HABITAT RESILIENCY

Sea-level rise is expected be a major driver of habitat evolution in the CHNEP study area. Since most vegetation establishes in areas based on the local tidal inundation and salinity, habitats will evolve when the tides rise. Sea-level change scenarios predicted by the National Oceanic and Atmospheric Administration (NOAA 2017) were used for the CHNEP study area.

Zoom into area of interest and then use timeslider to view vegetative community shifts predicted based on likely climate scenarios. To use the timeslider to play an animation that steps through the data sequentially, press the left arrow on the timeslider. To step forward or backward in time, press the arrows on the right side of the time slider. Note that developed areas were not included in this habitat migration analysis and will remain unchanged in the model although they may be impacted as well.

• The habitat evolution model was developed for the CHNEP project area to predict the changes in vegetative communities through time. Changes in acreages of salt marsh, Juncus marsh, freshwater marsh, mangroves, and salt barren habitats were predicted and mapped on decade intervals.
• The model is based on an intermediate high sea level rise and a low accretion rate (low amount of sediment returning to shoreline) scenario. 
• Data including topography, vegetation and habitat, tides, projected sea-level rise from NOAA (2017), areas of freshwater influence, and habitat specific accretion rates were used to create the model. 

As you can see from this interactive chart, Intertidal habitat is expected to decrease dramatically over time. Mangroves will transgress into salt and freshwater wetland areas, followed by a decline in mangrove habitat at the end of this century and the beginning of next.

·        Tidal Flats are relatively open intertidal areas with a substrate of marl, mud, mud/sand, sand, or shell that lack dense populations of sessile plant and animal species. Tidal flats support tube worms, sand dollars, mollusks, isopods, amphipods, burrowing shrimp, and an assortment of crabs and are important feeding areas for resident and migrating shorebirds and other coastal wildlife.

·        Upland Developed Hard habitats are mostly covered by buildings and impermeable surfaces like roads and parking lots. Coastal armoring such as seawalls, riprap, revetments, bulkheads, retaining walls, or other means may be used to stabilize shoreline, which prevents habitat adaptation and migration.

·        Upland Developed Soft habitats have some development but also large open areas without structures and pavement. Their coastal edges may have living shorelines such as oyster reef, marsh and riparian plants, and other biodegradable material to protect against erosion while still allowing shorelines to adapt and transition with varying water levels.

·        Upland Undeveloped habitats are areas dominated by natural communities, devoid of permanent structures and roadways.

·        Open Water includes estuaries, rivers/streams, lakes/ponds, canals and the Gulf of Mexico.

·        Freshwater Marsh is permanently or seasonally flooded and is vegetated by grasses, sedges, broadleaf emergent plants, floating aquatic plants, and/or water-loving shrubs. Marshes are important habitat for reptiles and amphibians, insects, and wading birds.

·        Mangroves are trees with special adaptations that allow them to live in estuarine, intertidal areas. They protect the coasts by preventing soil erosion and by breaking the force of strong winds and waves caused by storms. Mangrove roots also make new land by trapping sand and leaves brought in by the tide. Mangrove roots offer hiding places for young fish and shellfish, and serve as roosting and nesting space for birds.

·        High Salt Marsh is covered by water only sporadically (once per day or less) and is characterized by salt-tolerant grasses and rushes. High salt marsh that is located at the landward edge is dryer and has more woody vegetation.

·        Juncus Marsh is an irregularly tidally flooded area characterized by dense patches of vegetation, dominated by black needlegrass (Juncus roemerianus) along with its associates: saltgrass (Distichlis spicata), smooth cordgrass (Sporobolus alterniflorus), saltmeadow cordgrass (Spartina patens), and carolina sea lavender (Limonium carolinianum). These marshes may be found as isolated patches within high salt marsh, or may dominate vast areas at the heads of tidal creeks.

·        Salt Barrens are hypersaline areas with little or no vegetation and are typically located along the upland fringes of mangrove forests or salt marshes, in upper intertidal areas that are inundated by tides only once or twice per month. Their high salt content is due to evaporation and the accumulation of residual salt, and varies seasonally with tidal inundation and rainfall. They are important feeding areas for wading birds and estuarine fish species.

·        Beach Dune is a predominantly herbaceous community of wide-ranging coastal specialist plants on the vegetated upper beach and first dune above the beach. Typical plant species are sea oats, railroad vine, bitter panicum, salt grass, inkberry, and beach elder. Plants are subject to wind to salt spray and sand burial from onshore winds blowing across the salt water and open sandy beach, as well as occasional inundation by high seasonal or storm tides and periodic destruction by waves.

Based on our model, by 2120, Freshwater Marsh, Juncus Marsh and Mangrove habitat will dramatically decrease and be converted to open water habitat. 

Policymakers, natural resource managers and the public can utilize this information to identify opportunities for further preservation and conservation of important habitat areas by working with willing private landowners, as well as where additional management, enhancement, and restoration is needed on public lands to improve their habitat value. Even greater benefits could be gained by identifying intensive development that may not be sustainable in the long-term for restoration as well. Projected sea level rise will put significant stress on tidal wetlands and cause habitats to transition to other types and/or shift geographically inland. Taking measures lessen sea level rise will reduce future habitat changes and potential losses.

Click for  Habitat Evolution Modeling Report