Global Change Impacts on Ecological Systems

我的研究测试了生物和非生物机制如何相互作用来调节生态系统的多样性和功能，以及这些机制如何被人类的变化所改变。在最简单的层面上，所有生物系统都是由有限资源（光、氮、猎物）的池大小和流动速率形成的。由于气候变化、富营养化、物种引入和营养衰竭等因素经常同时发生，人类以复杂的方式极大地改变了这些池和流，从而影响了多样性和功能。我们的实验室使用从本地到全球范围的经验方法来调查这些问题，目标是基础理论及其在管理中的应用。在接下来的五年里，我的实验室将专注于三个目标：(i)基于资源的植物对北极变化的响应：变暖、降水和氮沉降如何不同地影响“北极绿化”；（ii）多样性、资源保留和农场影响：多样性调节农业景观资源吸收的能力，减少对水的环境影响；（iii）对资源共变变化的弹性。基于生态位的补偿反应如何缓冲或被干旱和氮污染的综合影响所淹没。这些目标是统一的，其目标是理清生物过程（物种相互作用、多样性）和非生物过程（气候、营养）对调节有限资源的相对影响，并对生态系统功能（如抵抗力、复原力、总产量）产生影响。资源的调控一直是通过生态和进化途径描述生物多样性创造和维持的生态模型的核心原则。资源监管也成为理解全球变化的机制影响的门户。这一点在养分方面表现得尤为明显，氮和磷——初级生产力的两种最重要的限制性资源——现在成为全球的主要污染物。我们的工作测试了在人为环境中生物和非生物对资源的影响之间的相互联系。这包括多样性如何通过生态位互补性影响资源，最大化吸收和生产，同时减少入侵物种的可用性（例如，生物抗性）。它还包括非生物因素如何影响资源，特别是当供应超过植物群落的需求（例如，富营养化）或无法满足需求（例如，严重干旱）时。影响环境的多样性（通过对资源的需求）和影响多样性的环境（通过对资源的供应）之间的相互关系，抓住了许多对群落聚集、物种共存和生态位进化模型至关重要的基本机制。它还应该预测基于人类的环境变化如何影响这些过程，这是我研究计划的核心主题。

My research tests how biotic and abiotic mechanisms interact to regulate the diversity and functioning of ecological systems, and how those mechanisms are transformed by human-based change. At the simplest level, all biological systems are shaped by the pool sizes and flows rates of limiting resources (light, nitrogen, prey). Humans affect diversity and function by dramatically altering these pools and flows, in complicated ways because factors such as climate change, eutrophication, species introductions, and trophic collapse often occur simultaneously. Our lab uses empirical approaches, at scales from local to global, to investigate these issues, targeting both fundamental theory and its application to management. For the next five years, my lab will focus on three objectives: (i) Resource-based plant responses to Arctic change: how warming, precipitation, and N deposition variously affect "Arctic greening" (ii) Diversity, resource retention, and farm impacts: the capacity of diversity to regulate resource uptake on agricultural landscapes, reducing environmental impacts on water, (iii) Resiliency to co-varying changes in resources. How niche-based compensatory responses buffer, or are overwhelmed by, the combined effects of drought and N pollution. These objectives are unified in their goal of untangling the relative influences of biotic processes (species interactions, diversity) and abiotic processes (climate, nutrients) on regulating limiting resources, with implications for ecosystem function (e.g., resistance, resilience, total production). The regulation of resources has always been a central tenet of ecological models describing the creation and maintenance of biological diversity, via ecological and evolutionary pathways. Resource regulation has also become a gateway to understand the mechanistic impacts of global change. This is felt especially acutely with nutrients, with N and P - two of the most important limiting resources for primary productivity - now acting as major pollutants globally. Our work tests reciprocal connections between biotic and abiotic influences on resources in anthropogenic environments. This includes how diversity affects resources via niche complementarity, maximizing uptake and thus production, while reducing availability for invading species (e.g., biotic resistance). It also includes how abiotic factors affect resources, especially when supply exceeds the demand of the plant community (e.g., eutrophication) or fails to meet it (e.g., intense drought).The reciprocal relationship between diversity affecting the environment (via the demand for resources) and the environment affecting diversity (via the supply of resources) captures many of the fundamental mechanisms central to models of community assembly, species coexistence, and niche evolution. It should also predict how human-based environmental change affects these processes, a theme that is central to my research program.