Upload
others
View
3
Download
0
Embed Size (px)
Citation preview
A landscape-scale approach to
management of a major invasive species,
Phragmites australis, in Chesapeake
Bay tidal wetlands
Dennis Whigham1, Eric Hazelton1,2, Melissa McCormick1, and Karin Kettenring1,2
1Smithsonian Environmental Research Center
2Utah State University
Saltonstall. 2002. PNAS 99: 2445-2449
Rhode River 1970
Rhode River 2009
A fundamental question in ecology
What drives the (rapid) spread of invasive species?
Characteristics of environment
Characteristics of invader
0 25 50 75 10012.5Kilometers
.
LANDUSEAgricultural
Developed
Forested
Mixed-Ag
Mixed-DevElizabeth
Chesapeake Bay
Warwick
Piankatank
Totuskey
St. Clements
St. Mary'sBreton
Wicomico
Tred Avon
Wye
Southeast
Langford
BirdBack
Patapsco
Curtis
Severn
Rhode
Battle
Miles
Corsica
Gwynns Falls
Jones Falls
Magothy
South
Manokin
MillSt. Leonards
Nomini
Ware
Pagan
Subestuaries of Chesapeake Bay studied as part of EPA-funded Atlantic Slope Consortium project
King, R.S., W.V. Deluca, D.F. Whigham, and P.P. Marra. 2007. Threshold effects of coastal urbanization on Phragmites australis (Common Reed) abundance and foliar nitrogen in Chesapeake Bay. Estuaries and Coasts 30: 469-481.
Have environmental factors driven the spread of Phragmites in recent years?
Phragmites seedling emergence higher in disturbances (p<0.001) in some plant communities (p<0.001). Rhizome emergence was low and not related to disturbances
% s
eedl
ing
emer
genc
e(m
ean
± 1
SE
)
0
10
20
30
40 controlaboveground disturbancebelowground disturbance
Iva Schoenoplectus Spartina/Distichlis Typha
a
b
ab
a
b b
a
b
b
a a
a
Phragmites seedlings (but not rhizomes) growth higher under elevated nitrogen (p=0.003) and plants were taller and produced more stems
Tota
l bio
mas
s (m
ean
± 1
SE
)
0.0
0.5
1.0
1.5
2.0
2.5
0 g m-2 yr-19 g m-2 yr-118 g m-2 yr-135 g m-2 yr-170 g m-2 yr-1
a
ab
c bc
bc
More florets (p=0.006) and inflorescences (p<0.001) are produced per plant with elevated nutrients
Num
ber o
f flo
rets
(mea
n ±
1 S
E)
0
1000
2000
3000
4000 ambient nutrientselevated nutrients
Num
ber o
f inf
lore
scen
ces
(mea
n ±
1 S
E)
0
2
4
6
8
10
12
14ambient nutrientselevated nutrients
Kettenring, McCormick, Baron, and Whigham, J. Appl. Ecol. 2011
CO2 + N experiment at the SERC Global Change Research Wetland
Mozdzer TJ, Megonigal JP (2012) Jack-and-Master trait responses to elevated CO2 and N: A comparison of native and Introduced Phragmites australis. PLoS ONE 7(10): e42794. doi:10.1371
Have biological factors driven the spread of Phragmites in recent years?
How does Phragmites reproduce and spread?
Rhizomes - Clonal (asexual) propagation
Seeds - Sexual reproduction (outcrossing)
Shoots - Clonal (Rooting at nodes)
Substantial genetic variation within and among patches: 91% of patches had >1 genotype
McCormick, Kettenring, Baron, and Whigham. 2010. Wetlands
# of genotypes per patch increased with watershed development
Kettenring, McCormick, Baron, and Whigham, J. Applied Ecology
Watershed Class
Forested Mixed- Developed
Developed
# of
gen
otyp
es p
er p
atch
(o
f 4 p
ossi
ble;
mea
n +
1SE
)
0
1
2
3
4 p=0.035 r2=0.145
McCormick, Kettenring, Baron, and Whigham J. Ecology 2011
Bruvo genetic diversity (natural log transformed)
-6 -5 -4 -3 -2
Prop
ortio
n vi
able
see
ds (l
ogit
of m
ean)
-8
-6
-4
-2
0
2R2=0.26, P=0.0003
Kettenring, McCormick, Baron, and Whigham J. Applied Ecology . 2011
Seeds and leaves collected
Increased local genetic diversity positively related to viable seed production
McCormick, Kettenring, Baron, and Whigham Wetlands 2010, J. Ecology 2011
The majority of dispersal is local and within subestuaries
Where do the seeds establishing patches on hardened shoreline come from?
