ABOVEGROUND BIOMASS IS A CRITICAL ELEMENT OF THE GLOBAL CARBON CYCLE BOTH IN TERMS OF THE LARGE MAGNITUDES OF CARBON STORED IN ABOVEGROUND WOODY MATERIAL AND THE ECOLOGICAL CARBON-CLIMATE FEEDBACKS RELATED TO DISTURBANCES FROM PESTS AND FIRE WHICH ARE IMPORTANT FOR CARBON CYCLING IN THE BOREAL SYSTEM. TO DATE HIGH RESOLUTION BIOMASS MAPS HAVE BEEN LARGELY UNAVAILABLE ACROSS THE BOREAL SYSTEM DUE TO A DEARTH OF ACTIVE REMOTE SENSING DATA SENSITIVE TO FOREST STRUCTURE AT THE SPATIAL SCALES OF BOREAL FOREST PROCESSES (~30M 1 HA). THIS RESEARCH WILL PRODUCE AN ABOVE-WIDE BIOMASS MAP FROM ICESAT-2 DATA AND ASSESS THE BIOMASS FLUX ASSOCIATED WITH LAND DISTURBANCE AND REGENERATION BY COMPARING OUR 2020 PRODUCT WITH A 2010 REPRESENTATIVE BIOMASS MAP AND RECOVERY TRAJECTORIES FROM ATTRIBUTED LANDSAT-DERIVED DISTURBANCE PRODUCTS. THE OBJECTIVES OF THIS RESEARCH ARE TO 1) DEVELOP BOREAL ICESAT-2 BIOMASS MODELS USING EXISTING FIELD PLOT DATA AND DISCRETE RETURN AIRBORNE LIDAR DATA; 2) PRODUCE A BOREAL FOREST BIOMASS DENSITY MAP FOR THE ABOVE DOMAIN AT 1 HA SPATIAL RESOLUTION REPRESENTING 2019-2021 USING ICESAT-2 DATA AND TEMPORALLY COINCIDENT LANDSAT PRODUCTS; 3) UTILIZE DATA FROM THE 2017 LVIS CAMPAIGN FOR PRODUCT VALIDATION; AND (4) ASSESS THE 2010-2020 BIOMASS FLUX ASSOCIATED WITH KEY DISTURBANCE AGENTS. METHODS THE PROPOSED RESEARCH FOCUSES ON GENERATING AN ABOVE DOMAIN ICESAT-2 BIOMASS PRODUCT VALIDATING THE PRODUCT WITH 2017 LVIS DERIVED BIOMASS MAPS AND APPLYING THE PRODUCT TO CONDUCT AN ANALYSIS OF BIOMASS FLUX. TO GENERATE THE BIOMASS PRODUCT WE WILL FIRST BUILD EMPIRICAL MODELS FROM A NETWORK OF LINKED FIELD AND DISCRETE RETURN AIRBORNE LIDAR DATASETS (NEON G-LIHT OTHERS). WE WILL USE AN ICESAT-2 SIMULATOR TO GENERATE ICESAT-2 HEIGHT METRICS OVER FIELD PLOTS FOLLOWING THE GENERAL APPROACH ADOPTED BY THE GEDI TEAM. WE WILL APPLY THE ICESAT-2 BIOMASS MODEL TO 100-M ALONG TRACK TRANSECTS OF REAL ICESAT-2 DATA FROM 2019-2021 AND GENERATE A GRIDDED 1HA PRODUCT THROUGH FUSION WITH LANDSAT CANOPY COVER PRODUCTS. WE VALIDATE THIS PRODUCT WITH BIOMASS MAPS THAT WE WILL GENERATE FROM THE 2017 AIRBORNE LVIS CAMPAIGN. FINALLY WE APPLY THIS PRODUCT TO CONDUCT AN ANALYSIS OF BIOMASS FLUX ASSOCIATED WITH FOREST DISTURBANCES FROM WILDFIRE HARVEST AND NON-STAND REPLACING DISTURBANCES. THIS BIOMASS FLUX ANALYSIS RELIES ON COMBINING OUR 2020 REPRESENTATIVE MAP WITH A 2010 BIOMASS MAP ACROSS THE REGION AND A 35 YEAR ATTRIBUTED LANDSAT DISTURBANCE PRODUCT AVAILABLE THROUGH OUR CANADIAN COLLABORATORS. RELEVANCE THE PROPOSED RESEARCH DIRECTLY ADDRESSES THE ABOVE SOLICITED AREA OF (1) ANALYZING REMOTE SENSING DATA COLLECTED DURING THE 2017 AIRBORNE CAMPAIGN (AAC) TO DEVELOP DATA PRODUCTS. ALS DATA COLLECTED IN 2017 AND 2018 WILL BE USED TO BOTH VALIDATE THE ICESAT-2 SIMULATOR DEVELOP/TRAIN ABOVEGROUND BIOMASS ALGORITHMS. FURTHER THE 2017 LVIS CAMPAIGN DATA WILL BE PROCESSED INTO ABOVEGROUND BIOMASS ESTIMATES AND USED TO VALIDATE THE ICESAT-2 BIOMASS PRODUCTS GENERATED IN THIS STUDY. THE PROPOSED RESEARCH WILL HELP ANSWER THE FOLLOWING SPECIFIC ABOVE TIER 2 SCIENCE QUESTIONS: 'WHAT PROCESSES ARE CONTRIBUTING TO CHANGES IN DISTURBANCE REGIMES AND WHAT ARE THE IMPACTS OF THESE CHANGES?' 'HOW ARE FLORA RESPONDING TO CHANGES IN BIOTIC AND ABIOTIC CONDITIONS?' AND 'HOW ARE THE MAGNITUDES OF CARBON POOLS RESPONDING TO ENVIRONMENTAL CHANGE?' MORE BROADLY THIS WORK WILL DEVELOP THE TOOLS AND ALGORITHMS NEEDED TO EXPAND ICESAT-2 BIOMASS MAPPING BEYOND THE ABOVE DOMAIN ENABLING THE GENERATION OF A BOREAL-WIDE BIOMASS PRODUCT THAT COULD BE MERGED WITH GEDI MAPS AND SERVE AS A VALUABLE INPUT TO NISAR MAPPING EFFORTS. THERE ARE NATURAL SYNERGIES BETWEEN SPACEBORNE LIDAR AND SAR AND NISAR AND ICESAT-2 ARE WELL SUITED FOR FUSION IN THE BOREAL SYSTEM. THIS RESEARCH WILL THEREFORE PROVIDE AN IMPORTANT STEP TOWARD GLOBAL 2020 FOREST BIOMASS ACCOUNTING AND THE ONGOING MONITORING OF BIOMASS CHANGE FOR FUTURE MISSIONS SUCH AS NISAR.