Revegetating After Wildfires
Loss of vegetation leaves land vulnerable to increased runoff, erosion, and
sedimentation; encourages weeds; degrades habitat; and impairs forest
regeneration. Revegetation is a good step to take toward controlling noxious
weed invasion after a wildfire. For more information about weed suppression, you
could also contact your county weed coordinators. Reestablishment of permanent
vegetation provides long-term erosion control, protection, and site stability.
This practice is the least expensive per acre. It directly addresses the
resource concerns, and it is best suited to addressing concerns over larger
areas.
What Areas Need Revegetating?
In general, severely and moderately burned sites should be reseeded to
decrease the likelihood of erosion and sediment movement down slopes, to
discourage weed invasion, and to fulfill management objectives. Since lightly
burned areas recover quite quickly from wildfire, reseeding is usually not
necessary.
When Should I Plant?
Grasses and forbs should be planted after the wildfire or ground disturbance
when the soil surface is loose. Seeding in late fall or winter (even if there
are a few inches of snow) improves success. The prime time to seed is
immediately prior to the ground freezing. Trees or shrubs should be planted in
the fall or early spring when plants are dormant.
What Should I Plant?
Perennial grasses and forbs are slower to establish, but provide long-term
cover for reseeded sites. Sites to revegetate with perennial grasses and forbs
include severely burned sites and moderately burned sites that had populations
of noxious weeds before the wildfire or that are less than 50 feet from a
drainage channel. For example, slender wheatgrass is a native grass that
establishes quickly and is moderately long-lived. Over time, as the slender
wheatgrass begins to die out, other native species begin to fill in the site.
Annual ryegrass and small grains are useful when quick establishment is key;
however, they only provide one year of protection. Revegetate with annual
species where perennial grasses will recover naturally, including moderately
burned sites with slopes greater than 15 percent. For example, winter wheat is a
good option if native seed varieties are unavailable.
How Much Should I Plant?
Most seedings are broadcast with either aircraft or ground equipment.
Landowners can seed small areas using a hand-crank seed broadcaster. You should
use certified seed of a known variety to get the best results. If a specified
variety is not available, be sure the seed originated within a 500-mile radius
of your property. Be sure seed does not contain any noxious weeds. Contact the
local NRCS, Extension Service, or conservation district office for recommended
varieties or substitute species.
The seed mixes in the following charts are appropriate for areas west of the
Continental Divide and foothills/mountains east of the Divide. Ideally, you
should choose one to three of these species for a mix. The tables give the
“pure-stand” seeding rates for each species expressed as pounds of pure live
seed (PLS) per acre. To calculate a mix, divide the species rate by the number
of species in the mix. Then, take the lbs/ac and multiply by the total acres to
be seeded. Double these seeding rates on severely burned areas or steep slopes.
For example, if you are using a mix of three grasses to be seeded on 10
acres, divide the lbs/ac for each species by three and then multiply by 10. For
slender wheatgrass the equation would be (12/3)10 = 40 pounds of slender
wheatgrass in the mix.
Is There Anything Else I Can Do to Help the Planting?
Mulching will stabilize the soil surface to prevent movement of soil
particles and loss of seed. Use straw or grass hay mulch or netting on small
areas of steep slopes. Apply mulch at 70 lbs/1,000 sq. ft. (about 43 bales per
acre). Use weed free material. Do not fertilize the first year. Hydromulching
should be done in two operations. First, use a mulch-seed mixture to distribute
the seed. Then, use the remaining mulch over the top to increase contact of
seeds with the soil.
Keep your work well-maintained by repairing any spots of failure with new
seed, plants, and mulch. Fertilize after the first year in spring until
vegetation is well established.
What Seeding Rates Should I Use?
Zone 1
Zone 1 is made up of dry, warm sites consisting of open grasslands and
woodland benches at low elevations on all aspects and on south and west-facing
slopes at higher elevations. Woodland sites are dominated by dry Douglas-fir,
limber pine, and ponderosa pine habitat types with a significant bunch grass
component in the understory.
