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Seeding native species to promote ecosystem recovery after fire

Date: July 24, 2019

The use of prescribed fire to reduce expansion of pinyon and juniper to sagebrush ecosystems is a commonly used by managers but can have unwanted consequences


Prescribed fire operations in Underdown Canyon Demonstration Project.
Prescribed fire operations in Underdown Canyon Demonstration Project.
Expansion and dominance of the highly flammable invasive annual grass, cheatgrass (Bromus tectorum), is transforming native sagebrush ecosystems in the western United States. Invasion is often facilitated by fire, including prescribed fires intended to restore shrub-dominated landscapes. Fire-induced cheatgrass invasion does not occur in all landscapes, however, resulting in a pressing need to understand the ecosystem attributes associated with susceptibility to invasion and to identify appropriate management responses.

In this Demonstration Project, we implemented landscape-scale prescribed burns to examine long-term plant community responses to fire and post-fire seeding treatments in sagebrush ecosystems containing a gradient of pinyon and juniper cover. A Joint Fire Sciences Program Demonstration Area was established in 2001 in Underdown Canyon, a west-to-east draining watershed on the Humboldt-Toiyabe National Forest in the Shoshone Mountains of central Nevada. The study used three pairs of adjacent alluvial fans, distributed along an elevational gradient ranging from 2073 m to 2347 m. One fan in each pair was burned by the USDA Forest Service in 2002 and the other remained unburned (control). Post-fire seeding treatments were located within the burned plots, and included unseeded, seeded with a functionally diverse mix of native perennial species, and seeded with a conventional mix of non-native perennial grass species. We asked (1) how long-term ecosystem resistance to fire-induced cheatgrass invasion varies along major abiotic and biotic gradients, and (2) whether post-fire seeding of perennial species promotes perennial plant establishment and increases resistance to invasion. 

Key Findings

Post-fire vegetation sampling in Underdown Canyon Demonstration Project.
Post-fire vegetation sampling in Underdown Canyon Demonstration Project.
  • Resistance to post-fire cheatgrass invasion varies across the landscape. Resistance is driven by environmental conditions and was high on relatively cool and moist sites at high elevation that had rapid post-fire recovery of native perennials. Post-fire recovery is also strongly influenced by biotic factors, and resistance to invasion was low in sites with high pre-fire tree cover (and low pre-fire perennial herbaceous cover), where post-fire perennial establishment was limited by seed availability. [Urza et al. 2017]
  • Seeding perennial species after burning reduced invasibility in sites with low resistance. Seeding a mix of native perennial shrubs, forbs, and grasses was more effective at increasing perennial cover and inhibiting cheatgrass invasion than seeding a mix of non-native perennial grasses. Native-only seed mixes should be used if restoring native vegetation is a management goal, because non-natives tend to outcompete native species when they are seeded together. [Urza et al. 2019]
  • Our results highlight the need for long-term studies to evaluate plant community responses to prescribed fire, as important treatment differences were not captured in a shorter (3–4 year) post-fire monitoring period.

 

Mule deer, two years after prescribed fire treatment.
Mule deer, two years after prescribed fire treatment.

 

 

 

 

 

 

 

 

 

 

 

Featured Publications

Urza, Alexandra K. ; Weisberg, Peter J. ; Chambers, Jeanne C. ; Board, David ; Flake, Samuel W. , 2019
Urza, Alexandra ; Weisberg, Peter J. ; Chambers, Jeanne C. ; Dhaemers, Jessica M. ; Board, David , 2017


Principal Investigators: 
Principal Investigators - External: 
Peter Weisberg - Department of Natural Resources and Enviromental Science-University of Nevada Reno
Forest Service Partners: 
David Board, Ecologist/Data Analyst: Project field lead, data manager
External Partners: 
Peter J. Weisberg (Co-PI), Professor, University of Nevada-Reno Department of Natural Resources and Environmental Science
Research Location: 
Underdown Canyon, Nevada