Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 8, 2263-2283, 2015
http://www.geosci-model-dev.net/8/2263/2015/
doi:10.5194/gmd-8-2263-2015
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Development and technical paper
28 Jul 2015
Improving the dynamics of Northern Hemisphere high-latitude vegetation in the ORCHIDEE ecosystem model
D. Zhu1, S. S. Peng1,2, P. Ciais1, N. Viovy1, A. Druel2, M. Kageyama1, G. Krinner2, P. Peylin1, C. Ottlé1, S. L. Piao3, B. Poulter4, D. Schepaschenko5, and A. Shvidenko5 1Laboratoire des Sciences du Climat et de l'Environnement, LSCE CEA CNRS UVSQ, 91191 Gif Sur Yvette, France
2UJF Grenoble 1, Laboratoire de Glaciologie et Géophysique de l'Environnement (LGGE, UMR5183), Grenoble, France
3Department of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
4Institute on Ecosystems and Department of Ecology, Montana State University, Bozeman, MT 59717, USA
5International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria
Abstract. Processes that describe the distribution of vegetation and ecosystem succession after disturbance are an important component of dynamic global vegetation models (DGVMs). The vegetation dynamics module (ORC-VD) within the process-based ecosystem model ORCHIDEE (Organizing Carbon and Hydrology in Dynamic Ecosystems) has not been updated and evaluated since many years and is known to produce unrealistic results. This study presents a new parameterization of ORC-VD for mid- to high-latitude regions in the Northern Hemisphere, including processes that influence the existence, mortality and competition between tree functional types. A new set of metrics is also proposed to quantify the performance of ORC-VD, using up to five different data sets of satellite land cover, forest biomass from remote sensing and inventories, a data-driven estimate of gross primary productivity (GPP) and two gridded data sets of soil organic carbon content. The scoring of ORC-VD derived from these metrics integrates uncertainties in the observational data sets. This multi-data set evaluation framework is a generic method that could be applied to the evaluation of other DGVM models. The results of the original ORC-VD published in 2005 for mid- to high-latitudes and of the new parameterization are evaluated against the above-described data sets. Significant improvements were found in the modeling of the distribution of tree functional types north of 40° N. Three additional sensitivity runs were carried out to separate the impact of different processes or drivers on simulated vegetation distribution, including soil freezing which limits net primary production through soil moisture availability in the root zone, elevated CO2 concentration since 1850, and the effects of frequency and severity of extreme cold events during the spin-up phase of the model.

Citation: Zhu, D., Peng, S. S., Ciais, P., Viovy, N., Druel, A., Kageyama, M., Krinner, G., Peylin, P., Ottlé, C., Piao, S. L., Poulter, B., Schepaschenko, D., and Shvidenko, A.: Improving the dynamics of Northern Hemisphere high-latitude vegetation in the ORCHIDEE ecosystem model, Geosci. Model Dev., 8, 2263-2283, doi:10.5194/gmd-8-2263-2015, 2015.
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This study presents a new parameterization of the vegetation dynamics module in the process-based ecosystem model ORCHIDEE for mid- to high-latitude regions, showing significant improvements in the modeled distribution of tree functional types north of 40°N. A new set of metrics is proposed to quantify the performance of ORCHIDEE, which integrates uncertainties in the observational data sets.
This study presents a new parameterization of the vegetation dynamics module in the...
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