Eurasian Watermilfoil - Fraser Basin Council

Understanding
Eurasian Watermilfoil
John D. Madsen
Geosystems Research Institute
Mississippi State University
[email protected]
Cultus & Nicola Lakes Water Quality & Eurasian Watermilfoil Workshop, Fraser Basin
Council, Abbottsford, BC, Canada February 15, 2013
www.gri.msstate.edu
Eurasian watermilfoil
Overview
• Taxonomy and
description
• Distribution
• Habitat
• Ecological range
• Problems
• Propagation and spread
• Growth and phenology
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Benefits of Aquatic Plants
• Stabilize lakes
sediments, reducing
resuspension
• Increase
sedimentation,
reducing turbidity
• Provide habitat for
insects, forage fish,
fish spawning and YOY
fish
• Provide food for
waterfowl, other
animals
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Invasive vs. Native Community
Invasive Myriophyllum
spicatum
Native Potamogeton sp. Mixed
stand
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Eurasian
watermilfoil
• Myriophyllum spicatum L.
• Aquatic family
Haloragaceae
• Forms dense nuisance
surface canopy
• Herbaceous evergreen
perennial
• Spreads by root crown /
runner and autofragment
• Nonnative from Europe and
Asia
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Eurasian watermilfoil Problems
• Nuisance growth
interfering with
recreation
• Human use
impacts
• Ecosystem impacts
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Human Use Impacts of
Eurasian watermilfoil
• Commercial
Navigation
• Hydropower
• Flood Control
• Spread of insectborne diseases
• Recreational
impairment
• Property value
• Human health
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Ecological Effects of Eurasian
watermilfoil
•Degradation of water
quality
•Reduction in species
diversity
•Suppresses native plant
species
•Potential impacts on
endangered species
•Alters animal
communities
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Fall River, CA
Hennepin Lake, IL
Pend Oreille River, WA
Mobile Bay, AL
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Lake Minnetonka, MN
Waneta Lake, NY
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Lake Hortonia, VT
Houghton Lake, MI
Remetrix, Inc.
Taxonomy
• Wholly-aquatic family
Haloragaceae
• Two genera –
Myriophyllum and
Proserpinaca
• Fourteen Myriophyllum
species in the US, twelve
are native
• Four native species are
shown for western North
America
• Two invasive species
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Myriophyllum spicatum
in Vermont
Taxonomy of Myriophyllum
• Despite fifty years of work on Eurasian
watermilfoil in North America, there are
persistent concerns and confusion, even
among professionals, on how to tell
Eurasian watermilfoil from native
watermilfoil species (particularly northern
watermilfoil).
• Recent genetic evidence of hybridization
further exacerbates the confusion
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Myriophyllum species in the US
Scientific Name
Myriophyllum alterniflorum DC
Myriophyllum aquaticum (Vell.) Verdc.
Myriophyllum farwellii Morong
Myriophyllum heterophyllum Michx.
Myriophyllum hippuroides Nutt. ex
Torr. & A. Gray
Myriophyllum humile (Raf.) Morong
Myriophyllum laxum Shuttlw. ex
Chapm.
Myriophyllum pinnatum (Walter)
Britton, Sterns & Poggenb.
Myriophyllum quitense Kunth.
Myriophyllum sibiricum Komarov
Myriophyllum spicatum L.
Myriophyllum tenellum Bigelow
Myriophyllum ussuriense (Regel)
Maxim.
Myriophyllum verticillatum L.
