Documents - Proposals - GCE Proposals

Abstract - The overall goal of the Georgia Coastal Ecosystems (GCE) Long-Term Ecological Research program is to understand estuarine and intertidal ecosystems and how they respond to long-term change. Since the program began in 2000 the Principal Investigator (PI) team has established a robust program of long-term field observations, experiments, remote sensing, and modeling to understand wetland ecosystem functioning. The PIs will build on this in GCE-V, but with an overlay of new efforts focused on variability. The GCE-V project has 5 programmatic areas that map onto objectives (obj). Obj. 1 is to characterize spatial and temporal patterns in mean and variability of drivers and responses. This will be done by measuring external drivers (e.g., sea level), marsh and estuarine conditions, the wetland biophysical template, and modeling. Obj 2 is to evaluate linkages between external drivers and ecological responses, and determine whether assessing the variability of abiotic drivers improves explanatory power for predicting those responses. This will be done by analyzing long-term data and conducting field campaigns in areas with different salinity standard deviations and time-varying inundation, and complementary mechanistic experiments exploring effects of driver variability (e.g., salinity). Obj. 3 is to assess disturbances and their effects on patterns of variability in ecological responses. This will be done by tracking response to and recovery from natural disturbances in the field and in ongoing experimental manipulations. Obj. 4 is to evaluate how ecological properties change across abiotic gradients, and determine whether variability increases near habitat transitions. This will be done using remote sensing, sampling across gradients of salinity and inundation, and establishing new long-term monitoring sites in forested areas to track upland marsh migration. Obj. 5 is to determine the mechanisms by which coastal wetlands respond to changing drivers and assess whether variability informs this understanding. This will be done by conducting univariate and multivariate analyses relating key ecosystem variables (e.g., net ecosystem exchange, plant biomass) to drivers (salinity, inundation, temperature), using remote sensing to investigate spatial and temporal patterns in the mean and variability of marsh productivity and their relationship to variability in climate drivers, and synthesizing results to describe net daytime production and above- and below-ground C stocks and how they might change in response to future conditions.

Abstract - The Georgia Coastal Ecosystems (GCE) LTER program, which is located along three adjacent sounds on the Atlantic coast, was established in 2000. GCE research focuses on long-term change in estuarine and intertidal wetland ecosystems. In GCE-IV we will focus on disturbance. Our specific goals are to: 1) Track environmental and human drivers that can cause perturbations in our focal ecosystems. We will accomplish this through continuing long-term measurements of climate, water chemistry, oceanic exchange, and human activities on the landscape. 2) Describe temporal and spatial variability in physical, chemical, geological and biological characteristics of the domain and how they respond to external drivers. We will accomplish this through our field monitoring program in combination with remote sensing and modeling. 3) Characterize the ecological responses of intertidal marshes to disturbance. We will accomplish this by ongoing monitoring and experimental work to evaluate system response to major perturbations in three key marsh habitats (changes in inundation and top-down control in Spartinadominated salt marshes; increases in salinity in fresh marshes; changes in runoff in high marshes), by implementing standardized experimental disturbances along salinity and elevation gradients, and by tracking responses to natural disturbances. 4) Evaluate ecosystem properties at the landscape level (habitat distribution, net and gross primary production, C budgets) and assess the cumulative effects of disturbance on these properties. We will also develop relationships between drivers and response variables, which can be used to predict the effects of future changes. We will accomplish this through a combination of data synthesis, remote sensing and modeling.

Abstract - The Georgia Coastal Ecosystems (GCE) LTER is located along three adjacent sounds on the Atlantic coast and includes both intertidal marshes and estuaries. Long-term drivers of climate change, sea level rise and human alterations of the landscape will cause transitions in dominant habitat types (state changes) within the GCE domain by changing the amounts and patterns of water delivery across the landscape. These changes in water delivery can be conceptualized as presses and pulses in river inflow, local runoff, groundwater input, and tidal inundation, which will in turn manifest themselves as changes in salinity and inundation patterns in the domain. The research proposed for GCE-III is designed to address how variations in salinity and inundation, driven by climate change and anthropogenic factors, affect biotic and ecosystem responses at different spatial and temporal scales, and to predict the consequences of these changes for habitat provisioning and carbon (C) sequestration across the coastal landscape.

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