Monday, March 14, 2016

Fire

"Where there is smoke, there is fire." -Unknown

Ephedra californica, this shrub may be a a good candidate for use in post-fire restoration efforts in desert areas due to its quick growth rate. Photo by Stan Shebs

Historically in desert systems, fire has been remarkably limited. There is separation between plants which makes fire difficult to spread under historic conditions.

However, with an increase in invasive, fast growing vegetation; fires have increased in the last hundred years in desert systems.

These fires can drastically alter arid systems and kill native vegetation. Additionally, they can alter soil characteristics which make it tougher for native vegetation to re-emerge. In many cases, post fire species composition in deserts shows high dissimilarity from species compositions pre-fire. These divergences don't seem to be temporary either, with many studies suggesting that there are significant difference between before and after fire species compositions even nearly 50 years after the last time an area was burned. Fire can also change soil dynamics significantly, making it hard for cryptobiotic soil crusts to recolonize.

Fires can also result in a positive feedback loop which benefits non-native, often fire adapted plants. Making it harder for native plants to recolonize and easier for non-native ones to do so. The communities that exist after desert areas have been burned rarely bear resemblance to their former selves.

The Creosote Bush, Larrea tridentata, common in most of the North American desert region is unlikely to recolonize an area following a fire. Photo by wikimedia user Sue in az.


Invasive species management in deserts is an important way that we can reduce risk of fire in areas which often evolved without it. Removing invasive grasses such as cheatgrass, buffelgrass, and red brome is especially important to preserving intact desert plant communities which makes it an important management goal for arid land conservation.

The North American deserts have only been around for several thousand years based on climatic data, so change is not new to the region. However, the fact that seemingly small human caused changes, such as introduction of one species of non-native grass, can drastically alter plant and animal communities for half a century, may force us to answer important questions about why we value desert communities and what aspects of their biological integrity are most important to preserve.




References and further reading:


Abella, Scott R. "Post-fire plant recovery in the Mojave and Sonoran Deserts of western North America." Journal of Arid Environments 73.8 (2009): 699-707.

Brooks, Matthew L., and David A. Pyke. "Invasive plants and fire in the deserts of North America." Proceedings of the invasive species workshop: the role of fire in the control and spread of invasive species. Fire conference. 2000.

Johansen, Jeffrey R., et al. "Recovery patterns of cryptogamic soil crusts in desert rangelands following fire disturbance." Bryologist (1984): 238-243.

 Sara J. Scoles-Sciulla , Lesley A. DeFalco & Todd C. Esque (2015) Contrasting Long-Term Survival of Two Outplanted Mojave Desert Perennials for Post-Fire Revegetation, Arid Land Research and Management, 29:1, 110-124.

No comments:

Post a Comment