Jean-François Dhôte’s research while affiliated with Office National des Forêts and other places

Ce numéro regroupe des textes issus des projets ayant travaillé dans le cadre du Programme PSDR 4, sous l’égide d’INRAE et de 10 Régions françaises.

This publication is the result of a study carried out by INRA (now INRAE, National Research Institute for Agriculture, Food and the Environment) and IGN (National Institute for Geographic and Forestry Information), at the request of the Ministry of Agriculture and Food and the High Council for Food, Agriculture and Rural Areas. It was conducted by INRAE’s Directorate for Collective Scientific Expertise, Foresight and Advanced Studies (DEPE). As with all work conducted by DEPE, this study was carried out according to the principles and rules for conducting expert assessments and studies laid down by this institution (INRAE-DEPE, 2018). DEPE carries out three types of projects, mostly commissioned by public authorities or external partners. • Collective Scientific Assessments (ESCo) involve the compilation of existing scientific knowledge to highlight achievements, uncertainties and knowledge gaps, and to reveal the latest scientific debates. • When the available literature is unable to precisely answer the questions posed by the public authorities, a multidisciplinary study-type approach is used. These studies are similar to the ESCo, and indeed integrate the ESCo approach, but complement it with the creation of new data (collection, statistical analysis, calculation and simulation). • Prospective studies offer visions of the future (or scenarios) for discussion by exploring, as systematically as possible, hypothetical scenarios based on available scientific knowledge. The study presented here includes elements specific to each of these three approaches. It examines how carbon balances can be established for the forestry and wood sector - taken here in its broadest sense, i.e. the entire forestry sector system and the activities related to the management, harvesting and value-adding of wood-based products - and their associated uncertainties. Firstly, it adopts an expert assessment approach using a review of the international scientific literature to define and discuss the assumptions and parameters to be adopted for each component along production chains that are likely to sequester or release carbon dioxide (CO2). The detailed results of this first stage were the subject of a first report directed to the ministry responsible for agriculture (Dhôte et al., 2015). This study also considers alternative forest management strategies up to 2050 using a prospective approach, which develops scenarios and seeks to quantify their long-term consequences. Finally, the study quantifies the effects of the scenarios considered using existing simulation tools, which therefore exposes their limitations. The detailed results of the complete study are available in the full report and its numerous annexes (see Roux et al., 2017). This project was coordinated by the project leader Alice Roux (INRAE-DEPE), and assisted by Marc-Antoine Caillaud and Kim Girard (INRAE-DEPE) who provided logistical and administrative support. The scientific steering was initially entrusted to Jean-François Dhôte (INRAE), with Antoine Colin (IGN) and Bertrand Schmitt, then Director of the DEPE (INRAE), taking over as planned and ensuring the finalization of the study and the coordination of this publication. To carry out this work, a group of experts, comprising researchers and technical experts from a variety of institutional and scientific backgrounds, was formed to cover the various themes addressed in the study. This group was composed of: Alain Bailly (FCBA[1]); Claire Bastick (IGN); Jean-Charles Bastien (INRAE); Alain Berthelot (FCBA); Nathalie Bréda (INRAE); Sylvain Caurla (INRAE); Jean-Michel Carnus (INRAE); Antoine Colin (IGN); Barry Gardiner (INRAE); Hervé Jactel (INRAE); Jean-Michel Leban (INRAE); Antonello Lobianco (AgroParisTech); Denis Loustau (INRAE); Benoît Marçais (INRAE); Céline Meredieu (INRAE); Luc Pâques (INRAE); Éric Rigolot (INRAE); Laurent Saint-André (INRAE). A summary of the expertise and contributions of each of the experts can be found at the end of the book. The supervision of the study was entrusted to a steering committee which brought together a group of administrative, technical and professional experts around the relevant units of the ministry responsible for agriculture, which commissioned the study. This process ensured constructive exchanges of different perspectives within the French forestry & wood sector. In addition to representatives of the Ministry of Agriculture, participants included: Pierrick Daniel, Lise Wlérick, Frédéric Branger and Florian Claeys (DGEP); Pierre Claquin and Élise Delgoulet (CEP); Sylvie Alexandre (MTES-MCT); Bernard Roman-Amat, then Michel Vallance (CGAAER); Jean-Luc Peyron (GIP Ecofor); Isabelle Feix and Miriam Buitrago (Ademe); Pierre Brender, Joseph Lunet and Elisabeth Pagnac-Farbiaz (MTES-DGEC); Gérard Deroubaix and Estelle Vial (FCBA); Christine Deleuze (ONF); Olivier Picard (CNPF-IDF); Jacques Chevalier (CSTB); Yves Duclerc (MTES-DHUP); Julia Grimault (I4CE). A first draft of this book greatly benefited from the constructive criticism of Erwin Dreyer (INRAE), Jean-Marc Guehl (INRAE), Mériem Fournier (AgroParisTech) and Jean-Luc Peyron (GIP Ecofor), whose comments were invaluable. Jean-Marc Guehl was also directly involved in the drafting process, helping us to place the approach used within the context of global forest issues in the face of climate change. Although the following is the sole responsibility of the authors of this publication, the contributions of the members of the steering committee and the scientific reviewers were important, both in the development of the study strategy and in the interpretations of the results. We would like to thank them all for their contributions. 1FCBA, l’Institut technologique Forêt cellulose bois-construction ameublement (The Technological Institute for Forest Cellulose, Timber and Wood Furniture).

