INCREASING CLIMATE VARIABILITY THREATENS RANGELAND PRODUCTION, A CRITICAL COMPONENT OF RURAL ECONOMIES IN THE CENTRAL AND WESTERN U.S. HOWEVER, IDENTIFYING ACTIONS THAT LAND MANAGERS AND RANCHERS CAN TAKE TO MITIGATE THIS THREAT ARE HAMPERED BY A LIMITED UNDERSTANDING OF THE MECHANISMS THAT DETERMINE HOW RANGELAND PLANT PRODUCTIVITY RESPONDS TO CHANGES IN PRECIPITATION ACROSS DIVERSE DESERT, STEPPE, AND GRASSLAND COMMUNITIES. TRADITIONAL APPROACHES TO INVESTIGATING THE DRIVERS OF RANGELAND PRODUCTIVITY HAVE FOCUSED AT THE WHOLE-COMMUNITY AND ECOSYSTEM-LEVEL, IGNORING THE ROLE OF INDIVIDUAL SPECIES WITHIN ECOSYSTEMS. THE GOAL OF THIS PROJECT IS TO IMPROVE OUR MECHANISTIC UNDERSTANDING OF PRECIPITATION-PRODUCTIVITY PATTERNS AND OUR ABILITY TO FORECAST PLANT PRODUCTIVITY DYNAMICS BY INCORPORATING INFORMATION ON POPULATION DYNAMICS OF INDIVIDUAL SPECIES WITHIN PLANT COMMUNITIES. TO ACCOMPLISH THIS, I WILL: 1) DEVELOP JOINT-SPECIES MODELS THAT CAPTURE THE CONTRIBUTION OF INDIVIDUAL SPECIES AND INTERACTIONS AMONG SPECIES TO ECOSYSTEM LEVEL PRODUCTIVITY; 2) TEST MECHANISTIC HYPOTHESES EXPLAINING CHANGES IN RANGELAND PLANT PRODUCTIVITY ACROSS SPACE AND THROUGH TIME BASED ON THE RESPONSES OF INDIVIDUAL SPECIES TO ABIOTIC AND BIOTIC CONDITIONS; 3) TEST THE ABILITY OF POPULATION-LEVEL DATA TO IMPROVE OUR ABILITY TO FORECAST RANGELAND PLANT PRODUCTIVITY DYNAMICS. MY RESEARCH WILL DIRECTLY LINK ACTIONS MANAGERS CAN TAKE AT THE POPULATION-LEVEL (E.G. SPECIES RESTORATION, INVASIVE SPECIES CONTROL) TO ECOSYSTEM PRODUCTIVITY OUTCOMES. IDENTIFYING THE MECHANISMS DRIVING RANGELAND PRODUCTION AND IMPROVING ECOLOGICAL FORECASTING CAPABILITIES WILL BE CRITICAL FOR THE "SUSTAINABLE USE AND MANAGEMENT OF...RANGELAND[S]" AS IDENTIFIED IN THE BIOENERGY, NATURAL RESOURCES, AND ENVIRONMENT FARM BILL PRIORITY AREA.