THE FOREST-GRASSLAND ECOTONE IN THE SOUTHCENTRAL US IS THE TENSION ZONE BETWEEN TWO MAJOR BIOMES AND PROVIDES A NUMBER OF IMPORTANT BENEFITS INCLUDING TIMBER, FORAGE FOR LIVESTOCK, AND WILDLIFE HABITAT FOR GAME AND NON-GAME SPECIES. ACTIVE MANAGEMENT OF THESE SYSTEMS USING PRESCRIBED FIRE, FOREST THINNING/HARVESTING, GRAZING, AND HERBICIDES CAN OPTIMIZE DESIRED BENEFITS FOR LANDOWNERS WITH A VARIETY OF MANAGEMENT OBJECTIVES. HOWEVER, PERIODIC SEVERE DROUGHTS THAT PLAGUE THIS AREA AND INCREASING CLIMATE VARIABILITY WILL PROFOUNDLY AFFECT THE PRODUCTIVITY, RESILIENCE, AND STABILITY OF ECOSYSTEMS ALONG THIS FOREST-GRASSLAND TENSION ZONE. UNDERSTANDING HOW DROUGHT AND CLIMATE VARIABILITY AFFECT THE PRODUCTIVITY AND ECONOMIC VALUE OF VARIOUS ECOSYSTEM TYPES WITHIN THE ECOTONE IS KEY TO SUSTAINABLY MANAGE THIS REGION FOR MULTIPLE OBJECTIVES BOTH NOW AND IN THE FUTURE.OUR ULTIMATE GOAL OF THIS PROJECT IS TO FACILITATE SUSTAINABLE MANAGEMENT OF THE FOREST-GRASSLAND ECOTONE FOR DIFFERENT COMBINATIONS OF OBJECTIVES SUCH AS TIMBER, GRAZING, AND WILDLIFE HABITAT BASED ON RECENT CONDITIONS AND TO ADAPT MANAGEMENT TO MITIGATE THE NEGATIVE EFFECTS OF FUTURE DROUGHT AND POTENTIAL CLIMATE CHANGE. OUR OVERALL OBJECTIVES ARE TO 1) DETERMINE HOW ANNUAL VARIATION IN WEATHER (1986-2017), THAT INCLUDES TEMPERATURE AND PRECIPITATION EXTREMES, AND PRESCRIBED FIRE RETURN INTERVAL AFFECT THE PRODUCTIVITY OF COMPONENTS OF DIFFERENT ECOSYSTEMS RANGING FROM CLOSED-CANOPY FOREST TO SAVANNA/GRASSLAND AND 2) DETERMINE ASSOCIATED ECONOMIC BENEFITS GAINED FROM DIFFERENT MIXES OF MANAGEMENT UNDER RECENT CLIMATIC CONDITIONS AND FUTURE CLIMATE SCENARIOS. WE HYPOTHESIZE 1) DROUGHT AND HIGHER THAN NORMAL TEMPERATURES REDUCE TREE GROWTH MORE THAN HERBACEOUS PLANT GROWTH, 2) DROUGHT AND HIGHER THAN NORMAL TEMPERATURES REDUCE GROWTH OF DENSER FORESTS MORE SO THAN LESS DENSE FORESTS, 3) HIGH INTENSITY PRESCRIBED FIRE HAS A NET NEGATIVE EFFECT ON TREE GROWTH AND POSITIVE EFFECT ON HERBACEOUS PLANT GROWTH, 4) YEARS WITH DROUGHT AND ABOVE AVERAGE TEMPERATURE WILL CAUSE A GREATER DECREASE IN ECONOMIC RETURN FOR TIMBER OBJECTIVES THAN FOR CATTLE GRAZING OR WILDLIFE FORAGE, 5) EXTRAPOLATING THE CLIMATE TO HOTTER AND DRIER CONDITIONS WILL RESULT IN GRAZING AND WILDLIFE OBJECTIVES INCREASING IN ECONOMIC VALUE RELATIVE TO TIMBER OBJECTIVES. WHILE PREVIOUS STUDIES MAINLY DETERMINED THE EFFECTS OF WEATHER AND CLIMATE ON GRASSLANDS OR FORESTS SEPARATELY, THIS PROJECT WILL SYSTEMATICALLY MEASURE EFFECTS ACROSS A CONTINUUM OF ECOSYSTEMS WITH DIFFERENT LEVELS OF HERBACEOUS AND TREE DOMINANCE. THIS IS CRITICAL FOR SUSTAINABLE MANAGEMENT ALONG THE FOREST-GRASSLAND ECOTONE WHERE A MOSAIC OF DIFFERENT ECOSYSTEMS EXIST AND WHERE MANAGEMENT CAN READILY SHIFT ECOSYSTEM TYPE.WE ARE UNIQUELY SUITED TO ADDRESS THESE OBJECTIVES. THE PDS ARE INVOLVED WITH MEASURING AND MAINTAINING, AND HAVE ACCESS TO HISTORICAL DATA FROM A RESEARCH INSTALLATION IN