WE PROPOSE TO INVESTIGATE THE ROLE OF VEGETATION DYNAMICS ACROSS THE ABOVE STUDY DOMAIN BUILDING UPON OUR EXTENSIVE PRIOR WORK DOCUMENTING CHANGES IN ARCTIC AND BOREAL VEGETATION PRODUCTIVITY OVER THE PAST THREE DECADES USING SATELLITE DATA AND RELATED FIELD MEASUREMENTS. WE WILL EXPAND UPON PAST ACTIVITIES WITH RECENT AND HIGHER RESOLUTION SATELLITE DATA PRODUCTS AS WELL AS LIDAR HYPERSPECTRAL AND SAR DATA FROM THE ABOVE AIRBORNE CAMPAIGNS. THESE ANALYSES WILL BE COUPLED WITH EXTENSIVE FIELD MEASUREMENTS AND SPECIES-SPECIFIC MODELING TO CAPTURE AREAS OF DOCUMENTED BOREAL TREE PRODUCTIVITY AND MORTALITY AND TUNDRA VEGETATION CHANGES ACROSS CLIMATE AND ENVIRONMENTAL GRADIENTS. OUR INVESTIGATIONS WILL BE IN THE CONTEXT OF EXPLORING MULTIPLE LINES OF EVIDENCE FOR THE PROGRESSION OF AN ARCTIC BOREAL BIOME SHIFT WHERE TREE PRODUCTIVITY DECREASES AND MORTALITY INCREASES IN THE SOUTHERN BOREAL WHILE SUITABILITY FOR RANGE EXPANSION AND DENSIFICATION OF WOODY VEGETATION (E.G. SHRUBS) INCREASES IN THE NORTHERN BOREAL AND ARCTIC TUNDRA.