Postfire seeding and plant community recovery in the Great Basin

Authors: KULPA, SARAH - Department Of Fish And Wildlife; LEGER, ELIZABETH - University Of Nevada; Espeland, Erin; GOERGEN, ERIN - University Of Nevada

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2011
Publication Date: 3/1/2012
Citation: Kulpa, S., Leger, E., Espeland, E.K., Goergen, E. 2012. Postfire seeding and plant community recovery in the Great Basin. Rangeland Ecology and Management. 65(2): 171–181.

Interpretive Summary: The success of post-fire reseeding is known to be variable, with little information regarding what promotes success of rangeland seeding on the within-site scale. Here we measure the establishment of seeded species and regrowth of remnant native species at five sites in eastern Nevada over the course of three years. We find that native species are most likely to establish naturally post-burn on north-facing aspects and that seeds are most likely to successfully establish in flat areas. Thus, the expense of seeding north facing slopes after fire may be unnecessary. Densities of plants in three functional groups (seeded grasses, non-seeded grasses, cheatgrass) measured in the first year predicted their densities in the third year. In addition, we find that high-efficiency frequency measures correlate with more time-intensive density measurements. These results indicate that post-fire monitoring can be performed quickly with frequency measurements and need not take place every year. With these savings in resources, longer-term datasets should be more feasible to obtain and result in more information about long-term vegetation recovery post-fire.

Technical Abstract: As wildland fire frequency increases around the globe, increased understanding of plant community recovery in burned landscapes is needed to improve effectiveness of rehabilitation efforts. We measured establishment of seeded species, colonization of Bromus tectorum L. (cheatgrass), and recovery of non-seeded native species in topographically distinct areas within five fires that burned Great Basin shrub-steppe communities in Elko County, Nevada. Plant density, frequency, and cover data was collected annually for four years post-fire. Vegetation composition changed significantly in the short distance separating flat areas, north, and south facing aspects. Bromus tectorum was more likely to establish on south aspects, but densities increased steadily on north aspects and in flat areas, and by the fourth year of monitoring, B. tectorum densities within a site were equivalent among topographic features. Non-seeded native perennial grasses, forbs, and shrubs were more likely to be present on north aspects and flat areas, while seeded species were more likely to establish in flat areas. Over time, non-seeded perennial grass densities remained relatively constant, while non-seeded forbs and shrubs increased. In contrast, the density of seeded perennial grasses, forbs, and shrubs decreased over time. For both seeded and non-seeded perennial grasses, plant density in 2007 was a good predictor of density in future years, thus yearly monitoring might not be required to quantify post-fire recovery. Bromus tectorum density in 2007 also predicted the density of B. tectorum in future years, but not as strongly as for perennial species. Frequency measurements were highly correlated with density measurements, especially for perennial, non-rhizomatous species. Our results emphasize the value of considering aspect and the potential for native regrowth when planning and monitoring restorations. Tailoring revegetation objectives, seed mixes, seeding rates, and monitoring efforts to conditions that vary within sites may lead to more cost effective and successful restoration.