Native
And
Prairie Restoration
Site-Preparation And Seeding Information Sheet
Prepared
by Lynda Boyer
Restoration
Biologist and Native Seed Manager
Heritage
Seedlings Inc.
www.heritageseedlings.com
September
29, 2004 (updated August 26, 2005)
Note: These are
techniques that I, personally, have tried. For a full list of a variety of site
prep and seedling techniques, please see the first reference at the end under
“Additional Resources” in Appendix A.
1) Remnant prairie with a good native
component
2) Meadow with a good native component
3) Meadow with only a few natives
4) Uncultivated old fields and pasture with
no natives
5) Cultivated agricultural field
6) Highly disturbed
(excavation, logging etc)
7) Steep areas
where erosion is a concern
(1 or 2)You
need to tiptoe around the natives and only use herbicide in weedy areas with
few or no natives. These areas can be planted with plugs of native plants in
the fall, or seeded if the area is free of major weeds. In the native rich
areas, you can spot-spray weeds or use mechanical control methods such as
weed-eaters, pruners or hand-pulling.
(3) You must decide if it's OK to lose the few
native species you have and then try to reestablish them from seed. For
example, many of our old fields have yarrow and buttercup but little else;
since these species are commercially available, you can focus your efforts on
preparing a site substantially reduced of weeds, and re-seed them.
(4 and 5) Use
herbicide (glyphosate) for AT LEAST two seasons to kill existing vegetation. This
should be applied as soon as you can get into the site. Suggested rate is 1 – 1.5%
glyphosate and 0.25-0.5% surfactant. Herbicide should be applied fall, early
spring, summer, and fall at a MINIMUM. Please, no tilling! Many grasses will be killed in one season;
however, many of our deep-rooted or rhizomatous forbs such as Queen Anne’s
lace, perennial vetch, St. John’s-wort, and clover take more than one season to
control. In addition, hard-seeded species
and annuals such as crane’s bill, mustard, and speedwell will take advantage of
the newly opened space and become flush the second season. Timing of the herbicide application is
crucial. It is desirable to eliminate
each suite of weeds prior to flowering.
Note: Cultivation is not necessary in the age of
no-till drills. Tilling only brings weed seed continually to the surface and
you will NEVER, EVER, EVER, exhaust the weed seed that has built up in the soil
for generations.
A recent
Restoration site-preparation forum hosted by the Lane Council of Governments
and attended by restorationists, researchers, water and soil scientists, and
farmers concluded that the best way to prepare a pasture or agricultural field
for native prairie seed reintroduction is herbicide application for at least two
years without cultivation. Or, if you must till, do it ONLY ONCE and
start the herbicide regime. If baresoil is a concern, plant a cereal cover crop
such as wheat, oats, or barley in September to control erosion and suppress
weeds. According to The Oregon State
Extension Service (see Appendix A Below) cover crops “protect the soil surface,
smother weeds, ….and scavenge nitrogen from the soil before it is leached below
the root zone by winter rains”.
It is important
to look at each site realistically and realize the weed seed bank is bigger
than you are and that it will never be exhausted. The seed drill will invariably dredge up weed
seed no matter how “clean” it may seem post-herbicide application. In uncultivated old fields and pasture,
aggressive, non-native grasses such as bentgrass, tall oatgrass, and
velvetgrass can be the long-term competitive issue for successful native plant
reestablishment. In cultivated fields,
the long-term issue is often broadleaf weeds.
(See Seeding Options below for herbicide strategies depending on
existing vegetation).
Many native
species (both grasses and forbs) are very slow to establish. They need a site
free of other vegetation in order to germinate unimpeded and to mature. Most
bunchgrasses and perennial forbs grow slowly and don't set seed until their
second season (some forbs not until the third.) They are also poor competitors.
