Revegetation of Weed-Infested Plant Communities

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Revegetation of Weed-Infested Plant Communities

• Jane Mangold
• Extension Invasive Plant Specialist

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Begin with the end in mind. . .

• Kill the weedYes, but not the whole story
• Healthy plant community that meets management
  objectives

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Vicious (and Frustrating) Cycle
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Traditional Weed Management
Herbicides
Biocontrol
Hand-pulling
Revegetation
WEED
Grazing
Fertilization
Prevention
Fire
Tilling/disking
Mowing
Irrigation
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Future Management
Biocontrol
Herbicides
Hand-pulling
Revegetation
Grazing
Life cycle of weed
Plant Community
Desired Vegetation
Prevention
Fertilization
Fire
Tilling/disking
Irrigation
Mowing
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What can we do to cause this?
What caused this?
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Necessary Components for Plant Community Change
Plant Community Undesired State
Site Availability
Species Availability
Species Performance
Plant Community Desired state
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Managing Plant Communities
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Step 3 Assess Soil and Site Properties Are they
acceptable?
yes
Step 2 Determine Necessity of Revegetation
If unsure, contact local
Extension, weed coordinator, NRCS, or
Conservation District office and schedule a site
visit. Is revegetation necessary?
Step 1 Make a Goal Statement Describe desired
condition.
Can soil be amended or are species available that
are adapted to the soil?
no
yes
yes
no
no
Step 4 Site Preparation Consider
seedbed preparation and/or soil amendments.
Stop Revegetation is not recommended.
Stop Allow natural recovery. Monitor frequently
to identify and rectify problems.
Step 7 Determine Seeding or Planting Method
Is site accessible to equipment?
12 step program for reducing chemical control
dependency
Step 6 Design Seed Mix Create seed mix
based on goals and site characteristics. Is the
site a natural area?
no
Are invasive weeds a problem at the site?
Use native species to provide ecological
stability and maintain plant community integrity.
Step 5 Reduce Weed Interference Methods vary
depending on many factors.
yes
yes
yes
no
no
Always use native species when their abilities
meet your needs. Non-natives are sometimes the
only choice when needs are based on
considerations like forage production and
competitiveness with invasive weeds.
Step 11 Monitor Monitor
establishment to identify and rectify problems in
time to allow successful revegetation.
Step 12 Long-Term Management Carefully manage to
favor seeded species.
Step 10 Assist Establishment May include actions
that precede or immediately follow
seeding/planting.

• Hydroseed sloped sites
• Roughen soil surface before and after broadcast
  seeding and apply hydromulch
• Hay mulch seed
• Plant rhizome sprigs in high- salinity sites.

Step 8 Calculate Seeding Rate Rates vary
depending on many factors.

• Broadcast seed a non-prepared seedbed at double
  to triple seeding rate
• Hand-plug wetland/riparian plants.

Step 9 Determine Best Time to Seed
Indicated by selected species, method of
planting, and soil texture.
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Step 1Make a goal statement
difficult

• Revegetation
• Returning vegetation to a site little emphasis
  on amending ecological function
• Rehabilitation
• Returning a site to a functioning state, but not
  necessarily its original state
• Native species not required
• Restoration
• Returning a site to its original, functional
  state
• Native species are required

very difficult
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Assisted Succession

• Restoration of weed-infested rangeland may
  require multiple steps

Cheatgrass/ annual forbs
Introduced, competitive grass
Native vegetation
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Example Goal Statements

• Short-term goals
• At the end of YR1, reduce weed cover by 25 and
  increase desirable grass and forb cover by 25.
• Mid-term goals
• At the end of YR5, reduce weed cover to lt20 and
  increase desirable grass and forb cover to gt50.
  Hand-pulling and or spot treatment is used to
  control weeds.
• Long-term goals
• At the end of YR10, weeds occur only infrequently
  (controlled by hand-pulling) and site is
  dominated by desirable grasses and forbs.

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Step 2Determine if revegetation is necessary

• Sites with gt20-30 canopy cover of desired
  vegetation can usually recover naturally if
  performance of weeds is hindered

Canopy cover area of ground covered by plant
foliage
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Step 3Assess soil and site properties

• Assess soil properties to determine if they are
  acceptable or can be feasibly amended

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Soil Properties
Soil parameter Ideal condition Acceptable range My soil Acceptable? Yes or No
Bulk density (gm cm-3) 1.4 1.2-1.6
Soil texture (sand, silt, clay) Loam Clay loam to sandy loam
SalinityEC (mm/hos/cm soluble salts) 0-2 lt8
Organic matter () gt3 gt2
pH 6.5-7.5 5.5-8.5
SAR (NaCaMg) lt6 lt12
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Site Properties

• Precipitation
• Temperature
• Elevation
• Aspect
• Soil moisture
• sub-irrigated
• dry, upland

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Step 4Prepare site

• Seedbed
• Firm enough to allow good seed-soil contact
• Loose enough to allow seed to sprout and
  penetrate soil
• Preparation depends on seeding method
• Usually not necessary for drill seeding
• Highly recommended for broadcast seeding

Its all about balance!
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Site Preparation

• Compacted soil (high bulk density)
• Limits air exchange, water infiltration, and
  number of safe sites
• Scarify, till, disk, or plow

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Site Preparation

• Chiseling or harrowing
• Plowing
• Disking
• Dragging small chains
• Limit the amount and intensity of disturbance!
• Weed like disturbance!

