Collaborative Proposal: MRA: Scaling from Traits to Forest Ecosystem Fluxes and Responses to Climate Change, from Stand to Continent

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Knowledge of changes in forest carbon and water, the “breathing of the ecosystem”, is critical to assess how forests function and the stresses they face, and to predict and manage the Earth environment. However, there are large gaps in our understanding of fluctuations in forest characteristics, and in how they vary in time and space. These gaps hinder our ability to predict how different forests respond to environmental change. This project utilizes an unprecedented opportunity provided by the NSF National Ecological Observatory Network(NEON) to determine how forest response to climate instability depends on the properties (traits) of the plant species in the forest. This project will address critical gaps by clarifying how plant traits that influence forest growth and water use vary with the environment at given sites and across the continental U.S. Researchers will also use state-of-the-art models to provide a new ability to predict forest function from the level of small clusters of trees all the way to the continental scale. They will then use this information to develop a new theory to enhance the ability of ecologists to predict forest ecosystem responses to environmental change. This project will be integrated with broader impacts in student training, and local workshops to communicate the science and its accessibility to the local research and education communities within our institutions and in the proximity of NEON sites, and beyond, to the global research and education communities.This project will provide a mechanistic understanding of the role of traits in determining fluxes for 10 forested NEON sites across the continent and a new paradigm to upscale fluxes from stand to the continental US. Our overarching hypothesis is that species’ traits strongly mediate the temporal and spatial scales of variation in ecosystem responses to climate in relation to carbon and water cycles. We will answer three key questions: (1) How do functional traits vary with environment and climate across forests of the continental USA? For species of NEON sites we will measure traits with crucial influence on water transport, gas exchange and resource economics, test the relationships of traits to climatic factors, and apply these relationships to map traits across forests of the continental USA. (2) How do climate and traits influence forest water use and productivity? We will assimilate the trait data into mechanistic terrestrial ecosystem models to quantify the sensitivity of predicted canopy fluxes to trait diversity within and across sites at multiple time scales. (3) How will shifts in climate, disturbance and species composition influence canopy fluxes? Using parameterized models, we will test the influence of climate and disturbances on ecosystem fluxes, and how these vary depending on trait diversity within and across forest sites.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.