Tuesday, August 7, 2007

PS 28-48: Natural recovery processes following wildland fire in high quality sagebrush steppe rangeland in southeastern Idaho

Roger D. Blew1, Amy D. Forman1, Jackie R. Hafla1, Mike Pellant2, and Robert D. Jones3. (1) Idaho National Laboratory, (2) Bureau of Land Management, (3) U.S. Department of Energy

We assessed vegetation change within livestock exclosures following a 2000 wildland fire in high quality sagebrush steppe rangeland.  Post-fire plant cover was dominated by native perennial grasses, forbs and resprouting shrubs, but big sagebrush was still absent four years after fire.  Recovery of perennial grasses following fire was not driven by recruitment, but rather from resprouting.  Perennial forbs did not increase in cover following the second year after fire suggesting they had completed recovery by that time.  An early abundance of legumes suggests the immediate post-fire period is important for nitrogen input to sagebrush steppe.  Annuals contributed little toward total cover and did not appear to act as pioneer species as predicted by traditional rangeland successional models.  Introduced annual grass cover was quite low and did not change during the study.  Native annual forbs acted as ephemerals responding to amount and timing of precipitation.  Species richness was higher in 2002 and 2004 than in 2003 due primarily to the absence of native annual forbs in 2003.  Our results indicate that vigorous native perennial forbs, grasses and resprouting shrubs have the ability to recover even under adverse conditions such as the severe drought experienced during this study.  The resulting healthy native plant communities appear to be at less risk to post-fire invasion by non-native species.  They are also less likely to require active restoration unless there is an immediate need to re-establish big sagebrush.  Since the response of a high quality sagebrush steppe to fire does not require grass, forb, or resprouting shrub recruitment, rehabilitation strategies should focus on maintaining vigor of these native perennial species.

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