Transcript PIE ASM PowerPoint 2004

FACTORS AFFECTING OLIGOHALINE
MARSH MACROPHYTE ZONATION
AND PRODUCTION AT THE PLUM
ISLAND ECOSYSTEM LTER SITE
Robert J. Daoust and James T. Morris
Department of Biological Sciences
University of South Carolina
Columbia, SC 29208
Plant communities
within estuaries
contain striking
examples of
zonation
Occurs along
multiple gradients
upstream
downstream
creekbank
upland edge
Upstream
Freshwater
Brackish
Zone
Saltwater
Downstream
Low Marsh - Spartina alterniflora
Mixed zone
Upland edge
High Marsh - Spartina patens
Creekbank
Plant community structure within
estuaries is inherently complex
Strong gradients of salinity stress
downstream -> upstream
creekbank -> upland edge
Upstream
Freshwater
marsh
Decreasing salinity
stress
Oligohaline
zone
Marine influence
Freshwater influence
Salt
marsh
Downstream
Low Marsh - Spartina alterniflora
flooded with each incoming tide
Mixed zone
High Marsh - Spartina patens
flooded only during extremely high tides
Decreasing
salinity
stress on
plants
These gradients of salinity
stress exist in conjunction
with ecosystem wide
nutrient limitation of
macrophyte production
Competitively inferior species relegated to the more
stressful environment
Low Marsh - Spartina alterniflora
Mixed zone
lower boundary
determined by
ability to withstand
salinity stress
High Marsh - Spartina patens
upward expansion
limited by ability
to compete for N
Along the downstream-upstream gradient nutrient limitation of
macrophyte production switches
Upstream
Freshwater
marsh
P-limitation
Oligohaline
zone
Salt
marsh
N-limitation
Downstream
Oligohaline marshes also exhibit
strong patterns of zonation
Lie at the critical interface
between P-limited freshwater
communities and N-limited
saltmarsh communities
What factors control marsh
macrophyte zonation within
the estuarine oligohaline
zone?
Plum Island Ecosystem
LTER, Rowley MA
Massachusetts
Boston
Woods Hole
Oligohaline
zone
Salt
marsh
Typha angustifolia
Upland edge
Spartina patens
Creekbank
Porewater salinity and sulphide concentrations
Sulphide
*
S-2
Salinity
Concentraion (uM)
400
300
Signficant
differences between
communities
10
+
8
6
*
+
200
4
Concentration (ppt)
500
[S-2]patens> [S-2]typha
p=0.0323
F=4.73, F1,95=3.95
Salinity
100
2
Signficant
differences between
communities
0
0
[Sal]patens> [Sal]typha
S. patens
T. angustifolia
p<0.0001
F=18.67, F1,95=3.95
The area dominated by T. angustifola is less physically stressful
NH4 and SRP concentrations
250
NH4
10
*
Concentraion (uM)
200
SRP
150
8
6
*
100
4
50
2
0
0
S. patens
T. angustifolia
Concentration (uM)
NH4+
Signficant
differences between
communities
[NH4]patens> [NH4]typha
p=0.0240
F=5.87, F1,22=4.30
SRP
No signficant
differences between
communities
CONTROLS ON MACROPHYTE ZONATION
Utilized a common reciprocal transplant experiment nested
with an N+P factorial fertilization experiment within an
oligohaline marsh along the Parker River
“Mixed Effects Complete Nested Block Design”
Four Blocks
Species
50 m x 5 m
Control
Phosphorus only
(10 M yr-1)
Nitrogen only
(30 M yr-1)
N+P
(10 M P yr-1 + 30 M N yr-1)
Typha angustifolia
}
Spartina patens
Untransplanted Transplanted
(replicated x 2)
Disturbed
Control
Massachusetts
Boston
Woods Hole
Tyhpa
angustifolia
Spartina patens
Typha angustifolia
1 m2 transplant plots
Spartina patens
Untransplanted response for both species
Net Annual Primary Production
Nutrient effect
p=0.01892
Species effect
p=0.0002
Net Annual Primary Production (g m-2 yr-1)
1800
1600
Species respond differently
to fertilization.
