Developing a tool to classify and map factors limiting plant growth in coastal marshes J. Andy Nyman, Vanessa D. Tobias School of Renewable Natural Resources, Louisiana State University Agricultural Center John D. Foret, Joy J. Merino National Marine Fisheries Service Ron D. DeLaune Department of Oceanography and Coastal Sciences, Louisiana State University Dayna Huval Department of Biology at the University of Louisaina at Lafayette image: 19 April 2008, NASA Stennis Space Center Aeronet Network

Nyman et al Estuarine Coastal and Shelf Science. 69: DeLaune et al Catena 17:

Maybe the limiting factor is salinity stress.

Maybe the limiting factor is nutrient availability.

Mapping the Factors Limiting Growth of Existing Emergent Wetland Vegetation in Coastal Louisiana: flooding stress, salinity stress, nutrient limitation understand why existing restoration projects are having the effects that they do adaptively manage existing restoration projects that have water control structures such as diversions, marsh management, etc. more accurately predict the effects of restoration alternatives

The ability to map limiting factors in agricultural crops has been routine for decades. The ability to map limiting factors in coastal wetlands is new: –Spartina patens. Most common plant in coastal Louisiana Mapping the Factors Limiting Growth of Existing Emergent Wetland Vegetation in Coastal Louisiana: flooding stress, salinity stress, nutrient limitation

A Tool for Identifying Limiting Factors collect 5 grams (about half a sandwich- sized ziplock bag) of “newest fully developed leaves if in plastic, then store on ice if in paper, then no ice needed oven-dry the leaves grind the dried leaves arrange for leaves to be analyzed for “Plant Environmental plus C and N” by the Soil Testing and Plant Analyses Laboratory (STPAL) at the LSU AgCenterSTPAL mail samples and $16/sample to STPAL use results to classify sample as flood- limited, salinity-limited, nitrogen-limited, or co-limited

using chemical content of S. patens leaves to classify limiting factors 1.Is the Mn content less than 223 ppm? a)if yes, then classify the site as flood stressed b)if no, then proceed to step 2

technical documentation Merino, J., D. Huval, and J. Nyman. in press. Implication of nutrient and salinity interaction on the productivity of Spartina patens. Wetlands Ecology and Management. Tobias, V.D., J.A. Nyman, R.D. DeLaune, and J.D. Foret. in press. Improving marsh restoration: leaf tissue chemistry identifies factors limiting production in Spartina patens. Plant Ecology. Tobias, V.D. J.A. Nyman, and J.D. Foret. in review. Developing critical values to improve diagnosis and management of flooding stress in marshes dominated by Spartina patens. Tobias, V.D. J.A. Nyman, and J.D. Foret. in preparation. Field trials of critical values to identify flooding stress, salinity stress, and nutrient limitation in marshes dominated by Spartina patens.

Next Step Find funding to produce the first map using these tools. Potential areas include –Management: Caernarvon outfall (roughly estimated at $150,000 in 2008) Cameron-Creole Watershed –Planning White Ditch South Pecan Island Andy Nyman, , or School of Renewable Natural Resources, Louisiana State University Agricultural Center

Developing a tool to map limiting factors to coastal wetland vegetation 1.grow plants under controlled salinity and nutrient conditions –develop chemical signatures for plants growing all four possible conditions: salinity-limited, nitrogen-limited, co-limited, and unlimited conditions 2.grow plants under controlled flooding and known salinity and nutrient conditions –develop chemical signatures for plants growing in all eight possible conditions: salinity-limited, nitrogen-limited, flood-limited, salinity & nitrogen limited, nitrogen and flood-limited, salinity and flood-limited, tri-limited, and unlimited conditions 3.challenge/validate chemical signatures with new data from the field

1. pre-CREST greenhouse study

H 0 : Aboveground and belowground biomass of S. patens will not differ among salinity and nutrient treatments. 1 populations # 66 and # 81 described by Hester et al American Journal of Botany 83: FactorsNLevels salinity (ppt)42, 6, 18, 36 soil nutrients (% of average)425, 75, 125, 200 tubs within each salinity/nutrient combination 4 populations 1 within tubs2 total pre-CREST greenhouse study

salinity stress more important than nutrient availability nutrient availability more important than salinity stress interaction: nutrient availability negates salinity stress interaction: salinity stress negates nutrient availability

1. pre-CREST greenhouse study

Neither NutrientBoth Salinity 1. pre-CREST greenhouse study

High Nutrients Low Nutrients Low Salinity High Salinity 1. pre-CREST greenhouse study

CREST-funded study

Grow Plants Under Controlled Flooding and Known Salinity & Nutrient Conditions use marsh organs to create a range of flooding stress place marsh organs is areas with different salinity and nutrient conditions

high salinity low salinity Grow Plants Under Controlled Flooding and Known Salinity & Nutrient Conditions

develop chemical signatures for plants growing in all eight possible conditions

CREST-Funded: Field Study challenge/validate the leaf-tissue tool using leaf tissue and porewater samples collected across the coast of Louisiana compare predictions of limiting factors based on landscape features to those identified by the leaf- tissue tool

Biomass –0.25m 2 clip plots Porewater –YSI- pH, conductivity, salinity, temperature –Hach Colorimeter- Ammonia-N, Ortho- Phosphate Tissue Stoichiometry – ICP: Na concentration –CHN Analyzer: C and N content CREST-Funded: Field Study

low nutrients high nutrients CREST-Funded: Field Study high salinity low salinity

low nutrients high nutrients CREST-Funded: Field Study high salinity low salinity

CREST-Funded: Field Study good news: leaf-tissue signatures developed in the experiments worked in the field; i.e., limiting factors identified via tissue analyses match nutrients and salinity measured in the field via pore water

CREST-Funded: Field Study

low nutrients high nutrients high salinity low salinity bad news: pore water analyses proves that even simple predictions such as this regarding landscape position, nutrient availability, and salinity are wrong

CREST-funded conclusions Stoichiometry of leaf tissue can be used to map flooding stress, salinity stress, and nutrient limitation in S. patens. Field trial of this tool reflected –seasonal differences in flooding stress, salinity stress, and nutrient availability –annual differences in flooding stress, salinity stress, and nutrient availability –spatial patterns in flooding stress, salinity stress, and nutrient availability that challenge of even simple, landscape-scale attempts to predict nutrient availability and salinity stress

collect 5 grams (about half a sandwich- sized ziplock bag) of “newest fully developed leaves if in plastic, then store on ice if in paper, then no ice needed oven-dry the leaves grind the dried leaves arrange for leaves to be analyzed for “Plant Environmental plus C and N” by the Soil Testing and Plant Analyses Laboratory (STPAL) at the LSU AgCenterSTPAL mail samples and $16/sample to STPAL use results to classify sample as flood- limited, salinity-limited, nitrogen-limited, or co-limited CREST-funded study: A Tool for Identifying Limiting Factors

Questions

CREST-funded study

c c b a DeLaune et al Wetlands 25:

ref man ref+fert man+fert Foret PhD Dissertation. University of Louisiana at Lafayette.