Detection of vegetation canopy stress dynamics using integrated near-ground, and airborne remote sensing data over coastal and boreal forests

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Monitoring of plant photosynthesis is a critical component to understanding the terrestrial carbon cycle, and requires a detailed understanding of the vegetated land surface. Remote sensing is the ideal technology to observe vegetation characteristics in a spatially continuous mode, however variations in vegetation growth over space and time, requires additional information on soil water and nutrient status and climate. This research program will develop functional relationships between vegetation reflectance (indicative of vegetation functioning), plant light use efficiency (Rue) and coincident measurements of carbon and water fluxes. Our approach focuses on the determination and monitoring of Rue using the remote sensing derived photochemical reflectance index (PRI, (based on canopy reflectance at 531 and 570 nm) and other spectral indices. Modeling Rue at the canopy scale is not straightforward, as PRI is a function of both directional reflectance and plant physiological status. To address these complexities, we have designed and built an innovative, tower-mounted sensor (AMSPEC) which scans the top of the canopy to record changes, every 15 seconds, in leaf functioning.