Do so shallowly to avoid nitrogen release
disked stripsnotice brown, cured cheatgrass
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Site Preparation

• Herbicide application
• Burning
• Imprinter

Create safe sites
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Site Preparation - Soil
Amendments

• Fertilizer is typically not necessary
• Organic matter
• May also decrease nitrogen availability
• Mycorrhizal innoculants

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Step 5Reduce Weed Interference

• Herbicides
• Mowing
• Grazing
• Biocontrol
• Cover crop
• Late season herbicide application combined with
  fall dormant seeding (single entry revegetation)

Do for a couple years prior to seeding to weaken
weeds
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Herbicide Selectivity

• Non-selective
• Kills/stresses any plant
• E.g. Roundup, Journey
• Selective
• Affects some plants, but not all
• Tolerance varies from species to species
• E.g. 2,4-D, Tordon, Transline, Milestone, most
  range and wild land herbicides

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Herbicide Selectivity

• Roundup
• Tordon
• 2,4-D
• Plateau
• Transline
• Milestone

• NONE
• MODERATE
• MODERATE
• MODERATE to HIGH
• HIGH
• MODERATE

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Single Entry Revegetation
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Single Entry Revegetation

• Tested on Russian knapweed in eastern OR

Control plot
Single entry revegetation plot
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Step 6Design seed mix

• Avoid pre-made mixes from unknown or far away
  sources!

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Step 6Design seed mix

• Customize to meet goals
• Forage production
• Minimize erosion
• Minimize weed invasion and re-establishment
• Restore a healthy and diverse plant community
• Customize to site conditions
• Soil properties (e.g. texture, salinity)
• Precipitation, temperature, elevation, aspect,
  soil moisture

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Seed Mixes

• Functionally diverse
• Grasses
• Forbs
• Shrubs
• Species-rich
• Productive
• Weed-free, quality seed

Increased resource capture and reduced risk of
re-invasion
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Step 7Determine planting methods

• Drill
• Most often preferred
• Broadcast
• Steep, rocky, or remote sites
• Hydroseed
• Slopes 31 or steeper
• Hay-mulch
• Spread hay containing seeds over prepared seedbed
• Island seeding

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Drill Seeding

• Seed depth and rate are closely controlled
• Good seed-to-soil contact
• Shortcomings
• Rows look unnatural
• Long, narrow seeds may become lodged in seeder
• Species require placement at different depths
• Seeds of different sizes separate in boxadd
  carrier such as cracked corn or rice hulls
• Drill furrows can enhance erosionseed along
  contour

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Island Seeding
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Distance to Recruit Patches
Reever Morghan et al. 2005. Ecological
Restoration 23(3)214-215
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Step 8Calculate seeding rate

• Typically 20-50 seeds/ft2
• Determine rate based on pure live seed (PLS)
• Determine rate based on seeding method and
  situation
• Increase rate 2-3x for broadcast seeding
• Increase 2-3x for weed-infested areas
• Adjust individual species rates according to its
  desirable proportion of the mix

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Pure Live Seed (PLS)

• Measure used by seed industry to describe the
  percentage of a quantity of seed that will
  germinate
• PLS purity X viability
• Standardizes quality so puchaser can compare
  quality and value of different seed lots

100
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Read the label!
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Do the math!

• Lower /lb., but lower purity and viability
  buying more seed to achieve target seeding rate
• Higher /lb., but higher purity and viability
  buying less seed to achieve target seeding rate

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Step 9Determine best time to seed

• Cool season species
• Fall-dormant during late fall
• Riparian plugs
• Warm temperatures, long days, adequate water
• Late summer planting only if supplemental water
  is available

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Step 10Assist establishment

• Seedling establishment is most vulnerable stage
  of revegetation program
• Implement management to protect sensitive
  seedlings
• Supplemental irrigation
• Defer grazing
• Mulch

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Step 11Monitor progress

• Identify and fix problems in time to allow for
  success
• Level of monitoring increases with severity of
  site conditions

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Step 12Long-Term Management

• Tailor management to maintain developed plant
  community
• May include
• Multi-species grazing
• Allowing low-intensity disturbance, e.g. fire,
  proper grazing
• Controlling re-establishing weeds

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Plant Community Undesired State
Site Availability
Species Availability
Species Performance
Plant Community Desired state
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Information adapted from
Revegetation Guidelines for Western Montana
Considering Invasive Weeds by K. Goodwin, R.
Sheley, and J. Marks Montana State University
Extension Bulletin 170 http//msuextension.org/pub
lications/AgandNaturalResources/EB0170.pdf 3/copy
from Extension Publications (994-3273)
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Questions? Thank you!

• For more information
• EB0019 Dryland Pastures in Montana and Wyoming
  http//msuextension.org/publications/AgandNatural
  Resources/EB0019.pdf
• Jane Mangold, Extension Invasive Plant Specialist
• 994-5513 jane.mangold_at_montana.edu

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Plant Communities Always Change (Succession)

• Process whereby one plant community changes into
  another. It involves the immigration and
  extinction of species, coupled with changes in
  the relative abundance of different plants.
• -Plant Ecology by M.J. Crawley

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Initial Plant Community
Site Availability
Species Performance
Species availability
Final Plant Community
Biological control
Biological control
Herbicide
Grazing
Repeated Spring Grazing
Revegetation
Tilling
Grazing
Hand pulling
Hand pulling
Fire
Fertilization
Mowing/cutting
Herbicide
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Tilling improved establishment of seeded species
in Russian knapweed infestation
Mangold et al. 2007
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Sheley, R. 2007. Weed Science 55365-370
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Competitive Effects of Seeded Grasses
Seeding Treatment Perennial Grass Biomass (kg/ha) Cheatgrass Biomass (kg/ha) Reduction
Critana thickspike wheatgrass 792 913 32
Bozoisky Russian wildrye 900 737 45
Sodar streambank wheatgrass 1135 207 85
Luna pubescent wheatgrass 1714 0 100
Hycrest crested wheatgrass 1596 124 91
Unseeded control --- 1337
Whitson and Koch 1998