MEETING EXISTING BIOFUEL MANDATES AND ACHIEVING FUTURE CARBON-NEGATIVE BIOENERGY GOALS WITHOUT NEGATIVELY IMPACTING FOOD PRODUCTION OR THREATENING REMAINING NATIVE LANDSCAPES WILL LIKELY REQUIRE GROWING DEDICATED BIOMASS FEEDSTOCK CROPS ON SO-CALLED 'MARGINAL' LANDS THAT ARE TOO UNPRODUCTIVE, ENVIRONMENTALLY SENSITIVE, OR DEGRADED FOR USE IN CONVENTIONAL AGRICULTURE. HOWEVER, ECONOMISTS AND ECOLOGISTS DEFINE 'MARGINAL' IN DIFFERENT WAYS, LEADING TO UNCERTAINTY AROUND THE TOTAL AMOUNT OF MARGINAL LAND AVAILABLE, THE COSTS OF CONVERTING IT TO FEEDSTOCK PRODUCTION, AND THE ENVIRONMENTAL IMPACTS AND BENEFITS OF DOING SO. OUR PROJECT WILL SYNTHESIZE ECOLOGICAL AND ECONOMIC PERSPECTIVES TO PRODUCE A UNIFIED ATLAS OF MARGINAL LANDS IN THE US, AS WELL AS INSIGHTS AROUND THE COSTS, POTENTIAL ENVIRONMENTAL BENEFITS, AND OVERALL PRACTICAL LIKELIHOOD OF USING THOSE LANDS FOR BIOMASS FEEDSTOCK PRODUCTION.WE WILL PERFORM SPATIAL ANALYSIS OF A VARIETY OF EXISTING DATA SOURCES TO CLARIFY THE BIOPHYSICAL, ECOLOGICAL, AND SOCIAL FACTORS UNDERLYING MARGINAL LANDS IN DIFFERENT REGIONS OF THE US. WE WILL EVALUATE AND IMPROVE THE ABILITY OF AN ECOSYSTEM MODEL TO PREDICT YIELDS AND ENVIRONMENTAL IMPACTS OF BIOENERGY CROP PRODUCTION ACROSS AREAS OF DIFFERENT LAND QUALITY AND DIFFERENT INITIAL LEVELS OF SOIL HEALTH. SIMULATION RESULTS WILL BE INTEGRATED INTO AN ECONOMIC TECHNOLOGY DIFFUSION MODEL TO PREDICT THE LIKELIHOOD OF AND BARRIERS TO THE WIDESPREAD ADOPTION OF BIOMASS CROPS AND BIOENERGY TECHNOLOGIES, WITH EMPHASIS ON THE POTENTIAL FOR LAND REMEDIATION THROUGH SOIL CARBON IMPROVEMENTS. RESULTS WILL THEN BE SYNTHESIZED INTO A NATIONAL-SCALE ATLAS HIGHLIGHTING THE MARGINAL LANDS MOST APPROPRIATE FOR BIOMASS FEEDSTOCK PRODUCTION CONSIDERING COSTS, ENVIRONMENTAL IMPACTS, AND LAND REMEDIATION POTENTIAL. WE EXPECT THE RESULTING SYNTHESIS WILL BE USEFUL FOR BIOENERGY INDUSTRY PLANNING AND BIOENERGY POLICY DEVELOPMENT, IN ADDITION TO CONTRIBUTING TO BETTER UNDERSTANDING OF THIS CRITICAL SUSTAINABILITY PROBLEM WITHIN THE RESEARCH COMMUNITY.