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Interactions of biological and hydrogeochemical processes
facilitate phosphorus dynamics in an processes facilitate
phosphorus dynamics in an
Everglades tree island
Tiffany Troxler1, Carlos Coronado-Molina2, Damon Rondeau3, Steve
Krupa2, Fred Sklar2, Paul Wetzel4
1Southeastern Environmental Research Center, Florida
International University, Miami, FL; 2South Florida Water
Management District, West Palm Beach, FL;
3Everglades National Park Homestead FL; 4Smith College
Northampton MAEverglades National Park, Homestead, FL; Smith
College, Northampton, MA
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The importance of higher plants and patch ecosystems in
landscape nutrient distribution
• Alter the distribution of nutrients in soils via
leachingBolivia
Alter the distribution of nutrients in soils via leaching,
dissolution and interception of atmospheric deposition
• Redistribute nutrients as a function of allocation patterns,
rooting depth and root distribution (Jobbagy and Jacksonrooting
depth and root distribution (Jobbagy and Jackson 2001, 2004).
• Evident when tree patches are associated with the localization
of nutrients (Barrett and Burke 2000, Wetzel et
Brazil
localization of nutrients (Barrett and Burke 2000, Wetzel et al
2005, 2009).
• Facilitation effect is thought to promote the resilience of
those patches and ecological landscape (Rietkirk et al p g p (2004,
van Nes and Scheffer 2005).
• Poses opportunities for effective decision-making where
environmental management may depend on the integrity of
Florida
g y p g ypatch ecosystem dynamics i.e. Everglades tree
islands
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Nutrient accumulation and peat formation hypothesis of
Everglades Tree Islands
T I l dTree Island Ecosystems of the World, Paul
Wetzel, ,Tree Islands of the Everglades,
2002Fred H SklarFred H. Sklar
and Arnold van der Valk
High Head Wet Head Near Tail Far Tail
Fixed tree islands in deep slough intercept P through mechanisms
that accumulate P in upstream plant communities and transport P to
p p pdownstream plant communities where P is efficiently recycled
and retained (van der Valk and Sklar, 2002 and Wetzel et al.
2005).
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Nutrient accumulation hypothesis has developed to incorporate
the role of transpiration by trees in phosphorus dynamicsp y p p
y
Wetzel et al (2005, 2009, in review)
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An important issue for Everglades restorationAn important issue
for Everglades restoration
•The SFWMD, the US ACE and the CERP have identified the need to
better d t d th l i l d bi l i l b fit f t i l d i thunderstand the
ecological and biological benefits of tree islands in the
Everglades - one of the most visible indicators of the health of
the Greater Everglades Landscape.
•Changes in regional hydrology that can affect the vegetation
and soils of tree islands may also have serious consequences for
other components of th t E l d t (i l f P t h d d dthe greater
Everglades ecosystem (i.e. release of P to marshes, degraded
habitat for bird nesting).
•To address these restoration priorities, we investigated how
biogeochemical pattern and processes operating at multiple temporal
and spatial scales may influence tree island growth and patch
maintenance focusing on the i t ti f bi l i l h i l d i l h d l i f
tinteraction of biological, geochemical, and regional hydrologic
factors.
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Spatial and temporal variability in hydrology and water quality
of tree island 3AS3 and water quality of tree island 3AS3
• Previous research associated high soil P concentrations of dry
head with high concentrations of ions, esp. Na and Cl
• We hypothesized that water movement, mediated by hydraulic
processes that were punctuated by increased tree island p p
yevapotranspiration (ET) in the dry season, influenced the
precipitation of P and lateral flux of nutrients to downstream
components of the tree island ecosystem
• Our objectives were to: 1) characterize spatial and temporal
variability in diurnal ET patterns1) characterize spatial and
temporal variability in diurnal ET patterns, 2) characterize
temporal local and regional hydraulic patterns, and3) characterize
spatial and temporal hydrochemical patterns in ions (Na, Cl,
Mg K etc ) and nutrients among four tree island plant
communities andMg, K, etc.) and nutrients among four tree island
plant communities and the adjacent deep water slough.