Common Name
Alternate flower watermifloil
Parrotfeather
Farwell’s watermilfoil
Variableleaf watermilfoil
Western watermilfoil
Native or
Nonnative
Native
Nonnative
Native
Native*
Native
Low watermilfoil
Loose watermilfoil
Native
Native
Cutleaf watermilfoil
Native
Andean watermilfoil
Northern watermilfoil
Eurasian watermilfoil
Slender watermilfoil
Russian watermilfoil
Native
Native
Nonnative
Native
Native
Whorl-leaf watermilfoil
Native
Native Myriophyllum
Western Watermilfoil
Myriophyllum hippuroides
Kathy Hamel
Andian Watermilfoil
Myriophyllum quitense
Jenifer Parsons
Northern Watermilfoil
Myriophyllum sibiricum
John Madsen
Whorled watermilfoil
Myriophyllum verticillatum
USDA NRCS
Northern
watermilfoil
Myriophyllum
sibiricum Komarov
Common native in
northern United
States
Occasionally forms a
nuisance
Circumboreal
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Eurasian
watermilfoil
• Myriophyllum
spicatum L.
• Nonnative from
Eurasia
• Widespread
nuisance-forming
invasive (49 US
states, southern tier
provinces of
Canada)
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Morphological
Methods
• Morphological conditions
measured in six segments
of each specimen:
• Stem red or green
• Apical meristem
rounded or flat
• Leaf tips rounded or
flat
• Internode length
• Stem thickness
• Leaf length
• Leaflet length
• Leaflet number
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Northern watermilfoil
specimen from Pend
Oreille Lake, ID
Genetic Methods
•
•
•
•
PCR Amplification
separated by
electrophoresis and
sequenced (BGU)
Phylogenetic analysis
and chloroplast gene
sequencing (GVSU)
PCR-RFLP (MSU)
All three labs used
different approaches,
with some cross-over
verification
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Morphological Results
Comparison of Boolean characteristics of northern watermilfoil and Eurasian watermilfoil, with a
comparison by Fisher's exact test.
Fisher's Exact
Test
Characteristic
Northern watermilfoil
Eurasian watermilfoil
P-value
Flat Leaf End
No
Yes
4.2%
(1)
No
5.6%
(1)
No
Yes
No
Yes
83.3% (20)
16.7% (4)
5.6%
(1)
94.4% (17)
Green
Red
Green
87.5% (21)
12.5% (3)
72.2% (13)
95.8% (23)
Flat Apical Meristem
Stem Color
Yes
94.4% (17)
Red
27.8%
(5)
<0.0001
<0.001
0.256
Morphological Results, cont.
Comparison of morphological characteristics of northern watermilfoil and Eurasian watermilfoil, with
a comparison by T-test
Northern watermilfoil
Variable
Eurasian watermilfoil
T-test
Mean
SE Mean
Mean
SE Mean
p-value
Leaflet Number
8.10
0.123
16.32
0.253
<0.0001
Leaf Length (mm)
20.0
0.420
18.07
0.415
0.001
Leaflet Length (mm)
13.8
0.438
8.556
0.244
<0.0001
Stem thickness (mm)
1.03
0.015
1.056
0.022
0.44
Internode Length (mm)
15.6
0.916
13.06
0.701
0.0256
www.gri.msstate.edu
Northern
Eurasian
Frequency of number of leaflet pairs per leaf for northern watermilfoil
(SIB, left) and Eurasian watermilfoil (SPI, right).
Northern Watermilfoil
(Myriophyllum sibiricum)







Native submersed aquatic
plant
Leaves arranged in whorls
of 4 around stem, typically
remains rigid when
removed from water
Leaves have < 12 leaflet
pairs
Leaf tips are round not flat
Reproduces by stem
fragments and turions
Northern watermilfoil often
has longer leaves than
Eurasian watermilfoil
ID Characteristics: Round
leaf tips and < 12 leaflet
pairs
Eurasian Watermilfoil
(Myriophyllum spicatum)
 Introduced from Europe
 Submersed evergreen
perennial
 Spreads by root crowns,
runners, and fragments
 Grows in 2 to 15 feet of
water, forms surface canopy
 Leaves are in whorls of 4
around stem
 ID Characteristics: Flat leaf
ends, Flat apical meristem, >
12 leaflet pairs
Genetic Analysis Findings
• All three labs agree that plants
identified as northern watermilfoil
were northern watermilfoil
• All three labs agree that plants
identified as Eurasian watermilfoil
were Eurasian watermilfoil
• No evidence of hybridization in any
samples
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Eurasian watermilfoil
Gets More Complicated…
• Hybridization
with M. sibiricum
• May form a
terrestrial form
on moist soil and
mud flats
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Habitat
• Lakes, rivers, reservoirs, ponds,
freshwater and brackish estuaries
• Low to moderate organic content in
sediment
• Fine clay to sand, cobble, and rock
crevices in sediment
• Quiet to high energy zone, rooting
below wave wash zone
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What do plants need?
