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.