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Tree island 3AS3
•In a region considered to bl d l hresemble intact
ridge-slough
landscape features•Tear-drop shape with four p pdistinct plant
communities
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Tree Island 3AS3 Bulk Soil N and P Concentrations
3AS3 Soil TP and TN
50000
60000
30000
40000
mg
kg-1
)
TP
TN
10000
20000(m
0Head (0-
10) Head
(10-20) Head(20+)
Near Tail(0-10)
Near Tail(10-20)
Near Tail(20+)
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FIELD DESIGN
CONCEPTUAL DESIGN
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Spatial and Temporal Variability of Phosphorus in Soil Water of
3AS3 Wet Head
Spatial
Leads to large infiltration fluxes (SRP export) and net
ecosystem export of 1 29 ±
W C E
ecosystem export of 1.29 ±1.35 g P m-2 yr-1 from Wet Head
Spatio-temporal
30 cm
Whereas, ecosystem P budget of Near Tail is fairly balanced
(i.e. I=O; import: 0.05 ± 0.19 g
60 cm
( ; p gP m-2 yr-1)
60 cm
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Potential evapotranspiration, Water Level & Soil Elevationin
Tree Island 3AS3
0.25
11.5
12.0ET potential
Wet Head (ft.)
in Tree Island 3AS3
HH soil elevation
AUG 07 AUG 080 15
0.2
(in.)
10.5
11.0
el (f
t.)
( )
FEB 08 FEB 09
0.1
0.15
ET p
oten
tial (
9.5
10.0
et H
ead
Leve
0.05
E
8.5
9.0
9.5
We
0
4/1/07
/30/07
/28/07
/25/07
/23/07
/21/08
/20/08
/18/08
/16/08
/13/08
/11/08
1/9/09
3/9/09
5/7/09
8.0
8.5Lowest soil elevation (WH)
4/ 5/3 7/2 9/2 11/2 1/2 3/2 5/1 7/1 9/1 11/1 1/ 3/ 5/
Dark circles show sampling events
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I. Diurnal hydraulic patterns –low water dry down period low
precip high ET
Early dry season (April 21-27, 2008) hydraulic head levels at 15
min. intervals in central dry head (X12D) and wet head (N3D)
locations at 60cm depth.
low water, dry down period, low precip, high ET
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I. Diurnal hydraulic patterns –high water, rising water table,
high precip, high ET
Early wet season (September 11-17, 2008) hydraulic head levels
at 15min. intervals in central dry head and wet head locations at
60cm depth.
high water, rising water table, high precip, high ET
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I. Diurnal hydraulic patterns –moderate water table, dry down
with precipitation event low ET
Late wet season (December 8-13, 2008) hydraulic head levels at
15min. intervals in central dry head and wet head locations at 60cm
depth.
down with precipitation event, low ET
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The physiological influence of tree island plants & plant
communities on local and regional hydrology
Maximum daily transpiration rate coincides ith t t h d li h d d
d twith greatest hydraulic head drawdown at
0.6m depth but also evidence for influence at 2.8 and 8.4m
depths
Wetzel, Sklar, Coronado, Troxler, Krupa, Ewe et al. In review.
Critical Reviews in Environment and Technology.
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II. Local hydraulic patterns –potentiometric surface at 30cm
(shallow) depth
Hydraulic head levels (mm) in February 2008. Axes plot locations
are in UTM. Dashed line is tree island boundary showing High Head,
Wet Head and Near Tail.
AUGUST 2008- 30cm depth
553700February 2008 August 2008
553650
30703072307430763078
B.
553550
553600
30543056305830603062306430663068
553450
553500
30403042304430463048305030523054
553350
5534003038
731750 731800 731850 731900 731950 732000 732050
732100553300
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Total dissolved phosphorus (TDP) at 30cm depth. Axes plot
locations are in UTM.
III. Local Hydrochemical Patterns (shallow) – TDP
Dashed line is tree island boundary showing High Head, Wet Head
and Near Tail.
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WCA 3A MARCH 2007
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Total dissolved phosphorus (TDP) at 30cm depth Axes plot
locations are in UTM
III. Local Hydrochemical Patterns (shallow) – TDPTotal dissolved
phosphorus (TDP) at 30cm depth. Axes plot locations are in UTM.