Light
Water
Carbon dioxide
Oxygen
Water
Nutrients:
Nitrogen
Phosphorus
A Tale of Two Plants
CO2, O2
Nutrients
Water
Removal of
Toxic Gases
Emergent, Floating
Submersed
Requirements for Growth
Light
Water attenuates amount of available light, controls depth
distribution and growth rate
Nutrients
For both types of plants, sediment is bulk of source for major
limiting nutrients (N, P) of rooted plants
Water
You’re kidding, right?
Carbon dioxide
Gases diffuse 1,000x more slowly in water, rate of availability limits
photosynthesis
Oxygen
Oxygen may be low for respiration, particularly in roots
Temperature/Heat
As with all plants, temperature range may limit growth
Toxic gases in sediment (methane, sulfate)
Floating, emergent plants have a “flow-through” system for gas
exchange
A safe place to root
Disturbance, water level fluctuation, herbivory may limit growth
Comparison
between Eurasian
watermilfoil and
Native Pondweed Photosynthesis
Submersed plant
photosynthesis is
controlled by light levels
Madsen and Boylen 1988
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Maximum depth
of colonization
versus light
transparency
Canfield et al.
1985
Maximum depth
of plant growth
is largely
controlled by
light availability
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Plant Nutrition
Source of Nutrients
Water column
Sediment
Growth-dilution
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Nutrient Sources: Sediment vs. Water
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Barko et al. 1991
Tissue
Concentrations
of N and P
As the plants grow,
nutrient uptake
does not keep up
with the increasing
volume or biomass
of the plant
resulting in “growth
dilution” of nutrient
content in the
plants. If growth
continues, nutrient
Madsen limitation will
1991
eventually occur.
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Phosphorus
and Algae
Dillon and Rigler 1974. Limnology
and Oceanography Vol. 19, No. 5,
767-773.
Increased phosphorus in water
leads to more algal growth
While some increased algal
growth will benefit fish
production, too much algae leads
to oxygen depletion, fish kills, and
odor problems
Nutrients will also increase
growth of free-floating plants
This is Your Lake
on Phosphorus:
Excessive
planktonic
and
filamentous
algae or
duckweed is
directly
related to
fertilizing
ponds
Bicarbonate
Uptake
Many submersed
plants can use
bicarbonate as
well as dissolved
carbon dioxide
for
photosynthesis.
Bicarbonate and
carbon dioxide
together are
known as
dissolved
inorganic carbon,
or DIC
Stevenson 1988.
Limnol. Oceanogr.
33:867-893.
Inorganic Carbon vs. Photosynthesis
Adams et al. 1978. Limnol. Oceanogr. 23:912-919.
EWM versus Trophic Status:
Relative Abundance
Smith and Barko 1990
Oligotrophic
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Eutrophic
Plant Abundance
Plant Response to the Environment
Approximate
Boundary
Environmental Gradient
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EWM Abundance vs. Total
Phosphorus
1
0
0
8
0
6
0
MilfoAbundace
4
0
2
0
0
0
2
0
4
0
6
0
8
0
1
0
0
1
2
0
1
4
0
1
6
0
1
8
0
2
0
0
T
o
t
a
l
P
h
o
s
p
h
o
r
u
s
(

g
L
)
1
EWM Abundance by Trophic Index
MilfoAbundace
1
0
0
8
0
6
0
4
0
2
0
0
0
5
1
0
1
5
2
0
2
5
3
0
3
5
4
0
4
5
5
0
5
5
6
0
6
5
7
0
7
5
8
0
T
r
o
p
h
i
c
I
n
d
e
x
EWM
Abundance
and
Alkalinity
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Salinity and Water Chemistry
• Up to 33%
seawater
• Softwater to
hardwater
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Nichols and
Buchan 1997.
