Grantee Research Project Results

2008 Progress Report: Experimentally Partitioning Effects of Hydrologic Regime on Vegetation and Soils to Develop Predictive Models for Restoration of Freshwater Wetlands

EPA Grant Number: EM832981
Title: Experimentally Partitioning Effects of Hydrologic Regime on Vegetation and Soils to Develop Predictive Models for Restoration of Freshwater Wetlands
Investigators: Scinto, Leonard , Richards, Jennifer
Institution: Florida International University
EPA Project Officer: Aja, Hayley
Project Period: January 1, 2007 through December 31, 2009
Project Period Covered by this Report: January 1, 2008 through December 31, 2009
Project Amount: $193,400
RFA: Targeted Research Grant (2006) Recipients Lists
Research Category: Hazardous Waste/Remediation , Targeted Research

Objective:

Hydrologic parameters are the most important, but least understood and quantified components of wetland ecosystems. Our purpose is to generate data to contribute to the development of a predictive model quantifying the relationships between hydrologic parameters and plant, soil and ecosystem components of freshwater wetlands. In addition, the processes which create and maintain marsh heterogeneity and ridge and slough topography including water depth, hydroperiod, water velocity and the timing of inundation will be quantified. Important hydrologic parameters include water depth, hydroperiod, water current velocity and timing of inundation. The focus of research for the first three years of this proposed study is to determine the effects of water flow and depth on marsh plant establishment and spatial distributions, and on soil accretion/sedimentation in relation to marsh plant species. Specifically, our objectives are (1) to determine what hydrologic conditions enhance ridge expansion into sloughs, and (2) to determine the effects of current velocity on plant productivity, organic decomposition, and soil/particulate deposition. The major objectives of the project are testing the effects of water depth and flow rates on marsh plant species colonization and growth. The overall goal is to provide data needed to properly restore or create wetlands lost or highly modified by anthropogenic activities. We are conducting our research in the Loxahatchee Impoundment Landscape Assessment Project (LILA) which consists of replicated wetland mesocosms that mimic many features of the Everglades marsh while having the capacity to manipulate water depth and flow. Replicated cells are being used to test and quantify effects of hydrologic treatments on plant and soil responses. The significant advantages that these cells provide include cell size, controlled hydrology, and the ability to test one variable at a time. Additionally, by incorporating this research at LILA are able to incorporate and benefit from other work being done at this site including; water velocity experiments, particulate transport experiments, and tree island species survival experiments, etc. Therefore, our expected results should produce some of the best guidelines for wetlands ridge and slough habitat creation and restoration methodologies needed by managers.

Progress Summary:

To date, we have initiated our experiment to determine the effects of water depth and flow rate on growth of common Everglades marsh species, as well as to understand how these species affect sedimentation, soil-building and nutrient dynamics. We have planted 72, 2x2 meter square plots in two mesocosms M1 and M2. We are operating M1 in a “no-flow” condition where water levels (stage and hydroperiod) are being manipulated by slow water inflow so as to minimize water velocity. In M2 we are seeking to maintain the same stage and hydroperiod but will be continually recirculating water thus trying to maintain “flowing” conditions. Flow and no-flow conditions have been qualitatively confirmed via dye studies as reported in our First Annual Report (Nov. 2007). The Dye study has shown that vegetation upstream of any plot is going to influence the water velocity. We will therefore monitor future velocity by placing Acoustic Doppler Velocity meters (ADVs) in various locations (4-5) for a period bracketing the RAST plot samplings. These should confirm velocities greater in M2 than in M1 when conducted in conjunction with gate openings and pump operations.

Three keystone Everglades wetland species: sawgrass (Cladium jamaicense), spikerush (Eleocharis cellulosa), and water lily (Nymphaea odorata) have been planted in the 2 x 2 m patches in several “habitats” including shallow (SS) and deep sloughs (DS), middle of ridges (MR), and ridge edges (ER) (Fig. 1). We collected and transplanted each species from other portions of LILA to our plots in June 2007. Within 1-2 months it became apparent that our transplanted Cladium did not take in the RAST plots. We therefore had sawgrass grown from seed by a commercial supplier (Aquatic Plants of Florida, Sarasota FL). The plants were started in September 2007 and were planted at RAST plots mid-February to mid-March 2008 (Fig. 2). We therefore re-scheduled our start date for initial biomass sampling to May 15^th giving the Cladium plots at least 2 months to become established. Vegetation was removed from 0.5 m perimeter of all plots in late April and early May to reestablish a t0 condition for plot expansion/colonization. Additionally the natural colonization plots were established just prior to the May 15th start date. Clearing was done by hand-harvesting or by spraying with glycophosate herbicides. Care was taken to insure transplants within plots were not affected.

Figure 1. Diagrammatic representation of LILA mesocosms 1 and 2 showing RAST plots where C = Cladium jamaicense, N = Nymphea odorata, and E = eleocharis cellulose. Natural propagation plots are at the heads of the mesocosms (red squares).

Figure 2. Commercially grown Cladium jamaicense. These plants were planted in RAST during mid-February to mid-March 2008 approximately 1 month after this photo was taken.

