Shrub canopy cover can take between 10 and >50 years to recover to predisturbance levels following fire in sagebrush communities. The high degree of unpredictability of shrub recovery following prescribed fires and wildfires makes it difficult to prioritize restoration efforts and develop long-term plans for restoring or maintaining the integrity of sagebrush communities. Our overall goal was to develop a hypothesis based on descriptive data that describes the temporal pattern of recruitment for 2 important shrubs, Artemisia tridentata Nutt. ssp. vaseyana (Rydb.) Beetle and Purshia tridentata (Pursh) DC., in the interiors of large burns where little seed input from surviving shrubs occurs. We had 2 primary questions: (1) are there distinct temporal patterns of recruitment in the interiors of large burns that determine the recovery rate of the shrub canopy layer for species largely dependent on seedlings for reestablishment and (2) can we generate hypotheses that explain this variation in shrub recovery rates? To address the question of recruitment, we measured shrub density and age for A. tridentata ssp. vaseyana and P. tridentata in the interiors of 4 large (>400-ha) burns. Time since fire varied from 6 to 41 years. All 4 fires burned in August and were relatively complete with few to no unburned patches. Our data indicate that (1) A. tridentata ssp. vaseyana and P. tridentata seed remained viable up to 4 years postfire and that (2) the rate of shrub recovery is largely determined by the success or failure of seedling establishment in the first 2–3 years following disturbance. From these data we generated a hypothesis describing 2 scenarios of postfire shrub recovery.
Western North American Naturalist
Vol. 69 • No. 2
Vol. 69 • No. 2