Post-fire remediation actions, specifically hydraulic mulching and seeding, have a detrimental impact on the re-establishment of natural plant communities in California.
Point of View:
One of the first questions asked following an urban wildfire is whether or not to seed hillsides left barren by the fire and subject to erosion. Prior to 1993, the practice in California, as in other parts of the world, was to apply aggressive seed mixtures by helicopter with the intent of establishing quick-growing, erosion control cover. Whether or not this practice is effective is still open to research and debate. An extension of this discussion has been whether or not certain types of seeds, most notably annual ryegrass, should be included in any reclamation seed mixture. Studies have shown that Lolium appears to inhibit emergence of shrub seedlings , yet there is little data on whether or not seeding with ryegrass alone is effective in controlling erosion .
Most people equate hydraulic applications with seeding and the use of invasive, non-native species like ryegrass. The reality is that since the East Bay Fire of 1991 it appears that none of the seed mixtures employed in California since 1991 have contained any ryegrass. Instead, zorro annual fescue (Vulpia myuros) has sometimes been substituted for the quick-growth component in seed mixtures. The trend in recent years has been to use as little seed as possible, or none at all, to allow viable seed and roots of indigenous plant to re-establish themselves over time. This practice in itself is controversial in that some scientists suggest that little to no seeding after fires offers weed species the opportunity to become established at the expense of the native plant population.
These preceding perceptions sometime result in public apprehension that current remediation techniques inhibit the natural course of plant regeneration and therefore the long term stability of fire-affected areas. It is often suggested that (1) reclamation seed mixtures affect the re-establishment of native species; (2) temporary erosion control methods... such as the use of hydraulic application measures… adversely affect introduced as well as indigenous plant growth; and that (3) the combination of introduced seeds and temporary mulching practices adversely affect the vegetative diversity of a recovering burned site. But at this time there appears to be no current research that supports any of these conclusions or provides guidance to those in the field tasked with making informed decisions.
Finally, much of the difference of opinion concerning the effects of post-fire remediation activities on the recovery of vegetation continues to be fueled by the lack of funding for basic research. In the United States, the Department of Homeland Security/Federal Emergency Management Agency (FEMA) appears to be effective in funding the temporary, post-fire reclamation practices, but not the long-term operation, maintenance and monitoring of those practices. Most research to date has been conducted by the U.S. Forest Service on their fire-affected land and not in those areas along the urban interface where these questions need to be addressed.