Phosphorous Storage in Isolated Wetlands. M. Clark, E. Dunne, K. McKee, N. Balcer, J. Smith, K.R. Reddy and S. Grunwald

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1 Phosphorous Storage in Isolated Wetlands M. Clark, E. Dunne, K. McKee, N. Balcer, J. Smith, K.R. Reddy and S. Grunwald

in isolated wetlands Hydroperiod and soil phosphorus

2 Outline Landscape scale spatial phosphorus distribution Processes effecting phosphorus storage in isolated wetlands Hydroperiod and soil phosphorus storage Potential effect of hydrologic restoration Information gaps

3 Wetlands within the Priority Basins Area (ha) % of Basin Wetland Area 21,649 18% Hydrologic Connectivity Riparian 8,926 41% Nonripairian 12,723 59% Community Type Emergent Marsh 15,748 73% Forested 3,259 15% Shrub Scrub 1,551 7% Other 1,091 5%

4 Sampling Locations Dairy Forested/Scrub 6 Emergent Marsh 15 Improved pastures Forested/Scrub 4 Emergent Marsh 81 Unimproved pastures/ rangeland Forested/Scrub 1 Emergent Marsh 11 Total 118

5 Sampling Protocol U E C U C C center E E U edge C E upland U

6 Wetland Soil Phosphorus by Landuse Soil TP, g/m a b b Dairy Improved Pasture Unimproved Pasture Landuse Landuse Dairy sites had significantly greater soil phosphorus levels than improved or unimproved pasture landuse types.

7 Soil Phosphorus by Sampling Zone TP g/m a b b Center Edge Upland Sampling zone Center wetland zones had significantly higher phosphorus than edge or upland zones.

8 Total Phosphorus Storage in Sampled Wetlands Mean TP Mean wetland size P per wetland P stored in all sampled wetlands g/m 2 ha kg kg Dairy (n = 21) Improved Pasture (n = 84) Unimproved Pasture (n = 12) a a , a a , b a ,566

adjacent upland pasture (130kg ha -1 ) Up-scaling of 118 sites using remote spectral imaging, wetland classification

9 Spatial Summary Roughly half of the 12,000 ha of historically isolated wetlands are drained, most of these are on improved pasture Isolated wetland surface soils (0-10cm) contained almost twice as much phosphorus (250kg ha -1) than adjacent upland pasture (130kg ha -1 ) Up-scaling of 118 sites using remote spectral imaging, wetland classification and regression tree analysis estimate 2, metric tons of P is stored in the top 0-10 cm of isolated wetlands in the basin.

10 Site Specific Studies Beaty Larson Dixie

11 Phosphorus Storage Pools Plant, Litter and Soil Total Phosphorus 16,000 14,000 88% Beaty Larson TP (mg/m2) 12,000 10,000 8,000 6,000 12% of P is immobilized in vegetation 4,000 2, % 1% 3% BGB Litter Soil AGB Component

12 Plant Tissue Phosphorus Leaching Cum ulative P flux (m g P/g tissue) Time (days) Panicum Bahia Polygonum Juncus Control

13 Plant Tissue Phosphorus Leaching 17 day Total Cumulative P Flux in Site Water Species Aerobic (mgp/g tissue) % tissue P released Anaerobic (mgp/g tissue) % tissue P released Panicum hemitomon a a 3.6 Paspalum notatum b b 49.9 Polygonum hydropiperoides c c 71.2 Juncus effusus b Species leaching response was best explained by tissue P concentration b 57.3

1 + 10.8 b 38.8 + 4.1 a Upland 11.12 + 0.7 c 48.8 + 5.4 a 49.7 + 6.

14 Distribution of Organic Matter, Iron and Aluminum in Wetlands Organic Matter % Oxalate extractable Iron (g/m 2 ) Oxalate extractable Aluminum (g/m 2 ) Center a a a Edge b b a Upland c a a Significantly greater organic matter content in core and edge sampling zones. Iron and aluminum were more prevalent in the upland and edge sampling zones.

15 P Relationship with Organic Matter Adjacent uplands Wetland Edges Wetland Centers

Phosphorus leached from plant tissue is species specific and related to tissue phosphorus concentration.

16 Process Storage Summary Soils are the dominant storage pool of phosphorus. Phosphorus stored in plant tissue can have significant leaching losses upon senescence. Phosphorus leached from plant tissue is species specific and related to tissue phosphorus concentration. Soil P is predominantly associated with organic matter in wetland centers (87%) and edges (84%), but with other compounds in upland soils (only 31% associated with organic matter)

17 Hydroperiod and Storage Potential Hydroperiod vs. Vegetative Zones Organic Matter vs. Vegetative Zones Organic Matter Content % Center Edge Upland zones

18 Total Phosphorus and Organic Matter R 2 = Wetland Beaty North Beaty South Larson East Larson West Phosphorus, mg kg -1 TP Organic Matter Content, % loi

19 Hydroperiod vs. Soil Phosphorus (Larson East) R 2 = Phosphorus mg kg -1 Hydroperiod

20 Hydroperiod vs. Soil Phosphorus (All Sites) 0.71mg P kg -1 day -1 R 2 = Phosphorus mg kg -1 Hydroperiod

21 Conceptual Effect of Hydrologic Restoration upland edge center edge upland upland edge center edge upland

22 Change in Phosphorous Storage Capacity Zone Transitions Dairy Improved Pasture Unimproved Pasture ( g P m -2 ) ( g P m -2 ) ( g P m -2 ) Edges become Centers Uplands become Edges Uplands become Centers Matched pair analysis by site

23 Potential Increase in Soil Storage Capacity due to Hydrologic Restoration of Isolated Wetlands in the Basins Total area Ditched Upland becomes Edge Edge becomes Center Increased Phosphorus Storage Capacity (kg) (ha) (%) (g TP m -2 )---- 5% (293 ha) 10% (588 ha) 20% (1176 ha) Dairy % ,556 3,110 6,221 Improved 6,337 72% ,661 31,322 62,645 Unimproved 2,127 45% ,173 6,346 12,692 Total 20,390 40,779 82,558

Depending on the degree of hydroperiod increase, a significant increase in soil phosphorus concentration exist.

24 Storage Summary Phosphorus storage in isolated wetlands is significantly related to organic matter content. Organic matter content is in part related to wetland hydroperiod. Depending on the degree of hydroperiod increase, a significant increase in soil phosphorus concentration exist. Findings suggest an increased soil phosphorus concentration of 0.71mg P kg -1 per day of increased hydroperiod. These findings do not include any new accretion of soils in response to hydroperiod.

We do not know the role other factors such as cattle grazing, plant species or nitrogen availability influence

25 Information Gaps We do not have an estimate of how long it would take for soil characteristics to shift. We do not know how changes in hydroperiod will effect the rate of new soil accretion. We do not know the role other factors such as cattle grazing, plant species or nitrogen availability influence organic matter accretion in wetlands. How can soil amendments be used to increase phosphorus storage potential in the absence of increased organic matter accretion?

PHOSPHORUS MANAGEMENT IN THE OKEECHOBEE BASIN: Legacy Phosphorus Implications to Restoration and Management

PHOSPHORUS MANAGEMENT IN THE OKEECHOBEE BASIN: Legacy Phosphorus Implications to Restoration and Management June 2, 2010 K. R. Reddy, M. Clark, J. Mitchell, E. Dunne A. Cheesman, and Y. Wang University