Mean distance separating sample pairs (m)
Rhode River
0 1000 2000 3000 4000 5000
Sim
ilarit
y (m
ean
Mor
an's
I +S
E)
0.0
0.2
0.4
0.6
0.8
1.0 Chesapeake Bay – 9 subestuaries
0 500 1000 50,000
100m 500m
Conceptual Model Based on Recent Findings
Feedback
Shoreline Structures • Genetic diversity • Dispersal
Phragmites Removal Experiment • Water quality • Fish and invertebrates transects • Transects • Each quadrat (n = 405):
– Plant Community – Nutrients – Salinity – Phragmites vigor – Phragmites clonal diversity – Phragmites flowering density – Phragmites herbivore density – Seed bank
Current Project (Focus: three types of subestuaries)
Shoreline disturbances
Shoreline TypeNatural Riprap Bulkhead
Gen
otyp
es(m
ean
+se)
0
1
2
3
4
5
6Forested Agriculture Developed
Shoreline hardening promotes more genetically diverse Phragmites patches
shoreline P=0.005 watershed P<0.001 shore x w-shed P=0.335
*
Why are patches associated with hardened shorelines more diverse? •Wave action deferred by bulkheads may cause repeated disturbances or may concentrate dispersing seeds at the edges. •Riprap may provide places for seeds to lodge. •Areas targeted for hardening may be those with the greatest fetch and/or disturbance and so might have the most (and most diverse) Phragmites anyway.
Herbicide application (glyphosate) over three years
At each site • Native • Phragmites removed • Phragmites control
Patapsco River (Developed)
Native outlier likely Iva
Native Control
Removal
St. Leonard River (Forested)
Outlier is open water
Native Control
Removal
Wye River (Agricultural)
Native Control
Removal
Is there any hope that effective management can happen?
Hazelton, E.L.G., Mozdzer, T.J., Burdick, D. Kettenring, K.M. and Whigham, D.F. 2014. Phragmites australis management in the United States: 40 years of methods and outcomes. AoB Plants, doi:10.1093/aobpla/plu001
Implications For Management • Without an effective management strategy, the non-native genotype potentially could occupy all brackish wetlands and, potentially, the majority of tidal freshwater wetlands •Effective long-term management can only be done at the scale of entire subestuaries (removal of primary sources of seeds)
•Following removal, management can focus on periodic inspections and removal of any new invasions.
•Efforts should be made to identify important subestuaries where most of the uplands are forested and few or relatively few patches of the non- native genotype occur. Complete removal and periodic inspections and follow-up are required.
•Some areas (e.g., around Baltimore and Norfolk) are so heavily invaded that removal and management are too expensive.
Rock Hall
Patapsco
Patch History
1970 – 1 patch Mid-1990s – 1 shoreline patch (VIMS) 2013 – 12 patches
St. Leonard Creek
Parkers Creek
Battle Creek
Fairhaven: Community action
Jay O’Neill – Head Technician, Plant Ecology lab, SERC Matt Sievers – SERC intern Heather Baron – SERC intern. MS - Oregon State Jared Staap – SERC intern. MS University of Maine Liza McFarland – SERC intern. MS – U. Maryland Hope Brooks – SERC intern. Senior at Penn State Funding sources: EPA – STAR program NOAA – Chesapeake Bay office Smithsonian Institution NOAA Smithsonian Institution
Matt
Heather
Melissa
Jared
Karin and Jay
Liza
Hope