Nymphaea and Eleocharis were routinely monitored for presence/absence during the wet season (approximately June through December 2007). When absent additional transplants were replanted. Presence/absence (mortality) surveys were implemented in April 2008 in anticipation of biomass data collection. However, no new replanting will be conducted as we are now recording for mortality. Due to the experimental treatments that we have deployed, we expect that during the dry season, when water levels are below the soil surface in ridge habitats, Nymphaea would lose leaves and appear as absent. However, as water levels rise, Nymphaea will replace its lost leaves. Prolonged absence records, during alternating wet/dry cycles will confirm mortality.

Plant measurements have been resolved and are as follows: 1) N. odorata – presence/absence, density (number of leaves per plant), and leaf size (width of the most recently matured leaf), 2) E. cellulosa – presence/absence, density (number of stems per subplot), and stem height (length of the longest stem), and 3) C. jamaicense – presence/absence, density (number of culms), and leaf length (length of the longest leaf). All measurements are conducted per 0.5 m² subplot, with 6 randomly selected subplots per 2 m² plot. Random subplots were selected so that four subplots were located along the plot edge and 2 subplots were located in the plot interior. Additionally, sediment accretion pins (stakes) will be installed in early June 2008. To facilitate measurements without disturbing our plots, especially the soil layers, we have developed a movable gangplank that will be laid across a plot and supported by a block in the plot center to allow subplot access without sediment disturbance (Fig. 3).

Figure 3. Arrangement of plot showing subplots. All 16 subplots are monitored for presence/absence while the 6 hashed subplots are monitored for biomass on a quarterly basis. Also shown are locations for sediment accretion pins.

We present a revised 2008-2009 sampling and experimental set-up schedule to reflect these necessary changes (Table 1). We have also modified our sampling schedule to reflect plant measurements that will be collected every three months from the t0 start date (May 15^th 2008), and natural colonization plots that will be established and monitored over 6 month intervals.

Table 1. Revised Project Schedule – tentative
YEAR	TARGET DATE	TASKS & REPORTING DEADLINES
2007	25 –Oct	SURVEY PLOTS AND REPLANT (except Clad.)
	30- Nov	FIRST ANNUAL REPORT
2008	25 – Jan	SURVEY PLOTS AND REPLANT (except Clad.)
	15-Feb to 15 Mar	Replant Cladium in all plots
2008	7-May	NATURAL COLONIZATION PLOT SET-UP (REMOVE VEG)
	7-May	PLOT EXPANSION VEGETATION REMOVAL
	15-May	DATA COLLECTION START DATE – PLANT MEASUREMENTS
	30-May	SEMI-ANNUAL REPORT
	7-Aug to 7- Sept	ADV local velocity measures
	7-Aug	Deploy sedimentation Traps
	15-Aug to 30-Aug	PLANT MEASUREMENTS
	7-Nov to 7-Dec	ADV local velocity measures
	15-Nov to 30-Nov	PLANT MEASUREMENTS
	15-Nov	Measure and Reinitiate Natural Colonization Plots
	30-Nov	SECOND ANNUAL REPORT
2009	7-Feb to 7-Mar	ADV local velocity measures
	15-Feb to 28-Feb	PLANT MEASUREMENTS
	7-May to 7-Jun	ADV local velocity measures
	15-May to 30-May	PLANT MEASUREMENTS
	15-May	Measure plot expansion
	15-May	Measure and Reinitiate Natural Colonization Plots
	30-May	SEMI-ANNUAL REPORT
	7-Aug to 7-Sept	ADV local velocity measures
	7-Aug	Deploy sedimentation Traps
	15-Aug to 30-Aug	PLANT MEASUREMENTS
	30-Nov	THIRD ANNUAL REPORT/FINAL
	30-Dec	PROJECT END DATE

B. Significant issues associated with conducting the research as proposed

At this point the most significant modification of our work plan was in the re-scheduling of the initiation of biomass monitoring and experimental start date to May 15, 2008. Our current 2 mesocosm design incorporates three replicate plots of each of three species in 4 wetland habitats in a no-flow and a flowing treatment. Velocity will be a relative measure, with expected flows to be greater in M2 than M1. This experimental design should allow our objectives to be tested thereby eliminating the necessity of planting two additional mesocosms (M3 and M4). It is expected (from LILA Velocity measures) that the velocity in M3 and M4 will not match that of M1 and M2. Therefore these additional cells will not provide true replication. We therefore decided to reduce the number of mesocosms to 2, thus utilizing only M1 and M2.

Supplemental Keywords:

ecology, decision making,, RFA, Ecosystem Protection/Environmental Exposure & Risk, Scientific Discipline, ECOSYSTEMS, Aquatic Ecosystem, Aquatic Ecosystems & Estuarine Research, Terrestrial Ecosystems, Hydrology, aquatic ecosystem restoration, bidoveristy, modeling ecosystem change, wetland stabilization, ecosystem monitoring, fate and transport, wetlands, hydrologic modeling, hydrodynamics

Relevant Websites:

http://www.sfwmd.gov

Progress and Final Reports:

Original Abstract

2007 Progress Report

Final