Bridging Spatial Scales Using Phenological Measurements to Improve Understanding of Autumn Atmosphere-Biosphere Interactions

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The timing of leaf senescence (coloring and subsequent fall; i.e., phenology) during autumn has potentially large impacts on energy and carbon exchange between mid-latitude land surfaces and the lower atmosphere. However, spatial variations in autumn phenological timing at the plant community level have not been widely measured or analyzed, and underlying environmental drivers are not well understood. Thus, detailed autumn phenological data offer considerable opportunities for assessing landscape-level spatial variations crucial for accurate scaling-up measurements to larger areas or downscaling information from atmospheric general circulation models. In this project, spatial variability of autumn phenological data will be measured and analyzed at the community level, compared to microclimatic, carbon flux, and remote sensing measurements, with an overall goal of contributing to increased accuracy of energy/carbon flux estimates at continental to global scales.This project will address issues that are significant for advancement across the fields of climatology, plant physiology, ecology, and remote sensing. The nature of autumn phenological variability in space and time has not been previously recorded over a large area and combined with supporting measurements. Results from recent studies strongly suggest that understanding stand-level (~50 x 50 m) spatial patterns of autumn plant phenological development (and the environmental processes that drive them) will provide key knowledge needed to improve landscape level estimates of carbon accumulation across the entire growing season when combined with existing data for spring phenology. The spatially concentrated phenological measures produced by this project will provide future near-surface and satellite-derived remote sensing studies with a record of autumn plant development and growth involving species differences, spatial variability, and precise event timing that has not been recorded in the past. Overall, the results of this project will contribute to better understanding of the impacts of climate change on the biosphere, which will increase knowledge of potential future changes, and may allow for better planning relative to societal impacts of anticipated forest vegetation change.