Climate, fire, and trade-offs between conifers

Abrupt shifts in species composition are possible in many ecosystems given novel disturbance regimes and projected climate warming, but such interactions are challenging to detect in contemporary landscapes. We used paleoecological data to examine how fire and climate have interacted to influence abundance of Douglas-fir and lodgepole pine in the forests of northern Yellowstone National Park over the last 3000 years. Present-day forest associations were established in the late Holocene with the onset of cooler wetter conditions. Conifer dominance fluctuated with climate variability and fire; post-fire increases in Douglas-fir were often associated with dry intervals as inferred from PDSI reconstructions.