**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE U.S. NATIONAL FORESTS PROVIDE TRILLIONS OF DOLLARS OF ECOSYSTEM SERVICES INCLUDING SOIL RETENTION, NUTRIENT CYCLING, GROUNDWATER RECHARGE, CARBON SEQUESTRATION, AND GREENHOUSE GAS AND CLIMATE REGULATION. WHILE WILDFIRES ARE CRITICAL TO THE ECOLOGY OF MANY OF THESE SYSTEMS, FIRES OF UNPRECEDENTED SIZE, SEVERITY, AND FREQUENCY ARE THREATENING THE SERVICES THEY PROVIDE AND COSTING THE USDA BILLIONS OF DOLLARS IN FIRE SUPPRESSION. THIS IS OF PARTICULAR CONCERN FOR RANGELANDS LIKE CHAPARRAL, OR FIRE-ADAPTED SHRUBLANDS, WHICH STORE ROUGHLY 0.13 PG OF CARBON EVERY YEAR IN THE WESTERN U.S. ALONE, BUT WHOSE CARBON-STORAGE AND GREENHOUSE REGULATION CAPACITY IS LARGELY GOVERNED BY SOIL MICROBIOMES THAT ARE FUNDAMENTALLY ALTERED BY WILDFIRES. WHETHER THE PYROPHILOUS, OR FIRE-LOVING, MICROBES ESTABLISHED POST-FIRE FUNDAMENTALLY ALTER THE FUNCTION OF CHAPARRAL REMAINS LARGELY UNEXPLORED, WITH ONLY 13% OF RESEARCH ON POST-FIRE SOIL MICROBIOMES OCCURRING IN SHRUBLANDS. HERE, WE PROPOSE TO USE ATRAIT-BASED CONCEPTUAL FRAMEWORK, WIDELY USED BY PLANT ECOLOGISTS, TO CHARACTERIZE AND BIN PYROPHILOUS MICROBES INTO FUNCTIONAL GROUPS THAT HELP PREDICT POST-FIRE MICROBIOME FUNCTIONS AND THE IMPACTS OF WILDFIRES ON SOIL CARBON SEQUESTRATION AND GREENHOUSE GAS EMISSIONS. WORKING AT A STRENGTHENING INSTITUTION, WE WILL USE COMPLEMENTARY FIELD AND LABORATORY-BASED APPROACHES TO ADDRESS A KEY USDA PROGRAM AREA PRIORITY OF CHARACTERIZING SOIL MICROBIOMES AND METABOLITES THAT DRIVE CRITICAL ENVIRONMENTAL PROCESSES. WE WILL USE HIGH-RESOLUTION TEMPORAL SAMPLING FROM TWO RECENT CHAPARRAL WILDFIRES, COUPLED WITH METAGENOMIC, ISOTOPIC, AND BIOGEOCHEMICAL TOOLS, AND A LARGE AND UNIQUE CULTURE COLLECTION OF FIRE-ADAPTED MICROBES (200 ISOLATES AND COUNTING) TO PRODUCE A MECHANISTIC UNDERSTANDING OF POST-FIRE MICROBIOME FUNCTION.