What is the NECN Succession Extension?

The Net Ecosystem Carbon and Nitrogen (NECN) Succession extension was designed to provide total ecosystem accounting of Carbon and Nitrogen and to allow species to respond dynamically to a changing climate via establishment and growth. NECN calculates how cohorts grow, reproduce, age, and die. Dead biomass is tracked over time, divided into four pools: surface wood, soil wood (dead coarse roots), surface litter (dead leaves), and soil litter (dead fine roots). In addition, three principle soil pools: fast (soil organic matter (SOM) 1), slow (SOM2), and passive (SOM3) are simulated, following the Century soil model.

Recent Additions

• [x] New with v8

  • [ ] Species and Functional Group tables have been merged

• [x] New with v7

  • [ ] Integrated drought mortality via an optional table that defines statistical relationships
  • [ ] Updated soil water algorithms that improves low moisture estimates
  • [ ] New continuous function for estimating regeneration, given light, that requires fewer parameters
  • [ ] Optionally capacity to modify PET according to topography
  • [ ] Establishment can now optionally be reduced according to climatic water deficit and/or soil drainage
  • [ ] Growth as a function of soil water now has an optional functional form that is more flexible, better able to account for wet soils
  • [ ] Simulates grass species and their interactions with regeneration.

Standard Features

• [x] Estimate Net Ecosystem Exchange.
• [x] Estimate Actual and Potential Evapotranspiration, Climatic Water Deficit, and Available Soil Water.
• [x] Estimate smoke emissions from wildfires and prescribed fires.
• [x] Species parameters input as CSV delimited files.
• [x] Estimate Soil Organic Carbon, Soil Nitrogen, Nitrogen fluxes

Citation

Scheller, R.M., D. Hua, P.V. Bolstad, R. Birdsey, D.J. Mladenoff. 2011. The effects of forest harvest intensity in combination with wind disturbance on carbon dynamics in a Lake States mesic landscape. Ecological Modelling 222: 144-153.

Release Notes

• Latest official release: Version 8.3.1 — June 2026
• NECN User Guide.
• User Guide for Climate Library
• Full release details found in the NECN User Guide and on GitHub.
• This extension was formerly named Century Succession.

Requirements

To use NECN, you need:

• The LANDIS-II model v8.0 installed on your computer.
• Example files (see below)

Download and Install the Extension

• The latest version can be downloaded from GitHub. (Look for the download icon in the upper right corner.)
• Launch the installer.

Example Files

LANDIS-II requires a global parameter file for your scenario, and then different parameter files for each extension.

Landscape example files are here.

Single-cell example files are here.

Support

If you have a question, please contact Robert Scheller. You can also ask for help in the LANDIS-II users group.

If you come across any issue or suspected bug when using NECN, please post about it in the issue section of the Github repository.

Author

Robert Scheller