SOUTHEASTERN OKLAHOMA THAT HAS BEEN CONTINUOUSLY TREATED AND MONITORED SINCE 1983. TREATMENTS INCLUDE VARIOUS LEVELS OF TREE HARVESTING AND THINNING AS WELL AS FIRE EXCLUSION AND PRESCRIBED FIRE AT ONE, TWO, THREE, AND FOUR YEARS RETURN INTERVALS. THE RESULT IS A RANGE OF ECOSYSTEM TYPES THAT INCLUDE MATURE PINE-OAK FOREST, EVEN-AGED PINE-OAK FOREST, UNEVEN-AGED PINE-OAK FOREST, OPEN WOODLAND, AND SAVANNA. EACH OF THESE DIFFERENT ECOSYSTEM TYPES PRESENTS DIFFERENT MANAGEMENT OPPORTUNITIES FOR TIMBER, GRAZING, AND WILDLIFE. ANNUAL DATA OF UNDERSTORY VEGETATION GROWTH BY FUNCTIONAL GROUP (GRASS, FORB, WOODY, LEGUME, SEDGE) DATING BACK TO 1986 WERE COLLECTED ARCHIVED AND AVAILABLE FOR THE RESEARCH TEAM TO USE. ANNUAL GROWTH FOR WOODY TREES OVER THE SAME TIME PERIOD WILL BE ANALYZED USING DENDROCHRONOLOGICAL TECHNIQUES. THE CLIMATE DATA ARE AVAILABLE FROM DAYMET (THORNTON ET AL., 2017) AND THE TREATMENT PERIOD INCLUDED SEVERAL MAJOR DROUGHT EVENTS.TO FACILITATE MEETING LANDOWNER OBJECTIVES AND OPTIMIZING ECONOMIC RETURN, THE COMMODITY VALUE FOR TIMBER AND CATTLE GRAZING AS WELL AS THE NONMARKET-BASED VALUE OF DEER FORAGE FOR DIFFERENT ECOSYSTEM TYPES AND THE ASSOCIATED EFFECTS OF DROUGHT, CLIMATE VARIABILITY, AND PRESCRIBED FIRE WILL BE DETERMINED. THE ANNUAL VARIATION IN TIMBER BENEFITS WILL BE DETERMINED BY INCORPORATING THE EMPIRICALLY DETERMINED EFFECTS OF FIRE AND CLIMATE VARIABILITY ON TREE PRODUCTIVITY INTO GROWTH AND YIELD MODELS FOR STANDS OF DIFFERENT COMPOSITIONS AND DENSITIES. GRAZING BENEFITS WILL BE QUANTIFIED BY CALCULATING THE ANNUAL CARRYING CAPACITY FOR CATTLE BASED ON ANNUAL GRASS PRODUCTIVITY. BECAUSE WILDLIFE HABITAT IS A BENEFIT NOT READILY TRADED IN MARKETPLACE, NONMARKET-BASED STATED PREFERENCE METHODS WILL BE USED TO QUANTIFY THE VALUE OF DEER. THEN, THE VALUE OF DEER FORAGE PROVIDED BY THE DIFFERENT ECOSYSTEMS WILL BE CALCULATED BASED ON PERCENT OF ANNUAL UNDERSTORY PRODUCTION THAT IS PREFERRED BY DEER. THE COMPONENT VALUES, I.E., TIMBER, CATTLE GRAZING, DEER FORAGE, WILL BE DETERMINED AS WILL THE CUMULATIVE ECONOMIC VALUE PROVIDED BY THE DIFFERENT ECOSYSTEM TYPES UNDER A RANGE OF DROUGHT, MANAGEMENT, AND CLIMATE SCENARIOS.COLLECTIVELY, THESE RESULTS CAN BE USED TO SYSTEMATICALLY ANALYZE HOW PRESCRIBED FIRE AND CLIMATE AFFECT DIFFERENT ECOSYSTEM TYPES, THE PRODUCTIVITY OF THEIR VARIOUS COMPONENTS, AND THE ASSOCIATED ECONOMIC BENEFITS. BY PROVIDING INFORMATION ON THE FINANCIAL TRADEOFFS THAT DIFFERENT ECOSYSTEM TYPES PRESENT FOR VARIOUS OBJECTIVES AND THE EFFECTS OF CLIMATE AND MANAGEMENT, OUR RESULTS WILL ENABLE LANDOWNERS TO MORE PROFITABLY AND SUSTAINABLY MANAGE THEIR LANDS IN THE FACE OF FUTURE DROUGHTS AND UNCERTAIN CLIMATE ALONG THE FOREST-GRASSLAND ECOTONE. THESE EFFORTS WILL IMPROVE THE LIVES OF PEOPLE WITHIN OKLAHOMA AND THROUGHOUT THE CENTRAL FOREST-GRASSLAND TRANSITION ZONE AND, THEREFORE, CONTRIBUTE TO THE CORE LAND-GRANT MISSION OF OKLAHOMA STATE UNIVERSITY.