JAPM
Ecological Impacts
• Reduces oxygen in water beneath
canopy
• Increases internal nutrient loading,
phosphorus
• Shades native plants
• Alters predator/prey balance
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Eurasian watermilfoil
vs. Native Plants
Why does Eurasian
watermilfoil suppress
native plants?
•Various mechanisms have
been proposed, including:
–Ability to use
bicarbonate as a
photosynthetic carbon
source
–Photosynthetic
adaptations
–High productivity
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Canopy Formation
Vmax vs Km
Madsen et al. 1991
Light Compensation Point vs Km
Madsen et al. 1991
Daily
Carbon
Balance,
Open
Water
Madsen et al. 1991
Daily
Carbon
Balance,
Milfoil
Canopy
Madsen et al. 1991
Invasive Plants and Fish
• Alter predator/prey
balance
• After time, produces
large numbers of
stunted, underfed fish
• Valued by fisherman,
not fisheries biologists
• Concern (though no
data) that predatory
fish hide in wait in
dense vegetation for
salmonids
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Largemouth Bass
Production
Relative Fish
Aquatic Plants and Predator/Prey Balance
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Sunfish
Percent Plant Cover
Is this reversible? Does
Management do any Good?
Since shading is the main
mechanism of competition,
it is an elastic change – and
reversible
With some management
techniques, native plants
already present respond
positively in year of
treatment
With less selective
techniques, sufficient plant
propagules exist for
revegetation
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Selective Management with
Herbicides
Untreated mesocosm
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Mesocosm treated with
Triclopyr
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Restoration from Benthic Barrier
Eichler et al. 1995.
JAPM 33:51-54.
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Native Plant
Restoration from
Suction Dredging
Eichler et al. 1993.
JAPM 31:144-148.
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Four Life History Types
•Annual
–Overwinters by seed
only
•Herbaceous perennial
–Overwinters by a
vegetative propagule
•Evergreen Perennial
–Overwinters by
green shoot
•Woody perennial
–Overwinters as a
woody stem
–Rare in aquatic sites
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Seed
Tuber –
vegetative
propagule
Root Crown –
evergreen
perennial
Propagation and Spread
• Reproduction by
seed
• Reproduction by
vegetative means
• Spread by natural
causes
• Spread by humans
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Propagation
• Seed
– Seed set and
success
• Vegetative
– Autofragment
– Root Crown
– Rhizomes
– Runners
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Seed Set
Eutrophic lakes
produce more flowers
and higher
percentage of seed
set than oligotrophic
lakes
Madsen and Boylen 1989
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Seed Germination and
Environment
Madsen et al. 1988
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In Situ Seed Germination
Madsen et al 1988
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Seed Germination and Burial
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Drying
Period and
Seed
Germination
Eurasian
watermilfoil seeds
tolerate long
periods of drying
Hartleb and Madsen 1997
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Propagation
by Seed
•Large number of seeds
are produced by
Eurasian watermilfoil
•Seeds are viable, and
germinate underwater
•Few, if any, seedlings
survive to maturity
underwater
•Seed propagation not
important in most lakes
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Vegetative
Spread
Fragments
Runner
Rhizome
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VT DEC
Vegetative Propagation: Runners
•Eurasian watermilfoil
overwinters as root
crowns – a tight mass of
growing stems
•Underground stems
may produce new root
crowns
•Erect stem can fall over
and form new root
crown
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Vegetative Propagation: Fragments
• Autofragments formed
by plant tend to
predominate
• Allofragments from
breakage may also be
viable
• Autofragment
production is greatest
late in summer
• Autofragments may
overwinter
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Northern Asexual Spread
Peak rhizome spread in August, peak autofragment
formation in September
Madsen et al. 1988
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•Southern
population
vegetative
spread follows a
different pattern
based on
environmental
parameters
•Colony
expanded at rate
of 3.8 cm / day
Madsen and Smith 1997
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Invasion Process
Introduction
Colony Formation
Establishment
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Spread of Melaleuca
Campbell, F.T.
