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Modelling forest management within a global vegetation model - Part 2: Model validation from a tree to a continental scale / V. Bellassen in Ecological modelling, vol 222 n° 1 (janvier 10, 2011)  

Public [article]  inEcological modelling > vol 222 n° 1 (janvier 10, 2011) . - pp 57 - 75 Titre : Modelling forest management within a global vegetation model - Part 2: Model validation from a tree to a continental scale Type de document : Article/Communication Auteurs : V. Bellassen, Auteur ; G. Le Maire, Auteur ; O. Guin, Auteur ; Jean-François Dhôte, Auteur ; Philippe Ciais, Auteur ; Nicolas Viovy, Auteur Année de publication : 2011 Article en page(s) : pp 57 - 75 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] biomasse forestière [Termes IGN] carbone [Termes IGN] modélisation de la forêt [Termes IGN] stress hydrique Mots-clés libres : ORCHIDEE-FM Résumé : (auteur) The construction of a new forest management module (FMM) within the ORCHIDEE global vegetation model (GVM) allows a realistic simulation of biomass changes during the life cycle of a forest, which makes many biomass datasets suitable as validation data for the coupled ORCHIDEE-FM GVM. This study uses three datasets to validate ORCHIDEE-FM at different temporal and spatial scales: permanent monitoring plots, yield tables, and the French national inventory data. The last dataset has sufficient geospatial coverage to allow a novel type of validation: inventory plots can be used to produce continuous maps that can be compared to continuous simulations for regional trends in standing volumes and volume increments. ORCHIDEE-FM performs better than simple statistical models for stand-level variables, which include tree density, basal area, standing volume, average circumference and height, when management intensity and initial conditions are known: model efficiency is improved by an average of 0.11, and its average bias does not exceed 25%. The performance of the model is less satisfying for tree-level variables, including extreme circumferences, tree circumference distribution and competition indices, or when management and initial conditions are unknown. At the regional level, when climate forcing is accurate for precipitation, ORCHIDEE-FM is able to reproduce most productivity patterns in France, such as the local lows of needleleaves in the Parisian basin and of broadleaves in south-central France. The simulation of water stress effects on biomass in the Mediterranean region, however, remains problematic, as does the simulation of the wood increment for coniferous trees. These pitfalls pertain to the general ORCHIDEE model rather than to the FMM. Overall, with an average bias seldom exceeding 40%, the performance of ORCHIDEE-FM is deemed reliable to use it as a new modelling tool in the study of the effects of interactions between forest management and climate on biomass stocks of forests across a range of scales from plot to country. Numéro de notice : A2011-285 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1016/j.ecolmodel.2010.08.038 Date de publication en ligne : 22/10/2010 En ligne : https://doi.org/10.1016/j.ecolmodel.2010.08.038 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102459 [article]

Voir aussi

• Modelling forest management within a global vegetation model - Part 1: Model structure and general behaviour / V. Bellassen in Ecological modelling, vol 221 n° 20 (octobre 2010)  

Modelling forest management within a global vegetation model - Part 1: Model structure and general behaviour / V. Bellassen in Ecological modelling, vol 221 n° 20 (octobre 2010)  

Public [article]  inEcological modelling > vol 221 n° 20 (octobre 2010) . - pp 2458 - 2474 Titre : Modelling forest management within a global vegetation model - Part 1: Model structure and general behaviour Type de document : Article/Communication Auteurs : V. Bellassen, Auteur ; G. Le Maire, Auteur ; Jean-François Dhôte, Auteur ; Philippe Ciais, Auteur ; Nicolas Viovy, Auteur Année de publication : 2010 Article en page(s) : pp 2458 - 2474 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] biomasse forestière [Termes IGN] carbone [Termes IGN] feuillu [Termes IGN] modèle de simulation [Termes IGN] modélisation de la forêt [Termes IGN] production primaire nette Mots-clés libres : ORCHIDEE Résumé : (auteur) This article describes a new forest management module (FMM) that explicitly simulates forest stand growth and management within a process-based global vegetation model (GVM) called ORCHIDEE. The net primary productivity simulated by ORCHIDEE is used as an input to the FMM. The FMM then calculates stand and management characteristics such as stand density, tree size distribution, tree growth, the timing and intensity of thinnings and clear-cuts, wood extraction and litter generated after thinning. Some of these variables are then fed back to ORCHIDEE. These computations are made possible with a distribution-based modelling of individual tree size. The model derives natural mortality from the relative density index (rdi), a competition index based on tree size and stand density. Based on the common forestry management principle of avoiding natural mortality, a set of rules is defined to calculate the recurrent intensity and frequency of forestry operations during the stand lifetime. The new-coupled model is called ORCHIDEE-FM (forest management). The general behaviour of ORCHIDEE-FM is analysed for a broadleaf forest in north-eastern France. Flux simulation throughout a forest rotation compare well with the literature values, both in absolute values and dynamics. Results from ORCHIDEE-FM highlight the impact of forest management on ecosystem C-cycling, both in terms of carbon fluxes and stocks. In particular, the average net ecosystem productivity (NEP) of 225 gC m−2 year−1 is close to the biome average of 311 gC m−2 year−1. The NEP of the “unmanaged” case is 40% lower, leading us to conclude that management explains 40% of the cumulated carbon sink over 150 years. A sensitivity analysis reveals 4 major avenues for improvement: a better determination of initial conditions, an improved allocation scheme to explain age-related decline in productivity, and an increased specificity of both the self-thinning curve and the biomass-diameter allometry. Numéro de notice : A2010-686 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1016/j.ecolmodel.2010.07.008 Date de publication en ligne : 20/08/2010 En ligne : https://doi.org/10.1016/j.ecolmodel.2010.07.008 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102452 [article]

Voir aussi

• Modelling forest management within a global vegetation model - Part 2: Model validation from a tree to a continental scale / V. Bellassen in Ecological modelling, vol 222 n° 1 (janvier 10, 2011)