Effects of fire regime changes and post-fire treatments on dust emission in sagebrush shrublands of the Great Basin, USA

Background/Question/Methods

In rangelands around the world, larger and more frequent wildfires are occurring as a function of climate change and are expected to exacerbate dust emissions and wind erosion, adversely impacting ecological condition. The length of the annual fire season is also increasing in many rangelands and understanding how this fire regime change influences post-fire erosion is critical for minimizing losses in site productivity. Moreover, post-fire seeding treatments are commonly employed to promote soil stability in the short-term and the recovery of a desirable plant community in the long term, yet there are questions regarding their effectiveness. We consider how a longer fire season can impact the length of time that soils are prone to enhanced wind erosion in the context of natural vegetation dynamics relative to drill and aerial seeding in the first year after fire. Methods include analysis of vegetation greenness dynamics (phenometrics) derived from time-series of satellite imagery for 32 large fires with replicate burned-untreated, -drill seeded, and -aerial seeded plots. Methods also include analysis of seeding treatment effects for dust emissions simulated for a chronosequence of vegetation recovery from 89 fires that burned 1990-2010.

Results/Conclusions

Simulations for the longer-term chronosequence of post-fire vegetation recovery did not show differences in potential dust emissions between untreated and seeding treatments during the years-decades after fire. Simulated dust emissions identified a short window of time during the first year(s) after fire that burned surfaces are especially prone to exacerbated emissions. During the first year after fire, results of the phenometrics analysis indicate that the length of time that soils are prone to enhanced dust emission varies with the time of year that fires burn, and suggest the potential for greater soil loss with increased occurrence of early relative to late-season fires. Significant effects of seeding treatments on vegetation dynamics that might enhance soil stability in the first year after fires were not evident. Findings have important implications for the refinement and prioritization of post-fire rehabilitation and soil stabilization efforts that are commonly employed.