WE PROPOSE TO STUDY THE GROWTH DISTURBANCE AND CARBON DYNAMICS OF NORTHERN-HEMISPHERE FORESTS TO IMPROVE UNDERSTANDING OF ARCTIC/BOREAL TERRESTRIAL ECOSYSTEMS THAT MAY BE APPROACHING A POTENTIAL TIPPING POINT WITH REGARD TO THE RELEASE OF STORED CARBON . WE WILL ESTIMATE RATES OF FOREST-CANOPY DISTURBANCE GROWTH AND CARBON (C; ACRONYMS LIST ON PAGE 22) FLUX BY PAIRING HIGH-ACCURACY SUB-METER RESOLUTION ESTIMATES OF CANOPY COVER AND STRUCTURE WITH GLOBAL LANDSAT-BASED ESTIMATES OF TREE CANOPY COVER AND A>40-YEAR TIME-SERIES OF RECORDS OF STAND DISTURBANCE AGE AND ENVIRONMENTAL CONDITIONS. WE WILL ESTIMATE BOREAL FOREST GROWTH POTENTIAL (AS SITE INDEX SI) AT HIGH (SUB-HECTARE) RESOLUTION PAN-BOREAL AND THEN COUPLE THE RESULTING PREDICTIVE SURFACES INTO DYNAMIC GLOBAL VEGETATION MODELS (DGVMS) TO CONSTRAIN ESTIMATES OF NET C FLUX TO THE ATMOSPHERE. THIS STUDY WILL LEVERAGE NEW METHODS FOR COMBINING THE NASA/USGS LANDSAT ARCHIVE WITH WORLDVIEW SUB-METER STEREO IMAGERY AND WILL: 1) QUANTIFY ECOLOGICAL RELATIONSHIPS BETWEEN STAND STRUCTURE WARMING AND C-FLUX IN BOREAL FORESTS; 2) PRODUCE A GLOBALLY CONSISTENT METHOD TO ESTIMATE SI FROM REMOTELY SENSED OBSERVATIONS; AND 3) PROVIDE HIGH-RESOLUTION PAN-BOREAL MAPS OF FOREST DISTURBANCE HISTORY AND STAND AGE FOR OPEN PUBLIC ACCESS. THE UNDERLYING MOTIVATION FOR THIS PROJECT RELATES TO CLIMATE CHANGE EFFECTS ON ALTERING VEGETATION PRODUCTIVITY DYNAMICS AND C SEQUESTRATION AT CONTINENTAL SCALES ACROSS THE HIGHER NORTHERN LATITUDES. THESE SHIFTS ARE REFLECTED IN CHANGING VEGETATION CANOPY STRUCTURE (COVER AND HEIGHT) WHICH VARIES FROM CONTINUOUS FORESTS OF TALL TREES TO DISCRETE ISOLATED FOREST PATCHES AND EVENLY DISTRIBUTED EXPANSES OF GROWTH-STUNTED TREES. ALTHOUGH VARIATION OCCURS AT SPATIAL SCALES NOT RESOLVED BY MOST EARTH-OBSERVING SATELLITES DUE TO LOCAL ENVIRONMENTAL FACTORS INCLUDING TERRAIN WINTER SNOW AND PERMAFROST ACTIVE LAYER DEPTH WIND AND SOIL CHARACTERISTICS. RECENT STUDIES HAVE FOUND THAT ARCTIC GREENING IS ASSOCIATED WITH DENSIFICATION OF SHRUBS INCREASING BIOMASS AND ESTABLISHMENT OF NEW SHRUBS WITHIN THAWING PATTERNED GROUND FEATURES. HOWEVER THEY HAVE NOT BEEN SUFFICIENTLY COMPREHENSIVE TO ESTABLISH A MAP OF GROWTH POTENTIAL FOR NORTHERN FORESTS.