Hypothesis 1: Changes in land-use and water allocation decisions in the South Florida Urban Gradient have hydrodynamic consequences in the Everglades landscape that explain observed changes in the oligohaline ecotone.
Approach - ? In FCE II, we quantified the spatial patterns of land use in (sub) urbanizing southern Miami-Dade Co. using satellite imagery to resolve land cover to the parcel scale, and connected land cover to neighborhood social composition at the census block group scale. In FCE III, we will extend our land-use change work to the full Everglades watershed, analyzing the past four decades of landscape change across the urban, suburban, and exurban/agricultural gradients using aerial photographs and multi-resolution satellite platforms (GeoEye, Landsat, MODIS). These analyses will provide spatially-explicit assessments of regional water flow patterns and connect them with land cover changes through time. We will further quantify urban and agricultural water demand by developing empirically calibrated water budgets (pilot budgets for southern Miami-Dade are currently being evaluated) for urban, suburban, agricultural, and other land covers within the Everglades watershed. To validate and refine our water demand and land-use analyses, we will collaborate with the Water CCT to survey urban and agricultural land managers (e.g., farmers, residential homeowners), ascertain their water use and land management practices, and elicit their experiences and perceptions of vulnerability to climate change. These land-use, water demand, and survey data will characterize the sensitivity of land users and the regional land-use system as it is exposed to hydrological changes due to climate variation and saltwater intrusion. We will also profile the adaptive capacity of the terrestrial-hydrological system in terms of water policy regimes, and thematically link past land-use changes with estimates of the relative SLR, climate cycles, and precipitation patterns from remote sensing and meteorological datasets tailored to our FCE land cover and hydrology databases to interpret sources of long-term variability in groundwater salinity in the Biscayne aquifer. These analyses of linked landscape-water-human system dynamics and the exposure, sensitivity, and adaptive capacity of the greater Everglades to climate variability and change will help us assemble a picture of system vulnerability to climate change.
Hypothesis 2: Legacies of changing freshwater inflows to the oligohaline ecotone have influenced sensitivity to the balance of fresh and marine water supplies across the landscape.
Approach - ? In addition to the datasets on land-use change and climate variability noted above, we will generate remote-sensing based vegetation indices to explore drivers of directional, cyclical, and stochastic change on salinity, nutrient concentrations, and C storage. Datasets include 20-50 yr salinity and nutrient concentrations at the mouth of the SRS and TS/Ph transects, 11+ yr of C flux data, and a suite of long-term (>150 yr) paleoecological datasets that have generated spatially-explicit C and nutrient accumulation or loss rates in or near the ecotone. In coordination with the Primary Production WG, we will derive and use vegetation indices from past and current multi-resolution remote sensing data (AVHRR, MODIS, Landsat) to evaluate whether vegetation indices can be combined with C flux data for gross primary production modeling (e.g., in estimating ecosystem light use efficiency), allowing us to scale up C dynamics from the plot to the landscape. We plan to examine connections between socio-hydrological and ecological processes using time-series analyses to identify and characterize their components (trend, cycles, breaks, seasonality), including the use of standardized cumulative sum charts (Z-cusum) to identify probable driver-response relationships of interest, confirm the significance of shifts with appropriate statistical tests and assess commonalities using time-series approaches. Statistical analyses and modeling (e.g., spatial regression, factorial ANOVA designs, multi-level modeling) will test relationships among indices of land cover, landscape structure, and climate-hydrological indicators at varied spatial scales to investigate boundary dynamics and neighborhood effects. These explorations of land-climate change legacies will position us to investigate additional, complex ecosystem science and policy questions in the future by identifying the critical pathways of change in the Everglades land-hydrologic system, and the critical feedbacks to the coupled system from ecosystem changes. In so doing, they will yield insights into the implications of land/water management dynamics for the sustainability of the integrated system, addressing the sensitivity of the Everglades system to climate change and further anthropogenic alteration. This work will also benefit from ongoing, cross-site research projects, including a newly funded study assessing the vulnerability of coastal mangroves in the Americas (including in the Everglades) to climate and anthropogenic change.