RANGELANDS ARE THE MOST PERVASIVE LAND-USE GLOBALLY AND MOST GRAZING OCCURS IN DRYLANDS. CHRONIC ARIDITY COUPLED WITH HIGH INTERANNUAL CLIMATE VARIABILITY AND LOW SOIL NUTRIENT CONTENT IN DRY RANGELANDS CAN LIMIT NATIVE FORAGE PRODUCTION AND PROMOTE TRANSITIONS TO DEGRADED STATES. EFFORTS TO RESTORE FORAGE AND CURB EROSION OFTEN HAVE LOW SUCCESS RATES. AS A RESULT, UNDERSTANDING HOW TO UTILIZE INTERACTIONS AMONG SOIL BIOLOGICAL COMMUNITIES AND PLANTS TO IMPROVE RESTORATION EFFORTS IS RECEIVING GREATER ATTENTION. BIOCRUSTS ARE SOIL SURFACE COMMUNITIES COMMON TO DRYLANDS. BIOCRUSTS CONSIST OF CYANOBACTERIA, LICHENS, AND MOSSES--ALL OF WHICH ARE PHOTOSYNTHETIC--AND VARIOUS HETEROTROPHIC MICROBES (BACTERIA AND FUNGI) THAT CONSUME CARBON PRODUCTS PRODUCED BY PHOTOSYNTHETIC ORGANISMS. BIOCRUST ASSEMBLAGES CAN AFFECT PLANTS VIA CHEMICAL EXUDATIONS, FOR EXAMPLE, NITROGEN COMPOUNDS PRODUCED TO TOLERATE DESICCATION IN DRY ENVIRONMENTS, BUT THESE PRODUCTS VARY ACROSS BIOCRUST SOIL-MICROBIOMES DOMINATED BY DIFFERENT PHOTOAUTOTROPHS. THIS VARIATION LEADS TO DIFFICULTY IN PREDICTING THE OUTCOMES OF BIOCRUST-SOIL-PLANT INTERACTIONS ACROSS SYSTEMS. UNDERSTANDING HOW BIOCRUST-MICROBIOME VARIATION AFFECTS PLANT PERFORMANCE COULD BE KEY TO SUSTAINABLE AND ECONOMICAL PRACTICES THAT ENHANCE FORAGE PRODUCTION. OUR GOAL IS TO QUANTIFY THE VARIATION WITHIN BIOCRUST-SOIL MICROBIOMES AND UNDERSTAND ITS INFLUENCE ON RANGELAND PLANT PERFORMANCE IN THE PRESENCE OF DROUGHT AND GRAZING. WE HYPOTHESIZE THAT VARIATION IN BIOCRUST PHOTOAUTOTROPHS WILL STRUCTURE THE LARGER SOIL MICROBIOME AND ALTER PLANT-AVAILABLE NUTRIENTS AND COMPOUNDS IN SURFACE SOILS WITH IMPORTANT CONSEQUENCES FOR PLANT PERFORMANCE. WE WILL ASSESS PLANT RESPONSES TO THE COMBINED AND INDIVIDUAL INFLUENCES OF DROUGHT, GRAZING, AND VARIATION IN SOIL MICROBIOMES IN FIELD-BASED SETTINGS AND GREENHOUSE STUDIES THAT QUANTIFY PLANT GERMINATION, GROWTH, SURVIVAL, AND STRESS LEVELS USING A SERIES OF MULTI-OMICS APPROACHES IN BOTH THE PLANT AND SOIL MICROBIOMES. THIS RESEARCH IS POTENTIALLY TRANSFORMATIVE IN ITS ABILITY TO PREDICT PLANT-SOIL INTERACTIONS AND IMPROVE MANAGEMENT OF FORAGE PRODUCTION IN RANGELAND SYSTEMS.