Once the prairie is established, it is critically important to burn the site
every 3 – 5 years. If you can't burn, mow. Burning, however, is the most
effective tool to maintain native prairie. Willamette Valley Prairie species
evolved with fire. Fire reduces the competition from thatch and woody species
and stimulates the root crowns of the native grasses and forbs. Burning may
also discourage the non-native grasses and forbs that did not evolve with
fire. Burning every year is not
recommended because it increases the abundance of weedy annual species and
noxious thistles. It may also be necessary to continually augment the area with
new native seed and/or plants after burning or mowing to try and tip the
balance to a sustainable native stand.
During the
first growing season, it may be necessary to spot treating noxious weeds with
herbicide or hand-pulling. It is more
advantageous to target perennial broadleaf weeds such as
(6) If the
site has been disturbed by earthmoving it is absolutely essential to not let it
lay fallow during the winter. Both erosion concerns and the tendency of weeds
to occupy bare soil emphasize the need to sow something on the site as
soon as possible. If the desire is to re-vegetate the site with native plant
species, try to allow any weed seeds that might be present to germinate and
then spray them with glyphosate. Species to be sown should be fall and/or
winter germinating grasses and forbs that compete well with non-native species.
This ensures that they 1) establish prior to erosion problems; 2) they occupy
the spot before fall and winter weeds establish; and 3) they can compete with
any non-native species that may still be present on the site. For suggested
species, see option 3 below.
(7) Since native species are extremely small, even
those that germinate in the fall or winter, it might be advantageous on
erodable sites to first sow a nurse crop of a spring cereal grain. Sow the spring grain early so it will winter
kill, then oversow the area in October with the native seed crop. The native grasses sown should only be low
bunchgrasses that do not flower the first year (Roemer’s fescue, Koeleria
macrantha, Poa secunda, Danthonia californica) so the barley can
be mowed at a height of 6-8 inches. The
grain can be drilled at a moderate rate and, perhaps, on wider spacing than the
native seed. This should ensure little
competition from the nurse crop. Barley
has been recommended due to its lack of regrowth if mowed. This would be necessary if the barley does
not winter kill. Mowing when the barley
is just starting to flower will also reduce the chance of regrowth.
If the site is clean of
weedy forbs but non-native grasses are still a problem (common in old fields,
meadows, and pasture), seed native forbs only the first year, then overseed
with native grasses. This will allow
additional growing seasons where grass-specific herbicides such as Poast® or
Envoy® can be applied.
After the first stand
is established, burning or mowing the site prior to the second native seed application
is a good method for opening up the site.
For drilled seed, the suggested sowing rate is 7 – 9 lbs/acre for grasses
and 4-5 lbs/acre for forbs. For seed that is broadcasted or hydroseeded this
rate should be doubled (this allows for seed predation, and loss due to
erosion, desiccation, and poor soil contact). Seed size should be taken into
consideration with higher rates used for large seeds and lower rates for small
seeds. Seed mixes can be calculated to take into account the seeds/lb of
species desired. Drill seed to a maximum
depth of ¼”. Mulching is not recommended for drilled seed due the necessity of
light for most native prairie species to germinate. For broadcast seed, light
mulch may be applied but it must be weed free!
