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

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

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).

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)

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.

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.

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

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+)

FIELD DESIGN

CONCEPTUAL DESIGN

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

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

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

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

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

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.

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

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.

WCA 3A MARCH 2007

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

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.

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

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

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

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

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