International workshop on

  
Koli (c) Metla/Erkki Oksanen

Development of Models and Forest Soil Surveys for Monitoring of Soil Carbon

April 5-8, 2006 at Koli, Finland
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Soil Carbon Model Parameterization and the Equilibrium Assumption

Thomas Wutzler

Max Planck Institute for Biogeochemistry, Hans-Knöll-Straße 10, 07745 Jena, Tel +49 3641 576104,
e-mail: thomas.wutzler@bgc-jena.mpg.de

The soil carbon model YASSO well captures important features of soil carbon changes. Because of its simplicity it is suited for integration with inventories and various forest growth models. The Parameterization of the YASSO model was based on the assumption of soil carbon stocks to be at or near equilibrium. However, many forest soils in central Europe are recovering from degradation of former intensive usage (e.g. former agricultural use, cattle drift, or litter raking).

We present an approach of parameterization of the YASSO model that is based on a weaker assumption. The pool with the slowest turnover rate is exempted from the equilibrium assumption. The approach requires the knowledge of the current rate of change in soil carbon stocks. We assumed that this rate could be estimated by a repeated soil carbon inventory.

However, this method will not detect small changes.

Already small rates of current change of soil carbon stocks result in a huge changes in total equilibrium stocks. These stocks represent the potential carbon storage after thousands of years with same inputs and environmental conditions. This way of parameterization does not change the short term carbon dynamics. However, there are long term consequences on carbon dynamics and the potential ability of forest soils to act as a significant carbon sink.

 
   Päivitetty:   02.03.2006 / EKel Metla : Events   Palaute Metlan etusivulle
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