Theoretical Frameworks for Ecological Dynamics Subject to Stoichiometric Constraints

受化学计量约束的生态动力学理论框架

• 批准号: 0077790
• 负责人: Yang Kuang
• 金额: $ 21.5万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-01 至 2005-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0077790&HistoricalAwards=false
• 关键词: Theoretical; Frameworks; Ecological; Dynamics; Subject

Kuang0077790 All organisms are composed of multiple chemical elementssuch as carbon, nitrogen, and phosphorus. Recent research in thearea known as ecological stoichiometry has highlighted theecological importance of the relative abundance of chemicalconstituents, known to vary considerably among species and acrosstrophic levels. However, most theoeretical studies in ecologyhave until very recently ignored the sources and consequences ofthis chemical heterogeneity. The investigator and his colleaguesundertake theoretical investigations of ecological stoichiometry.They develop a relatively new theoretical framework forecological dynamics that explicitly incorporates stoichiometricconstraints. This base model involves a stoichiometriccounterpart of the familiar Rosenzweig-MacArthur equations inwhich the effective carrying capacity of the resource species andthe transfer efficiency of the consumer species are constrainedby stoichiometric principles. Introduction of stoichiometricconsiderations in these equations (here, akin to "food quality")allows for a rich array of ecologically realistic dynamics,including deterministic extinction of the consumer species whenresources are abundant but of poor quality. They expand thismodel in five different directions, to explore ecologicalrealities (i.e., complications) whose consideration has provedilluminating in other, non-stoichiometric settings. Specifically,they analyze the dynamics of 1) a multi-nutrient model; 2)trophically complex models in which multiple consumer speciesshare a resource; 3) time delays in nutrient recycling that are arealistic component of terrestrial ecosystems; 4) two patchmodels featuring habitat heterogeneity and dispersal of theconsumer; and 5) age structured models in which juvenile andadult consumers differ in their nutrient requirements. Theproject aims to provide an analytically rigorous foundation forburgeoning empirical research into ecological stoichiometry. All living things, including humans, are constructed ofapproximately the same set of basic building blocks, chemicalelements such as carbon (C), nitrogen (N), phosphorus (P), andseveral dozen more in smaller amounts. However, differentorganisms contain different proportions of these key elements intheir biomass and thus must extract these elements from theirenvironment to differing degrees. In many situations, theenvironment does not provide these key nutrient elements in theabundance and proportions that are optimal for organism growthand reproduction. Thus, the chemical environment of life may setlimits on the success of organisms in various situations. In thisproject the investigators use mathematical models to simulate theflow of multiple chemical elements in natural food webs to betterunderstand how the requirements of living things for multiplechemical elements establish key feedbacks between the living andnon-living world. This work is important for two reasons. First,it may provide a better fundamental understanding of how chemicalelements move through food webs. Second, improved fundamentalknowledge of how nutrients move in the environment and how tosimulate those movements with mathematical tools may help predictand manage natural and human-dominated ecosystems, includingthose affected by nutrient inputs from human activities (e.g. Nand P inputs from fertilizer, sewage) or by global change (e.g.effects of increased atmospheric carbon dioxide on C and nutrientflow in the environment).

所有的生物体都是由多种化学元素组成的，如碳、氮和磷。最近在生态化学计量学领域的研究强调了化学成分相对丰度的生态重要性，已知化学成分的相对丰度在物种和跨地转水平之间存在很大差异。然而，直到最近，生态学中的大多数理论研究都忽略了这种化学异质性的来源和后果。这位研究人员和他的同事们从事生态化学计量学的理论研究。他们发展了一个相对新的理论框架，预测动力学明确地纳入了化学计量学的约束。该基本模型与常见的Rosenzweig-MacArthur方程的化学计量相对应，其中资源物种的有效承载能力和消费物种的转移效率受化学计量原理的约束。在这些方程式中引入化学计量学考量(这里类似于“食品质量”)允许丰富的生态现实动态，包括当资源丰富但质量较差时消费物种的确定性灭绝。他们从五个不同的方向扩展了这个模型，以探索生态现实(即复杂性)，这一考虑已被证明在其他非化学计量环境中具有启发性。具体地说，他们分析了1)多营养模型；2)营养复杂模型，其中多个消费物种共享资源；3)营养循环的时间延迟，这是陆地生态系统的实际组成部分；4)两个斑块模型，反映了消费者的栖息地异质性和分散性；以及5)年龄结构模型，其中青少年和成年消费者的营养需求不同。该项目旨在为新兴的生态化学计量学实证研究提供严格的分析基础。所有生物，包括人类，都是由几乎相同的一套基本构件、化学元素，如碳(C)、氮(N)、磷(P)和几十种更少的元素组成的。然而，不同的生物在其生物量中含有不同比例的这些关键元素，因此必须从其环境中提取这些元素的不同程度。在许多情况下，环境提供的这些关键营养元素的丰度和比例对有机体的生长和繁殖都不是最理想的。因此，生命的化学环境可能会限制有机体在各种情况下的成功。在这个项目中，研究人员使用数学模型模拟多种化学元素在天然食物网中的流动，以更好地理解生物对多种化学元素的需求如何在生物和非生物世界之间建立关键反馈。这项工作之所以重要，有两个原因。首先，它可能提供了对化学元素如何在食物网中移动的更好的基本理解。第二，改善营养物质在环境中如何移动的基础知识，以及如何用数学工具模拟这些移动，可能有助于预测和管理自然和人类主导的生态系统，包括受人类活动的营养输入(例如，化肥、污水的氮磷输入)或全球变化(例如，大气二氧化碳增加对环境中的碳和营养流动的影响)影响的生态系统。