Prescribed Fire and Tobosagrass Community Response

Tobosagrass is a a climax species on bottomland range sites in the Chihuahuan Desert and is considered a highly productive livestock forage, especially after disturbance and as a reserve feed during drought years.  We examined the potential beneficial effects of prescribed fire on a tobosagrass community where the historically typical disturbance represented by wildfire has been suppressed in modern times.  Disturbance by grazing on the research site was also nearly absent because of low stocking rates.  Of particular interest to us was the response in terms of species diversity, since higher diversity is normally indicative of a healthier ecosystem, and increases in forb species are important as wildlife forage.

We sampled vegetation before and after prescribed burns on three sites on a ranch in Brewster County and compared the response in terms of tobosagrass cover and species richness to that on two unburned sites.

In the short-term, increases in bare ground in the burned areas were significant, and landowners and managers must be attentive to this reality in order to monitor the potential for erosion.  Burning with sufficient soil moisture for immediate growth post fire can help mitigate the impact of canopy loss.
However, in the long-term (several months post-burn) tobosagrass canopy and basal cover regenerated, but were reduced from pre-burn levels.  This is seen as a positive benefit in terms of livestock forage given that overgrown tobosagrass is of lower nutritive value than that at earlier growth stages.  Additionally, species richness, including forbs, increased across all burned sites.

Our findings indicate that prescribed fire can be successfully used as a management tool to reduce high fuel loads in tobosa grasslands, increase forage for both livestock and wildlife, and to increase species richness.

Prescribed fire on a tobosagrass flat on a ranch in Brewster County.

 

grassland

The same area following recovery.