Collaborative Proposal: MSB-FRA: Improved Understanding of Feedbacks between Ecosystem Phenology and the Weather-Environment Nexus at Local-to-Continental Scales

物候学——季节的节奏——推动着植被从休眠到活动再回到休眠的年度周期。因此，物候学对许多生态过程至关重要。它还直接影响生态系统的生产力以及人类社会所依赖的许多商品和生态系统服务的生产。重要的是，物候节律对天气的年际变化非常敏感，但它们也可以反过来影响天气本身。因此，陆地生态系统与大气之间存在着物候控制的反馈。该项目将使用数码相机网络（PhenoCam network）的图像，以高时空分辨率跟踪北美从苔原到热带地区的植被物候。结合复杂的计算机模拟，该项目将研究物候控制的生态系统-大气反馈，从西南到大平原，再到美国东北部，跨越气候梯度。这个项目试图回答的问题是，这些反馈对生态系统的运作有多大的影响，在什么样的空间和时间尺度上？从管理和维持健康生态系统的角度来看，这个问题很重要。公众参与科学研究将通过与哈佛森林长期生态研究项目的校园计划和夏季研究计划的合作来实现。通过这些努力，该项目将有助于教育和培训传统上代表性不足的群体。该项目还包括研究生和三名博士后研究助理的跨学科培训和研究机会。来自PhenoCam的图像和数据将继续以近乎实时的方式公开，用于研究和教育。本项目旨在了解物候在多时空尺度上调节生态系统-大气耦合和反馈的作用。研究人员将通过整合模拟模型和观测数据来应用宏观系统方法来研究跨尺度相互作用和紧急现象。首先，他们将使用来自大陆物候观测站PhenoCam网络的数据来开发改进的植被物候模型。然后，他们将进行一系列计算机模拟实验，以研究陆地生态系统与受物候控制的大气/气候系统之间的相互作用。具体而言，本项目研究：(1)物候如何调节大陆尺度生态气候梯度上的生态系统-大气耦合强度？(2)生态系统-大气耦合的季节性在这个梯度内和梯度间是如何变化的？(3)在局地-大陆空间尺度和季节-年际时间尺度上，耦合的生态系统-大气动力学如何影响生态系统功能？研究人员将通过将图像分析方法应用于来自PhenoCam的数字相机图像的时间序列来推导物候指标。正式的模型选择标准将用于测试和评估关键植物功能类型物候的不同模型结构。研究人员将使用一个复杂的地球系统模型和规定的和预测的物候情景来解决他们的关键科学问题。这些分析将得到实证数据驱动分析的补充，这些分析融合了PhenoCam数据、卫星遥感、日常气象数据和网格化再分析产品，以及来自AmeriFlux站点的生态系统-大气二氧化碳、水和能源通量的微气象测量。来自NEON站点的相机和通量数据将在可用时进行整合。这个项目的更广泛的影响将针对正式和非正式的科学教育、科学基础设施的发展和下一代跨学科地球系统科学家的培训。

Phenology--the rhythm of the seasons--drives the progression of vegetation through its annual cycles from dormancy to activity and back to dormancy. Phenology is thus critical for many ecological processes. It also directly influences ecosystem productivity and the production of many goods and ecosystem services on which human society is reliant. Importantly, phenological rhythms are highly sensitive to year-to-year variability in weather, but they can also in turn influence weather itself. Thus, there are feedbacks between terrestrial ecosystems and the atmosphere that are phenologically-controlled. This project will use imagery from a network of digital cameras--the PhenoCam Network--to track vegetation phenology at high spatial and temporal resolution across North America, from tundra to the tropics. Together with sophisticated computer simulations, this project will then investigate phenologically-controlled ecosystem-atmosphere feedbacks across a climatic gradient from the Southwest, through the Great Plains, and into the Northeastern US. The question this project seeks to answer is, How much influence do these feedbacks have on how ecosystems work, and at what spatial and temporal scales? This question is important from the point of view of managing and sustaining healthy ecosystems. Public participation in scientific research will be achieved through collaboration with the Harvard Forest Long-Term Ecological Research Project's Schoolyard program and the Summer Research Program. Through these efforts this project will contribute to the education and training of traditionally under-represented groups. This project additionally includes interdisciplinary training and research opportunities for graduate-level students and three postdoctoral research associates. Imagery and data from PhenoCam will continue to be made publicly available, in near-real time, for research and education.This project strives to understand the role of phenology in mediating ecosystem-atmosphere coupling and feedbacks at multiple spatial and temporal scales. The researchers will apply a macrosystems approach by integrating simulation models and observational data to investigate cross-scale interactions and emergent phenomena. First, they will use data from the PhenoCam network, a continental-scale phenological observatory, to develop improved models of vegetation phenology. Then, they will conduct a hierarchy of computer simulation experiments to investigate interactions between terrestrial ecosystems and the atmosphere/climate system that are controlled by phenology. Specifically, this project investigates: (1) How does phenology regulate the strength of ecosystem-atmosphere coupling across a continental-scale ecoclimatic gradient? (2) How does the seasonality of ecosystem-atmosphere coupling vary within and across this gradient? and, (3) How do coupled ecosystem-atmosphere dynamics influence ecosystem function at local to continental spatial scales and seasonal to interannual timescales? The researchers will derive phenological metrics by applying image analysis methods to time series of digital camera images from PhenoCam. Formal model selection criteria will be used to test and evaluate different model structures for the phenology of key plant functional types. The researchers will tackle their key science questions using a sophisticated earth system model with prescribed and prognostic phenology scenarios. These analyses will be complemented by empirical, data-driven analyses fusing PhenoCam data, satellite remote sensing, daily meteorological data and gridded reanalysis products, and micrometeorological measurements of ecosystem-atmosphere fluxes of CO2, water and energy from AmeriFlux sites. Camera and flux data from NEON sites will be incorporated as these become available. Broader impacts from this project will target formal and informal science education, the development of scientific infrastructure, and training of the next generation of interdisciplinary earth system scientists.