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Our team is developing the Land Use and Carbon Scenario Simulator (LUCAS) model. LUCAS is a state-and-transition simulation model designed to track changes in land use, land cover, land management, and disturbance, and their impacts on ecosystem carbon storage and flux.

For more information visit the Land Use and Climate Change Team website. 

The LUCAS Model

The Land Use and Carbon Scenario Simulator (LUCAS) tracks changes in land use, land cover, land management, and disturbance, and their impacts on ecosystem carbon storage and flux.

The LUCAS model combines:

  • State-and-Transition Simulation Model to simulate changes in land-use across a range of geographic scales.
  • Stock and Flow Model to track the movement of carbon between different “pools” including interactions between land and atmosphere.
  • Linkage to the Integrated Biosphere Simulator (IBIS) dynamic global vegetation model.

 

State-and-Transition Simulation Models (STSM)

The STSM model is used to simulate changes in land use and land cover classes resulting from changes due to:

  • Urbanization
  • Agricultural expansion and contraction
  • Forest harvest, wildfire
  • Wildfire and other processes.

We use Monte Carlo methods to capture and reflect model and data uncertainties. We use an ecological framework known as ecoregions to stratify the United States into discrete units.

A diagram of the state and transition model for LUCAS

A diagram of the state and transition model for LUCAS (Public domain)

The LUCAS model was developed within ST-Sim , a free software tool built by ApexRMS, for developing and running STSMs. The SyncroSim wiki page provides more information on STSMs and getting started with ST-Sim. Also, check out this video on incorporating uncertainty into land-change projections with STSMs.

 

Stock and Flow Model

LUCAS carbon modeling is done using a simple stock-flow approach. Carbon pools are defined as a set of stocks, and flows are used to move carbon between stocks over time. We define two primary types of flows; automatic flows occur every year and include transfers of carbon from growth, mortality, and emission. Event-based flows are used to move carbon between stocks when a change in the land system occurs, such as removal of biomass from logging or urbanization. To parameterize the stock-flow model we use biogeochemical models, such as the Integrated Biosphere Simulator (IBIS) to derive regional carbon flux rates.

A diagram of stock and flux for IBIS carbon pools

A diagram of stock and flux for IBIS carbon pools (Public domain)