Sea level

Coastal mangrove forests are at risk of being submerged due to sea level rise (SLR). However, mangroves have persisted with changing sea levels due to a variety of biotic and physical feedback mechanisms that allow them to gain and maintain relative soil surface elevation. Mechanisms of surface elevation change (SEC) include leaf, wood, and root production, decomposition, and sedimentation/erosion, the combination of which result in a net change in the soil’s surface elevation. Therefore, mangrove forest resilience to SLR is dependent upon their ability to migrate inland or to build soil elevation at a rate that tracks with SLR. However, anthropogenic disturbances, such as altered hydrology and eutrophication, can degrade mangrove forest health and compromise their land building processes placing them at greater risk of succumbing to SLR.

Peatlands are areas with an accumulated layer of peat soil that are considered global stores of carbon, acting as a net sink of carbon dioxide and a net source of methane. Recent studies in coastal peatlands have shown how that a rise in sea level may contribute to the degradation of peat soils due to the inland progression of the saltwater interface, which may result in physical changes within the peat matrix that may eventually result in peat collapse. For example, earlier studies in boreal peat soils described the effect of pore dilation as a result of increased salinity in peat soils, while recent studies in Everglades peat soils showed specific salinity thresholds that may represent a permanent loss of the structural integrity of the peat matrix that may represent early stages of peat collapse. While most of these previous efforts have focused on drivers, recent work has also explored conceptual models to better understand the mechanisms inducing peat collapse. However, few datasets exists that consistently compare differences in physical properties under different in‐situ salinity conditions. In this study differences in the physical properties of peat soils across a salinity gradient along the western edge of Big Cypress National Preserve are investigated to test how differences in salinity may induce physical changes in the soil matrix. The physical properties targeted for this study include porosity, hydraulic conductivity, and carbon content. Measurements are conducted at the laboratory scale using peat cores and monoliths collected at selected locations to investigate: 1) how overall soil physical properties change spatially over a salinity gradient at the km scale moving from permanently saline to freshwater conditions; and 2) how physical properties change spatially at specific sites as dependant on vegetation boundaries and proximity to collapsed soils. This study has implications for better understanding the potential relation between physical changes of the soil matrix and the phenomena of peat collapse in the Everglades as saltwater intrusion progresses inward and alters freshwater ecosystems. Furthermore, a better mechanistic understanding of the peat collapse phenomenon can potentially help mitigate its occurrence.

As sea levels continue to rise, the projected damage that will ensue presents a great challenge for conservation and management of coastal ecosystems in Florida. Since Juncus roemerianus is a common marsh plant throughout Florida with unique growing characteristics that make it a popular restoration plant, this study implemented a 20 week greenhouse split plot experiment to examine the effects of sea level rise on J. roemerianus and ultimately determine its tolerance ranges to salinity and inundation in a high nutrient environment. Overall, salinity level and the interaction effect of salinity level and water level had the greatest effects on measured growth parameters including average mature height, maximum height, density, basal area, root length, and biomass. An inverse relationship between increasing salinity and the measured growth variables was observed with the greatest growth and survivability in 0 ppt water, survivability and reduced growth in 20 ppt water, survivability and little growth in 30 ppt water, and nearly complete senesce in 40 ppt water. This was the first laboratory study to determine the effect of 40 ppt water on J. roemerianus. Elevated water levels resulted in higher growth variables in the 20 ppt, 30 ppt, and 40 ppt treatments while inundated water levels produced higher growth variables in the 0 ppt treatment despite previous research finding inundation to have completely adverse effects on J. roemerianus. It is likely that the high nutrient environment provided for this study is the cause for this anomaly. The results of this study have major implications for the future of coastal ecosystems that are dominated by stands of J. roemerianus in South Florida and can be used in conjunction with studies on bordering marsh plants to predict shifts in the ecosystems of Florida that are responding to sea level rise scenarios.

Increasing sea levels have the potential to place important portions of the infrastructure we rely on every day at risk. The transportation infrastructure relies on roads, airports, and seaports to move people, services, and goods around in an ever connected global economy. Any disturbances of the transportation modes have reverberating effects throughout the entire economic spectrum. The effects include delays, alterations of routes, and possible changes in the origin and destinations of services and goods. The purpose of this project is to develop an improved methodology for a sea level rise scenario vulnerability assessment model. This new model uses the groundwater elevation as a limiting factor for soil storage capacity in determining previously underestimated areas of vulnerability. The hope is that early identification of vulnerability will allow planners and government officials an opportunity to identify and either remediate or create alternative solutions for vulnerable land areas before high consequence impacts are felt.