RESOURCE MANAGERS WITHIN THE WESTERN U.S. AND ELSEWHERE HAVE BEGUN TO SEE RECRUITMENT FAILURES IN SEMI-ARID FORESTS IN RECENT DECADES. INCREASED FIRE FREQUENCY SIZE AND SEVERITY ALONG WITH DROUGHT AND EXTREME TEMPERATURE EVENTS HAVE DRAMATICALLY INCREASED REFORESTATION NEEDS. THESE NEEDS ARE OUT-PACING THE ABILITY OF MANAGERS TO RESPOND AND THIS TREND IS EXPECTED TO CONTINUE AND/OR ACCELERATE. THE PRIMARY GOAL OF THIS PROJECT IS TO MODEL THE LIKELIHOOD OF RECRUITMENT FAILURE IN SEMI-ARID FORESTS OF THE WESTERN US - AN IMPORTANT PRECURSOR TO THE LOSS OF FOREST ECOSYSTEMS. THE PROPOSED WORK INTEGRATES EARTH OBSERVATION DATA IN-SITU DATA AND A COUPLED ECOHYDROLOGIC/PLANT HYDRAULICS MODEL TO SIMULATE LOSS OF HYDRAULIC FUNCTION AND LETHAL SURFACE TEMPERATURES FOR CONIFER SEEDLINGS. WE FOCUS ON THESE INDICATORS BECAUSE THEY ARE CRITICAL DRIVERS OF SEEDLING MORTALITY IN SEMI-ARID REGIONS GLOBALLY. OUR WORK FLOW WILL ALLOW US TO ESTIMATE THE CAPACITY OF SEMI-ARID FORESTS TO NATURALLY REGENERATE GIVEN PROJECTED FUTURE CLIMATE VARIABILITY. FURTHER OUR PROJECT ADDRESSES SUSTAINABLE DEVELOPMENT GOAL (SDG) 15 TARGETS 15.1 AND 15.2 FOCUSING SPECIFICALLY ON INDICATORS 15.1.1 (FOREST AREA AS A PROPORTION OF TOTAL LAND AREA) AND 15.2.1 (PROGRESS TOWARDS SUSTAINABLE FOREST MANAGEMENT). WE PROPOSE A MODEL-DATA ASSIMILATION FRAMEWORK THAT WILL SUPPORT REFORESTATION PLANNING BY ENABLING THE USFS TO PRIORITIZE AND DEVELOP MORE TARGETED AND EFFICIENT PLANTING EFFORTS. WE BUILD CAPACITY IN AN AREA THAT THE AGENCY IS CURRENTLY LACKING; IDENTIFYING SITES AND CONDITIONS WHICH WILL NO LONGER SUPPORT NATURAL REGENERATION. WE WILL DEVELOP A SUITE OF HIGH RESOLUTION (30 M) GRIDDED PRODUCTS FOR THE WESTERN UNITED STATES THAT QUANTIFY PLANT HYDROLOGIC AND PHYSIOLOGICAL STRESS THE LIKELIHOOD OF SEEDLING MORTALITY AND INTEGRATE THESE PRODUCTS INTO AN EXISTING REFORESTATION DECISION SUPPORT SYSTEM (DSS) DEVELOPED BY THE USFS. THIS WORK WILL LEVERAGE EXISTING RESEARCH OF THE PIS FUNDED BY NASA AND THE NATIONAL SCIENCE FOUNDATION AND WILL ALLOW FOR INVESTMENTS IN BASIC SCIENCE TO BE TRANSLATED TO OPERATIONAL TOOLS FOR DECISION MAKING.