We present landscape simulation results contrasting effects of changing climates on forest vegetation and fire regimes in Yellowstone National Park, USA, by mid-21st century. We simulated potential changes to fire dynamics and forest characteristics under three future climate projections representing a range of potential future conditions using the FireBGCv2 model. Under the future climate scenarios with moderate warming (>2°C) and moderate increases in precipitation (3-5%), model simulations resulted in 1.2-4.2 times more burned area, decreases in forest cover (10-44%), and reductions in basal area (14-60%). In these same scenarios, lodgepole pine (Pinus contorta) decreased in basal area (18-41%), while Douglas-fir (Pseudotsuga menziesii) basal area increased (21-58%). Conversely, mild warming (<2°C) coupled with greater increases in precipitation (12-13%) suggested an increase in forest cover and basal area by mid-century, with spruce and subalpine fir increasing in abundance. Overall, we found changes in forest tree species compositions were caused by the climate-mediated changes in fire regime (56-315% increase in annual area burned). Simulated changes in forest composition and fire regime under warming climates portray a landscape that shifts from lodgepole pine to Douglas-fir caused by the interaction between the magnitude and seasonality of future climate changes, by climate-induced changes in the frequency and intensity of wildfires, and by tree species response.