Deux visions du rôle du secteur forestier dans la lutte contre le changement climatique semblent aujourd’hui s’opposer : l’une promeut l’accumulation de biomasse en forêt pour optimiser le stockage de carbone dans les écosystèmes forestiers ; l’autre préconise un accroissement des prélèvements de bois dans une approche large du développement de la bioéconomie. Si la première démarche mise sur le renforcement du « puits » forestier de carbone, la seconde vise à réduire les émissions de gaz à effet de serre dues aux activités humaines en substituant des produits bois aux biens dont les modes de production sont plus émetteurs.Centré sur l’exemple de la forêt française métropolitaine, cet ouvrage affine tout d’abord le bilan carbone de la filière forêt-bois et identifie les incertitudes liées à certains de ses paramètres clés. Puis, dans une démarche prospective, trois scénarios de gestion forestière, se différenciant par le niveau et les modalités des prélèvements de bois en forêt et par leur mode de gestion des boisements, ont été imaginés et leurs bilans carbone projetés jusqu’à l’horizon 2050. Les impacts sur ces bilans carbone d’une aggravation du changement climatique et de crises majeures, telles que des incendies, des tempêtes ou des invasions biologiques à grande échelle, ont été analysés. Issu d’une étude réalisée par INRAE et l’IGN à la demande du ministère chargé de l’Agriculture et de la Forêt et conduite par la Direction à l’expertise, à la prospective et aux études (DEPE) d’INRAE, cet ouvrage vise à éclairer le débat sur la façon dont la forêt et ses filières bois peuvent contribuer à atténuer le changement climatique.

Les forêts de l’hémisphère nord sont plus productives qu’il y a plusieurs décennies. Telle est la tendance observée et quantifiée dans différentes études menées depuis les années 1970 et qui mettent en cause plusieurs facteurs : les modifications des régimes pluviothermiques, les dépôts azotés et l’augmentation de la concentration atmosphérique en dioxyde de carbone. À partir de données de l’inventaire forestier national, les auteurs de cet article se sont penchés sur l’évolution des forêts françaises. Leurs résultats à des échelles plus fines mettent en évidence des variations extrêmes (négative et positive) liées aux espèces et au contexte environnemental local qu’il conviendrait de suivre en « temps réel » compte tenu des grandes incertitudes futures liées au climat.