1997. In: J.O.
Luken and J.W.
Thierot,
Assessment and
Management of
Plant Invasions.
Springer, New
York
Spread of Melaleuca
Campbell, F.T. 1997. In: J.O. Luken and J.W. Thierot, Assessment and Management of Plant Invasions.
Springer, New York
Spread of Invasive Plants over Time
Hobbs and Humphries 1995. Conserv. Biol. 9:761-770.
Cost of
Control vs
Time of
Intervention
Hobbs and Humphries 1995. Conserv. Biol. 9:761-770.
Phases
of Invasion vs
Manage
-ment
Priority
Hobbs and Humphries 1995. Conserv. Biol. 9:761-770.
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“Natural” Dispersal
• Water movement
– Wave action
– Currents
– Tides
• Animal carriers
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Boat Launches
• Boats are the #1
mode of Eurasian
watermilfoil spread
in North America
• Boat launches are
the most common
site for first
infestations in a new
lake
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Where to Check on Boats and Trailers
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MN DNR
Prevention
•Educational signs at
boat launches, marinas
•Volunteer “inspectors”
to teach on EWM danger
•Volunteer Plant Survey
to watch for EWM in lake
•Target boat launches!
•Boats can be cleaned
manually without any
special equipment
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Phenology and Growth
• Eurasian
watermilfoil is an
evergreen perennial
• Annual growth
cycle varies across
country
• Storage of
carbohydrates is key
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Temperature, Light and Growth
500
Warm, Clear Year
Cool, Cloudy Year
Biomass (g DW m-2)
400
300
200
100
0
Jan Feb Mar Apr May Jun
Jul
Aug Sep Oct Nov Dec
-2
Biomass (g DW m )
500
300
200
100
0
J
F
M
A
M
J
J
A
S
O
N
D
J
A
S
O
N
D
J
A
S
O
N
D
-2
Biomass (g DW m )
500
Warm Water North Temperate
400
300
200
100
0
J
F
M
A
M
J
450
-2
Biomass (g DW m )
•Eurasian
watermilfoil
phenology
varies
geographically,
interannually,
and
between
lakes
Cold Water North Temperate
400
400
350
300
250
200
Warm Water South Temperate
150
100
J
F
M
A
M
J
Carbohydrate Allocation
Owens and Madsen 1998
Seasonal Carbohydrate Allocation
Owens and Madsen 1998
Total Nonstructural
Carbohydrate Content
Carbohydrate Low Point
Low Point
Month of the Year
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Carbohydrate:
TNC storage by
season
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Low Points in Carbohydrate Storage of
Eurasian watermilfoil Madsen 1997
•Low carbohydrate
storage in summer
through fall in
southern
populations of
Eurasian
watermilfoil
•Northern
populations usually
have a distinct low
point in early to mid
summer
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Eurasian watermilfoil Carbohydrate Low
Points
5
Northern Sites
Southern Sites
Frequency of Studies
4
3
2
1
Madsen 1997
0
A
M
J
J
Month of Year
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A
S
O
Autofragment Formation
•Plant produces stem
segments through
abscission layer
formation
•Timing is typically in
fall, in both north and
south
Madsen et al. 1988
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Eurasian watermilfoil
Management Application
•Timing of management
to coincide with low
point
•Timing of management
to prevent autofragment
formation
•Drawdown exploits lack
of resistant propagule
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Conclusion
Management goal is maintenance of low
invasive plant population with diverse
native plant community at most
economical cost
Before management of invasive plant
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After management of invasive plant
Dr. John D. Madsen
Mississippi State
University
Geosystems Research
Institute
Box 9627
Mississippi State,
MS 39762-9627
Ph. 662-325-2428
Fax 662-325-7692
E-mail:
[email protected]
www.gri.msstate.edu