Grass/Forb Species |
Native/Introduced |
Pounds PLS per acre at 40 seeds per square foot |
‘Pryor’ Slender wheatgrass |
N |
12 |
‘Critana’ Thickspike wheatgrass |
N |
12 |
‘Sodar’ Streambank wheatgrass |
N |
11 |
‘Goldar’ Bluebunch wheatgrass |
N |
12 |
‘Sherman’ Big bluegrass |
N |
2 |
‘Manska’ Pubescent wheatgrass |
I |
30 |
‘Covar’ Sheep fescue |
I |
3 |
‘Durar’ Hard fescue |
I |
3 |
Yellow sweet clover |
I |
(no more than 1/2 lb/ac) |
Dryland alfalfa varieties |
I |
(no more than 1/2 lb/ac) |
Zone 2
Zone 2 is made up of moist, warm sites consisting of moderate environments
receiving more effective precipitation than the dry, warm sites. Zone 2 sites
are found on north and east-facing slopes at lower elevations, on all aspects at
mid-elevations, and on south and west-facing aspects at higher elevations. Sites
are dominated by Douglas-fir and ponderosa pine habitat types.
Grass/Forb Species |
Native/Introduced |
Pounds PLS per acre at 40 seeds per square foot |
‘Pryor’ Slender wheatgrass |
N |
12 |
‘Critana’ Thickspike wheatgrass |
N |
12 |
‘Sodar’ Streambank wheatgrass |
N |
11 |
‘Whitmar’ Beardless wheatgrass |
N |
12 |
‘Sherman’ Big bluegrass |
N |
2 |
‘Garnet’ Mountain brome |
N |
22 |
‘Rush’ Intermediate wheatgrass |
I |
22 |
Nevada bluegrass |
I |
2 |
‘Covar’ Sheep fescue |
I |
3 |
‘Durar’ Hard fescue |
I |
3 |
‘Paiute’ Orchardgrass |
I |
4 |
White Dutch, red, or white clover |
I |
2 |
Yellow sweet clover |
I |
(no more than 1/2 lb/ac) |
Alfalfa |
I |
(no more than 1/2 lb/ac) |
Zone 3
Zone 3 is made up of moist, cool sites. Zone 3 sites are found predominantly
on north and east-facing slopes at mid-elevations and on all aspects at high
elevations. Sites are dominated by Douglas-fir with blue huckleberry in the
understory along with Grand fir, western cedar, and western hemlock habitat
types.
Grass/Forb Species |
Native/Introduced |
Pounds PLS per acre at 40 seeds per square foot |
‘Pryor’ Slender wheatgrass |
N |
12 |
‘Whitmar’ Beardless wheatgrass |
N |
12 |
‘Sherman’ Big bluegrass |
N |
2 |
Tufted hairgrass |
N |
1 |
‘Garnet’ Mountain brome |
N |
22 |
‘Rush’ Intermediate wheatgrass |
I |
22 |
‘Paiute’ Orchardgrass |
I |
4 |
‘Covar’ Sheep fescue |
I |
3 |
‘Durar’ Hard fescue |
I |
3 |
Nevada bluegrass |
I |
2 |
Alsike, red, or white clover |
I |
(no more than 1/2 lb/ac) |
Birdsfoot trefoil |
I |
(no more than 1/2 lb/ac) |
Zone 4
Zone 4 is made up of riparian areas including stream
bottoms and wet meadows. These sites are subirrigated or wetter for at least a
portion of each growing season.
Grass/Forb Species |
Native/Introduced |
Pounds PLS per acre at 40 seeds per square foot |
‘Pryor’ Slender wheatgrass |
N |
12 |
Basin Wildrye |
N |
2 |
Meadow foxtail |
I |
2 |
Birdsfoot trefoil |
I |
(no more than 1/2 lb/ac) |
Alsike clover |
I |
(no more than 1/2 lb/ac) |
![Photo of a helicopter picking up another load of seed.](https://webarchive.library.unt.edu/eot2008/20090109053859im_/http://www.mt.nrcs.usda.gov/technical/images/wildfire/seeding1.jpg)
More than 5,200 acres of private land were aerial seeded with slender
wheatgrass in the Bitterroot Valley during 2000. Aerial grass seeding was very
successful in most cases.
![Photo of a crew hydromulching a hillside behind a home.](https://webarchive.library.unt.edu/eot2008/20090109053859im_/http://www.mt.nrcs.usda.gov/technical/images/wildfire/seeding2.jpg)
Some areas, such as stream banks and slopes around homes, were also
hydro-seeded to provide immediate cover.
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