wp = wet prairie; up = upland prairie; w = woodland
|
Species |
Annual
or Perennial |
Common
Name |
|
Grasses, Sedges, Rushes |
||
|
Carex
tumulicola (up) |
P |
Foothill
sedge |
|
Danthonia
californica (up, wp) |
P |
|
|
Deschampsia
cespitosa (wp) |
P |
Tufted
hairgrass |
|
Elymus
glaucus (up, wp) |
P |
Blue
wildrye |
|
Elymus
trachycaulus (Agropyron caninum) (up) |
P |
Slender
wheatgrass |
|
Festuca
californica (w, up) |
P |
|
|
Festuca
roemeri (up) |
P |
Roemer’s
fescue |
|
Juncus
tenuis (wp) |
P |
Slender
rush |
|
Koeleria
macrantha (up) |
P |
Srairie
junegrass |
|
Luzula comosa (L. campestris) (up) |
P |
Woodrush |
|
Poa secunda (P. scabrella) (up, wp) |
P |
Pine
bluegrass |
|
Forbs |
||
|
Achillea
millefolium (up, wp) |
P |
Yarrow |
|
Agoseris
grandiflora (up) |
P |
Large-flowered
agoseris |
|
Allium
amplectens (wp) |
P |
Slim-leaf
onion |
|
Allium
accuminatum |
P |
Taper-tip
onion |
|
Aquilegia
|
P |
Columbine |
|
Asclepia
speciosus (up, wp) |
P |
Showy
milkweed |
|
Aster
hallii (up, wp) |
P |
Hall's
aster |
|
Aster
subspicatus (w) |
P |
|
|
Balsamorhiza
deltoidea |
P |
Balsamroot |
|
Brodieae
coronaria (up, wp) |
P |
Harvest
brodieae |
|
Calochortus
tolmiei |
P |
Cat’s
ears |
|
Camassia
leichtlinii (up, wp) |
P |
Leichtlin's
camas |
|
Cammasia
quamash (wp) |
P |
Common
cammas |
|
Castilleja
tenuis (Orthocarpus hispidis) (wp) |
A |
Hairy Owl
clover |
|
Clarkia
amoena (up, wp) |
A |
Farewell
to spring |
|
Clarkia
purpurea ssp purpurea (up) |
A |
Purple
godetia |
|
Clarkia
rhomboidea (up) |
A |
Rhombic-petaled
clarkia |
|
Collinsia
grandiflora (up, wp) |
A |
Large-flowered
blue-eyed mary |
|
Collomia
grandiflora (up) |
A |
Large-flowered
collomia |
|
Delphinium
menziesii (up) |
P |
Menzie’s
larkspur |
|
Delphinium
oreganum (up) |
P |
|
|
Dichelostemma
congestum (Brodieae
congesta) (up) |
P |
Ookow |
|
Dodecatheon
hendersonii (up, w) |
P |
Broad-leaved
shooting star |
|
Dodecatheon
pulchellum (wp) |
P |
Few-flowered
shooting star |
|
Eriophyllum
lanatum (up, wp) |
P |
|
|
Erythronium
oregonum (up) |
P |
Fawn lily |
|
Geranium
oreganum (up) |
P |
|
|
Gilia
capitata (up) |
A |
Blue
field gilia |
|
Iris
tenax (up) |
P |
|
|
Ligusticum
apiifolium (up) |
P |
Licorice
root |
|
Lomatium
dissectum (up) |
P |
Fern-leaved
lomatium/biscuit root |
|
Lomatium
nudicale (up) |
P |
Bare stem
lomatium/biscuit root |
|
Lomatium
utriculatum (up) |
P |
Spring
gold |
|
Lotus
micranthus (up) |
A |
Small-flowered
deervetch |
|
Lotus
unifoliolatus (L.
purshianus) (up, wp) |
A |
Spanish clover |
|
Lupinus
albicaulis (up) |
P |
Sickle-keeled
lupine |
|
Lupinus
bicolor (up) |
A |
Small-flowered
lupine |
|
Lupinus
polyphyllus (wp) |
P |
Large-leaf
lupine |
|
Madia
elegans (up) |
A |
Showy
tarweed |
|
Madia
gracilis (up) |
A |
Common / grassy
tarweed |
|
Perideridia
oregana or P.
gairdneri (up, wp) |
P |
Yampah |
|
Potentilla
glandulosa (up) |
P |
Slicky
cinqufoil |
|
Potentilla
gracilis (up, wp) |
P |
|
|
Prunella vulgaris var. lanceolata (up, wp) |
P |
Self-heal |
|
Psoralea
physodes (up) |
P |
Scurf pea |
|
Ranunculus
occidentalis (up) |
P |
Western
buttercup |
|
Sanguisorba
occidentalis (up, wp) |
A |
Western
burnet |
|
Sanicula
bipinnatifida (up) |
P |
Purple
sancicle |
|
Sidalcea
campestris (up) |
P |
Meadow
checker mallow |
|
Sidalcea malviflora ssp. virgata (up) |
P |
Rose
checker mallow |
|
Silene
hookerii (up) |
P |
Hooker’s
silene |