412-7 Validation and Inversion of a Carbon Net Ecosystem Exchange Model for Croplands.

Poster Number 302

See more from this Division: ASA Section: Climatology & Modeling
See more from this Session: Climatology & Modeling: II

Wednesday, November 18, 2015
Minneapolis Convention Center, Exhibit Hall BC

Michael Herbst1, Anne Klosterhalfen2, Marius Schmidt2, Lutz Weihermueller3, Alexander Graf4 and Harry Vereecken5, (1)Agrosphere Institute, Forschungszentrum Juelich GmbH, Julich, GERMANY
(2)Agrosphere, Forschungszentrum J├╝lich GmbH, Juelich, Germany
(3)Agrosphere Institute, Forschungszentrum Juelich GmbH, Juelich, GERMANY
(4)Agrosphere Institute, Forschungszentrum Juelich GmbH, Juelich, Germany
(5)Agrosphere Institute, IBG-3, Forschungszentrum Juelich GmbH, Juelich, Germany
Abstract:
Croplands play an important role in the carbon budget of many regions. However, the estimation of their carbon balance remains difficult due to the diversity and the complexity of the processes involved.

We report the coupling of a one-dimensional soil water, heat and CO2 flux model (SOILCO2) with a pool concept of soil carbon turnover (RothC) and with a crop growth module (SUCROS) for the prediction of carbon net ecosystem exchange (NEE). The coupled model, further referred to as AgroC, was extended with routines for managed grassland as well as for root exudation and root death.

In a first step the coupled model was applied to two winter wheat sites and an upland grassland in Germany. The models were validated in terms of soil water content, soil temperature, soil CO2 concentration, soil respiration, leaf area index, aboveground biomass and NEE measured with the Eddy covariance method. The overall model performance of AgroC was acceptable. Accounting for root exudation and root death improved model performance, which was tested with a dataset providing measured root and heterotrophic respiration.

In the second step the models were inverted and the effect of using either NEE measurements only or the combination of measured soil respiration and NEE was investigated. The estimated yearly carbon balance showed a distinct sensitivity towards the inclusion of soil respiration data in the inversion process. This was mainly attributed to the characteristics of the NEE measurements.

See more from this Division: ASA Section: Climatology & Modeling
See more from this Session: Climatology & Modeling: II