Robert R. Twilley
The proposed work has eight major objectives:
1. Re-measurement and analysis of mangrove permanent plots 10 years after the passage of Hurricane Andrew to verify forest structure models (SELVA-MANGRO) and to re-calibrate output accordingly. 2. Map historic marsh-mangrove ecotone boundaries in selected southwest Florida regions. 3. Survey land/water datums across the intertidal and develop tidal ebb/flow synoptic functions for incorporation into SELVA-MANGRO. 4. Site quality characterization across the mangrove landscape using ground surveys and research studies, aerial photography, and aerial videography. 5. Develop external SELVA-MANGRO model linkages and WEB-based access to SELVA-MANGRO for Everglades restoration evaluations. 6. Verify HYMAN (hydrology), NUMAN (nutrient/organic matter decomposition), and FORMAN (forest structure/primary productivity) unit ecological simulation models with application to Everglades restoration evaluations. 7. Link SALSA (Hydrology BOX model) to HYMAN and FORMAN models to develop a better link between vegetation response and hydrological fluxes to the Everglades system. 8. Conduct field and greenhouse studies on nutrient biogeochemistry and determine the effects of nutrients and hydroperiod on forest biomass allocation and soil formation.
700 Cajundome Blvd.
Twilley, R. R.
Twilley, R. R.
Smith, T. J. III Robblee, M. B.
Girod, G. F.
H. F. Diaz and R. S. Pulwarty, editors
M. Messina and W. Connor, editors
C. Hall, editor
Twilley, R. R.
Work planned for FY 2003 includes: A large percentage of the work conducted during the remainder of 2001 and into 2002 involves computer programming tasks aimed at increasing the functionality and user friendliness of SELVA-MANGRO. Current efforts are focused on model programming upgrades to the newest version of C++, formatting and serving SELVA-MANGRO on an internally housed WEB server, and verification of model simulations from Everglades mangrove field data summaries.
During this year, we also expect to advance our ecotone mapping efforts considerably. This will include mosaicing 1952 and 1992 aerial photos from selected regions, digitizing ecotone boundaries, and conducting area change analysis.
In order to link forest structural attributes to proposed changes in hydrology, we have installed a series of productivity studies (using mangrove dendrometry as a proxy for growth) along a hydroperiod continuum in southwest Florida that we plan to monitor throughout the next year and beyond. Monitoring will include measurements of growth, porewater salinity, and hydroperiod. Each site has a waterlevel recorder within the mangrove forest that is downloaded quarterly. We also plan to install several field ecophysiological investigations in an attempt to relate flooding effects to a mature tree physiological mechanism (i.e., xylem sap flow) and response, which will create a necessary hydroperiod link to forest stand evaportranspirational and growth characteristics. Seedling growth and physiological characteristics will be measured in greenhouse experiments already underway. Parameters will include biomass partitioning, transpiration, and photosynthetic carbon assimilation.
700 Cajundome Blvd.
After building a user-friendly C++ interface for each of the NUMAN (organic matter decomposition), FORMAN (primary productivity), and HYMAN (hydrology) models during May to August 2002, we will focus our efforts on connecting all these models within a general mangrove model (MANGAL). We are planning to make the MANGAL model locally available (C++ platform), although will be exploring the possibility of internet-based access similar to the SELVA-MANGRO model (Task 1). We will be developing new interactions among the three sub-models and validating parameters based on information gathered during ongoing field studies in the Shark and Taylor River Sloughs. Field studies to calibrate MANGAL will include measuring mangrove primary productivity (monthly litter fall collections), fine root production (ingrowth cores), sedimentation rates (lead and cesium isotopes), soil and pore water nutrient concentrations, and hydroperiod. These studies are also part of the LTER project (2000-2003) coordinated by Florida International University.
Given the importance of hydrology as a major component of the restoration plan for the Everglades region, we will continue our efforts to develop box models. These box models are useful to evaluate changes in salinity and hydroperiod as freshwater flow is modified upstream. We will continue validating a box model for the Shark River (SALSA) using data collected during dry and rainy conditions from 2001-2003, and building a similar model for Taylor River Slough. For the Taylor River Slough box model, we will be collaborating with Dr. W. K. Nuttle (Cadmus Group) and Dr. Chris Madden (SFWMD).
We will also continue greenhouse experiments testing the effects of salinity, water level, nitrogen concentrations, and phosphorous concentrations on seedling growth rates for Laguncularia racemosa, Rhizophora mangle, and Avicennia germinans. These experiments will provide growth functions for the productivity module (FORMAN) of the MANGAL model. In addition, we will be continuing our field studies of mangrove forest structure to determine succession patterns along the Shark and Taylor Rivers to verify FORMAN and MANGAL model outputs. Conceptual models of mangrove successional patterns are critical in selecting performance measures for the “Mangrove” component of the RECOVER monitoring and assessment program.
700 Cajundome Blvd.
U.S. Department of the Interior, U.S. Geological Survey, Center for
Coastal Geology
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