[en] This article provides an assessment of the quantities of potentially exploitable timber in French forests, poplar plantations and hedges for the period 2007 to 2020. The first step consisted in computing the gross available quantities of timber, prior to deduction of the various current consumptions. This was done applying the reference silvicultural scenarios to all the plots in the French national forest inventory, on the basis of their features (species, structure, fertility, age, observed per hectare volume). Current consumption was then subtracted from these quantities. It was estimated using the annual sectoral 'forest exploitation' survey in industry and an estimation of fuelwood consumption by households. The outcome is an excess availability of more than 28 million cubic metres of timber per year for bio-energy or pulp uses, and nearly 15 million cubic metres of workable timber, essentially hardwoods. (authors)

[en] In the fight against global warming, plant biomass from forests is attracting growing interest. This fact sheet presents an estimate of forest biomass availability by major zone over the coming decade. The methodologies developed in the course of this work are original and constitute a result in themselves

[en] 

Background

Concern about climate change has motivated France to reduce its reliance on fossil fuel by setting targets for increased biomass-based renewable energy production. This study quantifies the carbon costs and benefits for the French forestry sector in meeting these targets. A forest growth and harvest simulator was developed for French forests using recent forest inventory data, and the wood-use chain was reconstructed from national wood product statistics. We then projected wood production, bioenergy production, and carbon balance for three realistic intensification scenarios and a business-as-usual scenario. These intensification scenarios targeted either overstocked, harvest-delayed or currently actively managed stands.

Results

All three intensification strategies produced 11.6–12.4 million tonnes of oil equivalent per year of wood-based energy by 2026, which corresponds to the target assigned to French wood-energy to meet the EU 2020 renewable energy target. Sustaining this level past 2026 will be challenging, let alone further increasing it. Although energy production targets can be reached, the management intensification required will degrade the near-term carbon balance of the forestry sector, compared to continuing present-day management. Even for the best-performing intensification strategy, i.e., reducing the harvest diameter of actively managed stands, the carbon benefits would only become apparent after 2040. The carbon balance of a strategy putting abandoned forests back into production would only break even by 2055; the carbon balance from increasing thinning in managed but untended stands would not break even within the studied time periods, i.e. 2015–2045 and 2046–2100. Owing to the temporal dynamics in the components of the carbon balance, i.e., the biomass stock in the forest, the carbon stock in wood products, and substitution benefits, the merit order of the examined strategies varies over time.

Conclusions

No single solution was found to improve the carbon balance of the forestry sector by 2040 in a way that also met energy targets. We therefore searched for the intensification scenario that produces energy at the lowest carbon cost. Reducing rotation time of actively managed stands is slightly more efficient than targeting harvest-delayed stands, but in both cases, each unit of energy produced has a carbon cost that only turns into a benefit between 2060 and 2080.

[en] A base for volume and biomass data of the aerial woody compartments of individual trees was constituted under the ANR EMERGE (French acronym for 'designing models for a robust, all-purpose estimation of wood energy') project by seven bodies involved in forest research and management in France (ONF, INRA, Cemagref, IFN, FCBA, CNPF and CIRAD) so as to come up with a robust model of woody resources in forests. These measurements, taken for various logging diameters, sometimes down to the slenderest branches, have been performed since the beginning of the 20. century forming a unique data base in France. The data cover a broad range of age groups, sizes, species, stand structures and environmental factors (soil, climate). Of particular interest is the distribution of the available data in relation to French resources as estimated in the National Forest Inventory so as to use sampling campaigns to collect missing information under the EMERGE project. Another significant feature is the potential for designing robust, all-purpose models of volumes and biomass for various logging diameters depending on species, stage of development, geographic gradients, variations in silvicultural practises and possible effect of date of measurement. (authors)

[en] This study describes an example of empirical biomass models devised for beech that meet the standards of exhaustiveness (branches and slender logging diameters included), performance (maximum accuracy of evaluation) and robustness (in respect of changes in productivity and silvicultural practises). This level of accuracy was achieved by adding stand age to the conventional explanatory variables in biomass models (diameter at 1.30 m and total tree height) and using a form of allometric equation that links the parameters in the model to the biological phenomena that govern tree growth. These models were applied to a chrono-sequence located in Brittany. The results obtained were compared to the Bouchon's volume tables (1982) currently in use by forest managers to estimate biomass stocks. It appears that tools currently being used on the ground significantly underestimate the stocks from the tree crowns which account for the largest source capable of satisfying wood energy needs. Concerning national carbon stock estimations, applying biomass equations increases their accuracy by 10 % compared to first computing volume followed by mass. (authors)

[en] This report describes and discusses the perspectives of evolution and innovation for three great issues related to renewable energies. The first one is waste methanization, and the report addresses the following topics: practice in France, characterization of organic wastes, quick prediction of the potential associated with solid wastes, integration of methanization within an existing sector, local implantation of methanization, towards the methanization of sewage sludges, for a better management of digestates, the issue of renewability of our wastes, the optimization of microbial processes of waste degradation, analysis of methanization life cycle). The second issue is the use of wood as energy source: quantities, cartography of forest biomass by remote sensing, cartography of exploitability in mountain forests, organisation of a wood-energy supply, cartography of clear cuts, impacts of wood crops on insects, producing more wood while better preserving biodiversity, wood-energy governance. Thirdly, the report addresses issues of energy savings and impacts: energy optimization for agricultural machinery, relationship between irrigation and energy saving, energy saving by energy storage, nebulisation applied to refrigeration equipment, high thermal inertia applied to domestic refrigerators, works and downstream migration of eel, dam hydraulic management and fish population dynamics, reduction of environmental print at work

[en] The energy crisis and predicted global warming are opening up new prospects for the use of forest biomass. France has made a commitment within Europe to increase the proportion of renewable energy in total energy consumption to 23% by 2020, i.e. a threefold increase on the current situation. Much of the biomass used will come from forests, for which the Grenelle Environmental Forum set a target of 20 Mm³ additional harvest by 2020, i.e. a 30% increase on the current situation. In addition, France is committed, alongside other European countries and within the framework of the Convention on Biological Diversity adopted in 1992, to 'halting the loss of biodiversity by 2010', and the 'Grenelle de l'Environnement' itself is committed to preserving forest biodiversity. The possibility of reconciling the objectives of increasing biomass production and conserving biodiversity was discussed as part of the Grenelle Environmental Forum, which saw the major forestry partners agree on the objective of 'producing more (wood) while better preserving (biodiversity)' as part of 'a concerted territorial approach respecting the multifunctional management of forests'. At the request of the French Ministry for the Environment, GIP Ecofor has coordinated a collective study to summarize the potential implications of increasing the use of forest biomass on biodiversity and natural resources (soil and water) in mainland France. The study covered: - the context, forest biomass utilization prospects and forestry development scenarios to be expected in the medium term; - the possible impact of these developments on wood resources, forest biodiversity, forest soils and surface waters; - the recommendations that can be made to control the main risks and organize governance so as to effectively harvest more wood while preserving the forest environment and its biodiversity; - opportunities associated with favorable conditions for the use of biomass. The study did not address, except very partially, the world of micro-organisms, insect pests and pathogenic fungi, the intraspecific variability of forest trees, and more generally 'functional' biodiversity, ecosystem functioning (mineral element flows, etc.), the link with climate change, and the case of tropical forests