Collaborative Proposal: MRA: Understanding how local-scale controls on litter decomposition shape emergent macrosystem biogeochemical patterns

合作提案：MRA：了解局部规模的凋落物分解控制如何塑造新兴宏观系统生物地球化学模式

• 批准号: 1926413
• 负责人: William Wieder
• 金额: $ 39.17万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1926413&HistoricalAwards=false
• 关键词: Collaborative; Proposal; MRA; Understanding; how

Decomposition of leaf litter is fundamental to carbon and nutrient cycling in terrestrial ecosystems. Soil animals and microorganisms feed on leaves when they fall to the ground, derive energy and nutrients from consuming the leaves, and then are themselves consumed as part of the food chain. An important result of this process is that nutrients reenter the soil in forms available to plants for new growth. Alternatively, much of the carbon in leaves is released into the atmosphere as carbon dioxide, with a smaller proportion being stored as soil organic carbon, which helps to maintain soil fertility. As such, by mediating leaf degradation, decomposers play a fundamental role in recycling plant nutrients and maintaining soil health. Decades of research on leaf decomposition suggests that the speed at which this process occurs is dependent upon temperature and moisture, as well as the nutritional quality of the leaves. This project will test whether knowledge of these three factors is, in fact, adequate to predict leaf decomposition rates. Recent work suggests that they are not, because soil organisms vary at these scales in their inherent ability to decompose leaf matter. A collaborative team will examine the possibility that the soil animals and microorganisms, themselves, are an additional and important control on decomposition rates. If that is the case, the research will also determine how it changes predictions of nutrient and carbon cycling across the continental US in response to environmental change. The study will examine these questions over regional to continental scales, and thus in the context of plant species variation (which determines leaf nutritional quality), and changes in climate. Accurate predictions of nutrient and carbon cycling are necessary for effective management of ecosystems to provide food, fiber and fuel, as well as to support biodiversity, as the environment changes. Whether differences among belowground heterotrophic communities directly affect macrosystem biogeochemical behavior is unknown. Ecosystem theory and biogeochemical models are based on the assumption that they do not, with different belowground communities then assumed to function similarly under the same environmental conditions. As such, the impact of environmental disturbance on macrosystem biogeochemical patterns should be predictable without understanding site-specific differences in belowground communities. Emerging evidence challenges the validity of this assumption of scale invariance and suggests instead that the activities of decomposer communities are uniquely shaped by regional environment. This project tests these competing hypotheses of scale invariance versus scale dependence for litter decomposition. These competing hypotheses have not been evaluated because the design of previous broad scale decomposition experiments aggregates local-scale responses, creating the possibility of statistical inference fallacies that obscure robust tests of the hypothesis of scale invariance. The project addresses this information gap through field experiments, extensively replicated within 18 National Ecological Observatory Network (NEON) sites arrayed across the eastern United States, which fall within seven ecoclimatic domains. The field research will be combined with controlled laboratory studies to quantify site-specific relationships between temperature, moisture, litter quality and decomposition rates, and to evaluate whether the relationships arise through selection by the domain-level environment for particular microbial functional traits. The mechanistic insights and data generated through this empirical work will inform the structure, and be used to directly estimate the parameters, of a biogeochemical model. The model will be used to forecast the sensitivity of macrosystem behavior to the possibility that it emerges from scale-dependent relationships generated by trade-offs which dictate the activities of belowground communities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

叶子垃圾的分解是陆地生态系统中碳和营养循环的基础。土壤动物和微生物掉落到地面时会以叶子为食，从食用叶子中得出能量和养分，然后作为食物链的一部分被食用。这个过程的重要结果是，营养使植物可用于新生长的形式的土壤重新进入。另外，叶子中的大部分碳被释放到大气中，作为二氧化碳，较小的比例被存储为土壤有机碳，这有助于维持土壤的生育能力。因此，通过介导叶子降解，分解剂在回收植物营养和维持土壤健康方面起着基本作用。几十年来对叶子分解的研究表明，此过程发生的速度取决于温度和水分以及叶子的营养质量。该项目将测试对这三个因素的了解实际上是否足以预测叶片分解速率。最近的工作表明，它们不是，因为土壤生物在分解叶子物质的固有能力方面在这些尺度上有所不同。一个协作团队将研究土壤动物和微生物本身是对分解率的额外而重要的控制的可能性。如果是这种情况，研究还将确定它如何改变美国大陆的养分和碳循环的预测，以应对环境变化。 该研究将在区域到大陆尺度上研究这些问题，从而在植物物种变化（决定叶片营养品质）和气候变化的背景下进行研究。对于有效地管理生态系统以提供食物，纤维和燃料以及支持生物多样性，需要对养分和碳循环的准确预测，并且随着环境的变化。地下异养社区之间的差异是否直接影响宏观系统生物地球化学行为尚不清楚。生态系统理论和生物地球化学模型基于以下假设：在相同的环境条件下，假定不同的地下社区在地下社区的功能相似。因此，环境干扰对宏观系统生物地球化学模式的影响应该是可以预测的，而不必了解地下社区中特定地点的差异。新兴的证据挑战了这种规模不变性假设的有效性，而是暗示了分解群落的活动是由区域环境构成的。该项目测试了这些量表不变性与垃圾分解的比例依赖性的相互竞争的假设。这些竞争假设尚未得到评估，因为先前的大规模分解实验的设计汇总了局部规模的响应，从而产生了统计推断谬误的可能性，这些谬论掩盖了对规模不变性假设的强大检验。该项目通过现场实验解决了这一信息差距，该实验在美国东部的18个国家生态观测网络（NEON）站点中广泛复制，该地点属于美国东部的七个生态气候领域。现场研究将与对照实验室研究结合使用，以量化温度，水分，垃圾质量和分解速率之间的现场特异性关系，并评估该关系是否是通过针对特定微生物功能性状的域级环境选择而出现的。通过这项经验工作生成的机械洞察力和数据将为结构提供信息，并用于直接估计生物地球化学模型的参数。该模型将用于预测宏观系统行为的敏感性，以至于它是由由权衡取舍产生的规模依赖关系所产生的，这些关系决定了地下社区的活动。该奖项反映了NSF的法定任务，并认为通过基金会的知识和更广泛的影响，可以通过评估来支持NSF的法定任务。

项目成果

Soil organic carbon models need independent time-series validation for reliable prediction

土壤有机碳模型需要独立的时间序列验证才能进行可靠的预测

• DOI: 10.1038/s43247-023-00830-5
• 发表时间: 2023
• 期刊: Communications Earth & Environment
• 影响因子: 7.9
• 作者: Le Noë, Julia;Manzoni, Stefano;Abramoff, Rose;Bölscher, Tobias;Bruni, Elisa;Cardinael, Rémi;Ciais, Philippe;Chenu, Claire;Clivot, Hugues;Derrien, Delphine
• 通讯作者: Derrien, Delphine

Patterns and controls of foliar nutrient stoichiometry and flexibility across United States forests

• DOI: 10.1002/ecy.3909
• 发表时间: 2023-01-05
• 期刊: ECOLOGY
• 影响因子: 4.8
• 作者: Dynarski, Katherine A.;Soper, Fiona M.;Cleveland, Cory C.
• 通讯作者: Cleveland, Cory C.