canada.
Ecol Lett. 2021 Apr;24(4):781-790. doi: 10.1111/ele.13697. Epub 2021 Feb 7.
Peatlands are the most efficient natural ecosystems for long-term storage of atmospheric carbon. Our understanding of peatland carbon cycling is based entirely on bottom-up controls regulated by low nutrient availability. Recent studies have shown that top-down controls through predator-prey dynamics can influence ecosystem function, yet this has not been evaluated in peatlands to date. Here, we used a combination of nutrient enrichment and trophic-level manipulation to test the hypothesis that interactions between nutrient availability (bottom-up) and predation (top-down) influence peatland carbon fluxes. Elevated nutrients stimulated bacterial biomass and organic matter decomposition. In the absence of top-down regulation, carbon dioxide (CO ) respiration driven by greater decomposition was offset by elevated algal productivity. Herbivores accelerated CO emissions by removing algal biomass, while predators indirectly reduced CO emissions by muting herbivory in a trophic cascade. This study demonstrates that trophic interactions can mitigate CO emissions associated with elevated nutrient levels in northern peatlands.
泥炭地是长期储存大气碳的最有效自然生态系统。我们对泥炭地碳循环的理解完全基于受低养分供应调节的自下而上控制。最近的研究表明，通过捕食者-猎物动态的自上而下控制可以影响生态系统功能，但迄今为止尚未在泥炭地进行评估。在这里，我们使用养分富集和营养级操纵的组合来测试以下假设：养分供应（自下而上）和捕食（自上而下）之间的相互作用会影响泥炭地的碳通量。升高的养分刺激了细菌生物量和有机物质的分解。在没有自上而下的调节的情况下，由更大分解驱动的二氧化碳（CO ）呼吸被藻类生产力的升高所抵消。食草动物通过去除藻类生物量来加速 CO 的排放，而捕食者通过在营养级联中抑制食草作用间接减少 CO 的排放。这项研究表明，营养相互作用可以减轻与北方泥炭地升高的养分水平相关的 CO 排放。