1400
1200
S. patens responds to N
and N+P suggesting
nitrogen limitation
1000
800
600
T. angustifolia responds
to P and N+P
suggesting phosphorus
limitation
400
200
0
SPC
TYC
SPP
TYP
SPN
SP=Spartina patens
TY=Typha angustifolia
TYN
SPF
TYF
Year effect
p=0.4074
Transplanted response for both species
Net Annual Primary Production
Species effect
p<0.0001
Nutrient effect
p<0.0001
Net Annual Primary Production (g m-2 yr-1)
1800
1600
T. angustifolia production
increases dramatically when
phosphorus availability is
increased, irregardless of N
availability
1400
1200
1000
800
Transplanted S. patens
production increases only
in the absence of P
enrichment
600
400
200
0
SPC
TYC
SPP
TYP
SPN
SP=Spartina patens
TY=Typha angustifolia
TYN
SPF
TYF
S. patens production
suffers when either P or
N+P is added to the system
Year response
p<0.0001
Response of Typha angustifolia
Nutrient treatment
p=0.0071
F=37.37
F=P>N=C
F3,4=6.59
Transplant effect
p=0.7855
Net Annual Primary Production
Net Annual Primary Production (g m -2 yr-1)
1800
1600
1400
1200
1000
800
600
400
200
0
CC
TC
C=untransplanted plot
T=transplanted plot
CP
TP
CN
TN
CF
TF
T. angustifolia
responds to P and
N+P fertilization the
same regardless of
whether it has been
transplanted into its
neighbouring
community
Year effect
p=0.0004
Response of Spartina patens
After the
first
of
S. patens
does
notyear
respond
fertilization
both N and
the same toitfertilization
N+Pwhen
stimulated
production
transplanted.
evenNutrient
when transplanted
treatment
Net Annual Primary Production
p=0.1038
Net Annual Primary Production (g m -2 yr-1)
1200
1200
Transplant effect
p=0.0341
1000
1000
Production
is stimulated
Production
is only
within its in
own
whenof
stimulated
thezone
absence
fertilized
with Nwhen
or with
P additions
both N+P
transplanted
When P availability is
increased S. patens is
supressed as it is out competed
by T. angustifolia
800
800
600
600
400
400
200
200
(for light and space)
00
CC
CC
TC
TC
C=untransplanted plot
T=transplanted plot
CP
CP
TP
TP
CN
CN
TN
TN
CF
CF
TF
TF
Year effect
P=0.2576
Summary
In the oligohaline zone, macrophytes are nutrient limited
Spartina patens and Typha angustifolia respond differently to
fertilization. S. patens --> Nitrogen
T. angustifolia --> Phosphorus
Both species are able to exist within its neighbouring zone
However, Typha angustifolia when fertilized with phosphorus
or N+P in combination performs better within its
neighbouring zone than does Spartina patens
When oligohaline marsh communities are fertilized with
phosphorus Typha angustifolia production increases
significantly and it becomes better able to survive under more
stressful physical conditions.
Competitively
inferior species relegated
the more
Thetocompetitive
When
N is added:
stressful environment
advantage of S. patens
is reduced allowing S.
alterniflora to move
upwards into the high
Low Marsh - Spartina alterniflora
marsh
Mixed zone
Zone dominated
by S. patens
shrinks
High Marsh - Spartina patens
Oligohaline marshes do not follow similar patterns
Inferior stress tolerator is relegated
to the more
The boundary
is
benign physical environment
determined solely by
Typha angustifolia
the ability of T.
angustifola to tolerate
physical stress
S. patens becomes more productive and is
+P
Expands downward
+N more likely to survive if it becomes
established
T. angustifolia
becomes
Not likely
to expand towards the upland
more adept at surviving
edge of the marsh
under more stressful
Spartina patens
conditions
In the past, emphasis has been placed
on nitrogen when considering the
impacts of cultural eutrophication on
coastal wetlands. These data suggest
that the importance of phosphorus
should not be overlooked as it may
also lead to shifts in the ecological
structure of these ecosystems.
YUMM!!!
AHHH!!! NO!!!!
Response of Spartina patens to fertilization
2000
1600
-2
Aboveground Biomass (g m )
1800
C
N+P
N
P
1400
1200
1000
800
F=N>P=C
600
p<0.001
400
200
Ja
n
M
a
M r
ay
Ju
l
Se
p
N
ov
Ja
n
M
ar
M
ay
Ju
l
Se
p
N
ov
Ja
n
M
ar
M
ay
Ju
l
Se
p
N
ov
Ja
n
M
ar
M
ay
Ju
l
Se
p
N
ov
Ja
n
0
2000
2001
2002
2003
Ja
n
M
a
M r
ay
Ju
l
Se
p
N
ov
Ja
n
M
a
M r
ay
Ju
l
Se
p
N
ov
Ja
n
M
a
M r
ay
Ju
l
Se
p
N
ov
Ja
n
M
a
M r
ay
Ju
l
Se
p
N
ov
Ja
n
-2
Aboveground Biomass (g m )
Response of Typha angustifolia to fertilization
2500
2000
C
N
P
N+P
2000
2001
2002
2003
F=P>N>C
1500
1000
500
0
p<0.001