By Tery Susman, UC Master Gardener of Mariposa County.
Our human tendency is to fix what we perceive as a potential problem or as something “broken” or “untidy.” Our first thought is to reseed flowering plants and grasses on our fire scorched property to speed up vegetation establishment and soil stability, to fix what is “broken.”
However, recent research has shown that seeding is not more eﬀective than letting the area recover naturally; and given the risk of introducing invasive species, it is generally no longer recommended.
Natural regeneration gives the land a chance to recover on its own from the existing soil seed bank, nearby seed sources, and the resprouting of surviving perennial plants.
The research indicates two important points regarding reseeding grasses following wildfire:
- This management practice is usually not cost-eﬀective.
- It appears to create more problems than it solves.
Potential negative eﬀects of this practice include:
• Seeds of invasive annual grasses like wild oats, ryegrass, and bromes develop shallow root systems that have little to no eﬀect on slope stability.
• Seeding provides marginal eﬀects or results in the first year following fire, or not at all and no significant eﬀect when slower native perennials are the plant of choice in the first year.
• Seeding uses up more ground moisture and reduces regrowth of native plants that regenerate from resident seed bank in the soil.
• Native grass seeding may cause gene pollution of resident native grasses especially if the grasses sowed were of a diﬀerent gene type and collected in other areas of the state.
• Seedings may have long-term negative eﬀects on the ecosystem by changing plant community composition over time.
• Seedbed preparation can cause disturbance to slopes, soil, pre-existing vegetation, and the surrounding seedbank.
• Seeding can give property owners a false sense of security that this one practice will mitigate most post-fire land issues.
Seeding is no longer the recommended practice following a wildfire. However, many experts also agree that for specific erosion control problems, it may be necessary to seed native perennial grass to mitigate these issues.
Potential positive eﬀects of seeding grasses:
• Native or sterile non-native grasses can reduce non-native invasive plant encroachment by competition.
• Seeding can increase infiltration and reduce surface runoﬀ and resulting soil erosion.
• Seeding may be used purposely to reduce shrub regrowth on range and pasture lands.
Before you decide to plant grass seed on wildfire damaged soil and slopes, reach out to Natural Resources Conservation Service (NCRS) for a site-specific evaluation of your post-fire property needs.
The Natural Resources Conservation Service may be reached at 209-966-3431. You may also visit their website at nrcs.usda.gov.wps.portal.nrcs/site/ca/home.
There are distinct reasons that may be addressed by seeding, but in general natural regeneration is the best option. Remember, lands have recovered many times after wildfires.
Once human-made debris is removed, in most cases the land will heal on it’s own. It just takes time!
To seed or not to seed? In most cases the answer is not to seed.
Next: YOU Can Help Prevent Wildfire Spread
UC Master Gardeners of Mariposa County are located at 5009 Fairgrounds Road, Mariposa. For more gardening and event information, visit their website or Facebook page (UC Master Gardeners of Mariposa County).
UC Master Gardeners staff a helpline serving Mariposa County, including Greeley Hill, Coulterville, and Lake Don Pedro. Please contact them at 209-966-7078 or via e-mail at email@example.com.
Listen to them on the radio at KRYZ 98.5 FM on Wednesdays at 2 p.m and Saturdays at 5 p.m.