Dashed line is tree island boundary showing High Head, Wet Head and
Near Tail.
Only sampling where waterOnly sampling where water was present
at 30cm in HH
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Sodium (Na) concentrations in August 2008. Axes plot locations
are in UTM.
III. Local Hydrochemical Patterns – Na. ( ) g p
Dashed line is tree island boundary showing High Head, Wet Head
and Near Tail.
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IV. Average Local and Regional Hydrochemical Patterns
DRY HEAD WET HEAD NEAR TAIL FAR TAILDepth(m)
Na(meqL
Sp Cond
TDP(μmol
Na(meqL
Sp Cond
TDP(μmol
Na(meqL
Sp Cond
TDP(μmol
Na(meqL
Sp Cond
TDP(uM)(m) (meqL
-1)Cond (uS/cm)
(μmolL-1)
(meqL-1)
Cond (uS/cm)
(μmolL-1)
(meqL-1)
Cond (uS/cm)
(μmolL-1)
(meqL-1)
Cond (uS/cm)
(uM)
0 0.74 359 0.16 0.72 353 0.21
0.2-0.3 20.9 3030 11.69 2.28 718 22.93 2.80 933 1.00 0.93 471
0.48
0.5-0.6 9.27 1611 9.58 2.53 1031 9.89 7.62 1525 0.86 1.06 779
0.70
2.45 2.66 874 0.23 1.59 1109 0.28
10.67 1.63 901 0.12 1.84 1276 0.22
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IV. Average Local and Regional Hydrochemical Patterns
DRY HEAD WET HEAD NEAR TAIL FAR TAILDepth(m)
Water Type/
pH TDP(μmol
Water Type/
pH TDP(μmol
Water Type/
pH TDP(μmol
Water Type/
pH TDP(μmol(m) yp
SIcalcite(μmolL-1)
ypSIcalcite
(μmolL-1)
ypSIcalcite
(μmolL-1)
ypSIcalcite
(μmolL-1)
0 Ca-HCO3/A
7.37 0.16 Ca-HCO3/U
7.13 0.21
0.2-0.3 Na-HCO3/S
6.90 11.69 Ca-HCO3/U
6.38 22.93 Ca-HCO3/A
6.50 1.00 Ca-HCO3/U
6.40 0.48
0.5-0.6 Na-HCO3/
6.97 9.58 Ca-HCO3/
6.68 9.89 Ca-HCO3/
6.70 0.86 Ca-HCO3/
6.53 0.703
S3
S3
S3
A
2.45 Ca-HCO3/S
6.98 0.23 Ca-HCO3/S
6.60 0.28
10 67 C 6 68 0 12 C 6 60 0 2210.67 Ca-HCO3/S
6.68 0.12 Ca-HCO3/S
6.60 0.22
S=supersaturated, A=approximately saturated, and
U=undersaturated with respect to calcite
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Model for biological and hydrochemical interactions in P
cycling
DRY HEAD
WET HEAD
NEAR TAIL
FAR TAILHEAD HEAD TAIL
12
Na
1) Evapotranspiration & mineral
precipitation/dissolution
2
3/4 44
2) TDP lateral transport3) TDP lateral transport, infiltration
& precipitation4) Plant uptake, peat deposition, leaching and
transport
Regional hydrology influences the rate of ET & concentration
level of phosphorus
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ConclusionsMi l i it ti t ib t t t i l d t bilit• Mineral
precipitation contributes to tree island stability –trees (esp. C.
icaco) influence this process via exclusion of Na & biogenic
mineral saturationg
• Precipitation/dissolution reactions likely contribute to TDP
lateral transport (but on short time scale) – do extreme dry
downs/pH gradients enhance P dissolutionextreme dry downs/pH
gradients enhance P dissolution & transport?
Future Directions• Continuous conductivity measurements to
capture
potential for dissolution• Carbonate rock dissolution
experiments to assess
potential for P release• Completed installation of similar
piezometer network in aCompleted installation of similar piezometer
network in a
“Ghost” tree island –little carbonate rock/soils present
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Acknowledgements FIU Wetland Ecosystems Ecology lab
South Florida Water Management DistrictU d d t d hi h h l h i t
tUndergraduate and high school research assistants