Imperiled Ecosystems in a Shifting Climate
2016 Atlantic White Cedar Symposium
May 24-26, 2016

Hotel 1620, 180 Water St., Plymouth, MA

Evaluating the Carbon Dynamics of Atlantic White-Cedar Peatlands in the Great Dismal Swamp: A State-and-Transition Simulation Modeling Approach

Authors: Rachel R. Sleeter, Dianna Hogan, Benjamin M. Sleeter, Emily Pindilli, Brianna Williams
U.S. Geological Survey, Eastern Geographic Science Center; rsleeter@gmail.com

The Great Dismal Swamp (GDS) Carbon Project is a multi-disciplinary effort between the U.S. Geological Survey and the U.S. Fish and Wildlife Service with the primary objective of understanding how to maximize carbon sequestration on public lands while assessing the potential tradeoffs among competing ecosystem services. The GDS is a highly altered landscape, where peatlands, once dominant with Atlantic white cedar [Chamaecyparis thyoides (L.) B.S.P.] (AWC), have been ditched, drained, and logged, causing drying and oxidation of peat soils and increasing ecosystem vulnerability.  As a consequence, natural disturbances such as fire have a higher probability of escalating into catastrophic events, resulting in deep peat burns and large CO2 emissions.  To quantify the terrestrial carbon dynamics of the GDS landscape we use the Land Use and Carbon Scenario Simulator (LUCAS), a model developed by the U.S. Geological Survey using the ST-Sim software package. LUCAS integrates a state-and-transition simulation model with a carbon stock-flow model to estimate the future impacts of land-use, land-management, and disturbance regimes on terrestrial carbon dynamics.  The LUCAS  structure organizes the landscape spatially into a grid of simulation cells that represent baseline biophysical conditions as a combination of vegetation type (AWC, Pine Pocosin, Maple Gum, Cypress Gum), stand age, and moisture zone (soil saturation). Spatial and temporal transitions between competing vegetation types are associated with probabilities of disturbances (i.e., drainage, logging, wildfire, hurricanes, drought, and invasion) and/or management actions (i.e., re-wetting, re-planting, prescribed burn, and herbicide application). Recent in situ biomass measurements are paired with literature-based values of carbon flow rates to parameterize the carbon stock-flow model and enable the evaluation of carbon stock as a function of land management. Through stakeholder participation at the GDS National Wildlife Refuge, five exploratory scenarios have been developed, ranging from reference conditions with no management, to various levels of increased disturbance conditions and increased management actions.  Spatially-explicit results from all five scenarios are intended to be used by GDS stakeholders to inform the decision-making process relative to priority ecosystem services like carbon sequestration, biodiversity, fire mitigation, nutrient cycling, and flood protection. 

Disclaimer
Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Rachel Sleeter is a Geographer under the Eastern Geographic Science Center at the USGS National Center. She has been a USGS employee for 16 years and lives on the West Coast (Gig Harbor, Wa.), working remotely. Rachel Sleeter was brought on the the Great Dismal Swamp Project 2 years ago to lead the integrated modeling development, where carbon balance and ecosystem response to disturbance and land management can be evaluated. Rachel will be presenting her talk titled, "Evaluating the carbon dynamics of Atlantic White Cedar peatlands in the Great Dismal Swamp: A state-and-transition simulation modeling approach"