Protocol implementation plan for monitoring mangrove soil surface elevation tables in South Florida / Caribbean Network parks

Whelan, Kevin

doi:10.36967/2230638

The mangrove forest ecosystem is a critical coastal resource in South Florida’s Biscayne National Park (BISC); Salt River Bay National Historical Site and Ecological Preserve (SARI) in St. Croix, U.S. Virgin Islands; and the Virgin Islands National Park (VIIS) in St John, U.S. Virgin Islands. Mangrove wetlands provide flood control, storm protection, shore stabilization, water filtration (capturing soil runoff), carbon sequestration, and habitat for fish and wildlife communities. The economic value of the services derived from mangroves has been estimated as high as $200,000–$900,000 ha-1 (United States Dollar [USD]) (Wells et al. 2006, Gilman et al. 2009). There is a feedback loop between soil elevation, hydrology, and mangrove forest health. The soil elevation level in mangrove forests affects tidal inundation period, tidal inundation frequency, and overall hydroperiod, all of which affect mangrove seedling species recruitment, composition, and survival (Whelan 2009). Additionally, mangrove forest hydrology affects soil processes such as sedimentation, erosion, and the shrink and swell of soil materials. Due to the importance of soil elevation to mangroves, it is critical to understand the rate of change in soil elevation to better predict the long-term ability of mangrove forests to regenerate. Therefore, the National Park Service (NPS) South Florida / Caribbean (SFCN) Inventory and Monitoring (I&M) Network is establishing a long-term soil surface elevation monitoring program in Biscayne, Salt River Bay, and Virgin Islands national parks as part of the Coastal Geomorphology Vital Sign, as part of the vital signs monitoring program. The program aims to monitor rates of soil accretion and erosion, and determine if soil processes are keeping pace with relative sea level (RSL) which has been measured at 1.1–1.9 mm yr-1 in South Florida (Maul and Martin 1993). If the RSL rate is greater than the rate at which mangrove soil elevation increases then the current mangrove forest will transgress upslope and the current areas occupied by mangrove forest will eventually convert to shallow open-water marine habitats as the trees die off and there is no recruitment to replace them. For resource managers, it will be important to understand how this process is affecting mangrove forest in their park units. Local long-term monitoring is necessary to develop this understanding. This plan outlines the means by which monitoring data will be collected, managed, and reported for the monitoring of Mangrove Soil Surface Elevation Tables in SFCN parks and park units, as described in the approved SFCN monitoring plan (Patterson et al. 2008). The South Florida / Caribbean Network is implementing the Southeast Coast Network’s (SECN) peer-reviewed and approved Protocol for Monitoring Coastal Salt Marsh Elevation and Vegetation Communities in Southeast Coast Network Parks (DeVivo et al. 2015) as it relates to soil elevation monitoring. The South Florida / Caribbean Network did not implement the soil salinity component or the marsh vegetation sampling. The modifications made to the sampling process are minor but reflect necessary changes to implement the SECN sampling protocol in the park units of our network. We deviated from the SECN peer-reviewed protocol for a few of the standard operating procedures (SOPs). For example, we drew from the Northeast Coastal and Barrier Network protocol Measuring and Understanding Wetland Elevation Change using the Surface Elevation Table (SET) and Marker Horizon Techniques (Lynch et al. 2015) because we are using their SET Microsoft® Access relational database.

Protocol implementation plan for monitoring mangrove soil surface elevation tables in South Florida / Caribbean Network parks

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