Document: ROG-3-64-41

Late summer irrigation effects on recovery of native sagebrush steppe vegetation and establishment of a crested wheatgrass seeding in areas burned by wildfire.

BLEW, R.D.*

Environmental Science and Research Foundation, Idaho Falls, ID 83405 USA ¹

Abstract:
An area burned by wildfire in the summer of 1996 was partially planted soon after with crested wheatgrass, Agropyron cristatum. Portions of the planted and naturally recovering sagebrush steppe received about 2.5 cm of irrigation during late summer 1996. Because the irrigation occurred when there were no actively growing plants and most of the water likely evaporated quickly, an effect due to the brief irrigation event was not expected. In the first growing season, forb cover in the irrigated areas was only one-half that in the areas not irrigated. Irrigation also reduced cover by native perennials in the areas not planted. In the second growing season, total plant cover was 30 percent lower in the irrigated areas than those not irrigated. However, crested wheatgrass cover increased five fold in the areas watered nearly two years earlier. Cover by forbs and exotic annuals, including cheatgrass, Bromus tectorum, remained lower in the areas irrigated almost three years earlier. These results suggest the unusual irrigation event was an additional disturbance that slowed the natural recovery of native perennial species during the first growing season after the fire. However, the irrigation event sped the establishment of crested wheatgrass where it was planted. The brief irrigation event may have reduced wind erosion, resulting in more crested wheatgrass seeds remaining in the soil to germinate the following spring.

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This abstract is being presented at: 10:30 AM in session:
RESTORATION ECOLOGY AND INVASIONS