Here is a concise summary of the provided article:

### Summary of CLM2 Development

The article discusses the development of the Community Land Model (CLM2), which was created by building upon the earlier Common Land Model.

Key points:
- The NCAR Land Surface Model (LSM) was further developed to include carbon cycling, vegetation dynamics, and river routing capabilities.
- These advancements required modifications to the Common Land Model, including:
  - Replacing the biome-type land cover with a plant functional type (PFT) representation
  - Implementing vertical heterogeneity in soil texture
  - Incorporating a river routing model
  - Making numerous changes to parameterizations to meet energy and water balance requirements
- Initial coupling of CLM2 with the Community Atmosphere Model (CAM2) preserved most improvements seen in the Common Land Model.
- Further refinements and validation led to the release of CLM2 in May 2002 for use with CCSM2.
- Subsequently, changes were made to the model structure to represent carbon and nitrogen cycling, resulting in the release of CLM2.1 in February 2003.

Overall, the article details the evolution of the Community Land Model from the earlier Common Land Model, highlighting the key developments and modifications made to create the CLM2 and CLM2.1 versions.