Evidence that once healthy plant populations are slow or unable to recover after wildfire and seeding is widespread throughout restoration ecology, particularly in water-limited regions like the Great Basin. While considerable attention has been given to the role of abiotic conditions (e.g. moisture availability) and plant community composition (e.g. cheatgrass competition), less is known about how endogenous changes to population structure following fire influence recovery dynamics. Because recovering populations are dominated by small plants which may have lower survival and reproductive rates, their population dynamics may be altered from pre-disturbance conditions. Using data on 531 post-fire big sagebrush populations where seeding occurred, we parameterized structured-population models to explore how changes in sagebrush population size-structure influence recovery dynamics.
Results/Conclusions
We find that shifts in population size-structure from large to small plants, and resulting transient dynamics, significantly impedes recovery after disturbance. We estimated that 500 of the 531 populations have the potential to grow and recover once a mature population size structure is established. But, 88% of these 500 populations declined, rather than grew, immediately after disturbance and seeding because of the negative demographic effects of a population composed of small plants with low survival and reproduction. Our results suggest that alternative restoration approaches, such as planting some larger plants when seeding, may accelerate recovery.