• Energy Research

AbstractBlack locust (Robinia pseudoacacia L.), a species native to the eastern North America, was introduced to Europe probably in 1601 and currently extends over 2.3 × 106 ha. It has become naturalized in all sub-Mediterranean and temperate regions rivaling Populus spp. as the second most planted broadleaved tree species worldwide after Eucalyptus spp. This wide-spreading planting is because black locust is an important multipurpose species, producing wood, fodder, and a source of honey as well as bio-oil and biomass. It is also important for carbon sequestration, soil stabilization and re-vegetation of landfills, mining areas and wastelands, in biotherapy and landscaping. In Europe, black locust is drought tolerant so grows in areas with annual precipitation as low as 500–550 mm. It tolerates dry, nutrient poor soils but grows best on deep, nutrient-rich, well-drained soils. It is a fast-growing tree and the height, diameter and volume growth peak before the age of 20. It mostly regenerates vegetatively by root suckers under a simple coppice system, which is considered the most cost-effective management system. It also regenerates, but less frequently, by stool sprouts. Its early silviculture in production forests includes release cutting to promote root suckers rather than stool shoots, and cleaning-respacing to remove low-quality stems, reduce the number of shoots per stool, and adjust spacing between root suckers. In addition, early, moderate and frequent thinning as well as limited pruning are carried out focusing on crop trees. The species is regarded as invasive in several European countries and its range here is expected to expand under predicted climate changes.

Climate change is a major driver of sustainable forest management change. In this paper, R&D engineers of the French National Forest Service reviewed several aspects of sustainable forest management in the light of climate change, in order to identify research and innovation priorities. Climate change may be addressed with various points of view: (i) impacts, risk prevention and crisis management; (ii) adaptation of forest management; (iii) contribution to mitigation through wood production and use; (iv) continuity and quality of ecosystem services. The state of the art and ongoing questions were outlined, according to the specific challenges of a public service managing 25% of the mainland forest area, supplying 40% of exchanged timber, and particularly concerned by different national and European policies (forestry-wood chain, climate change, biodiversity conservation, energy transition, natural risk mitigation and prevention, water). The horizon scan did not suggest obvious contradictions between the different points of view. It showed (i) the potential opportunities brought by innovations linked to bioeconomy (bio-based production chains and markets); (ii) the need for a more explicit and integrated statement of management objectives, especially those regarding timber use and conservation of biodiversity; (iii) the impact of concentrating R&D investments and innovations to support an active, diversified forest management, condition for continuously providing high-quality ecosystem services, mitigating risks and securing a sufficient supply to the forest industries. Le changement climatique structure la réflexion prospective sur la gestion durable des forêts, ses évolutions et les besoins d’innovation associés. L’Office National des Forêts présente ici une lecture de l’état des connaissances et des questions posées, à partir de laquelle il a défini ses priorités R&D: le travail a porté sur les principaux aspects de la gestion durable dans la définition de la Conférence d’Helsinki ; le contexte d’application est celui des forêts publiques françaises de métropole. Vis-à-vis du changement climatique, différents points de vue peuvent être adoptés : (i) impacts, prévention des risques et gestion des crises ; (ii) adaptation de la gestion ; (iii) contribution à l’atténuation via la production de bois ; (iv) continuité/qualité des services écosystémiques. L’analyse ne fait pas apparaître de contradictions entre ces différents points de vue, en revanche elle montre (i) les opportunités offertes par les innovations liées à la bioéconomie ; (ii) la nécessité de mieux expliciter les objectifs poursuivis (notamment dans la gestion de la biodiversité) ; (iii) l’intérêt de concentrer l’effort de R&D et innovation sur une série de leviers permettant une gestion active et diversifiée des forêts, gage de continuité des services écosystémiques, atténuation des risques et sécurisation des approvisionnements à la filière bois.

The current distribution area of the two sympatric oaks Quercus petraea and Q. robur covers most of temperate Western Europe. Depending on their geographic location, populations of these trees are exposed to different climate constraints, to which they are adapted. Comparing the performances of trees from contrasting populations provides the insight into their expected resilience to future climate change required for forest management. In this study, the descendants of 24 Q. petraea and two Q. robur provenances selected from sites throughout Europe were grown for 20 years in three common gardens with contrasting climates. The 2420 sampled trees allowed the assessments of the relationship between radial growth and climate. An analysis of 15-year chronologies of ring widths, with different combinations of climate variables, revealed different response patterns between provenances and between common gardens. As expected, provenances originating from sites with wet summers displayed the strongest responses to summer drought, particularly in the driest common garden. All provenances displayed positive significant relationships between the temperature of the previous winter and radial growth when grown in the common garden experiencing the mildest winter temperatures. Only eastern provenances from continental cold climates also clearly expressed this limitation of growth by cold winter temperatures in the other two common gardens. However, ecological distance, calculated on the basis of differences in climate between the site of origin and the common garden, was not clearly related to the radial growth responses of the provenances. This suggests that the gradient of genetic variability among the selected provenances was not strictly structured according to climate gradients. Based on these results, we provide guidelines for forest managers for the assisted migration of Quercus petraea and Q. robur provenances.

Même si la surface de la forêt française a progressé de 60 % en un siècle, la plaçant à la quatrième place au rang européen, que sa récolte a dans le même temps doublé (DENARDOU et al., 2017), cette forêt est confrontée àd’importants changements : climatiques, pouvant faire varier sa composition et son étendue spatiale ; sociétaux, avec de moins de moins de main-d’oeuvre en forêt simultanément à une prise de conscience des nombreux servicesécosystémiques rendus par ces espaces naturels ; mais surtout mondiaux avec la diminution des ressources fossiles, qui peuvent être pour partie remplacées par ce matériau polyvalent qu’est le bois.Pour relever ce défi conjoint de demandes plus fortes et plus différenciées sur la ressource, et de menaces importantes sur son évolution, quels sont les leviers à la disposition des gestionnaires de la forêt publique ?Il s’agit de présenter quelques pistes de travaux à l’interface entre recherche et gestion, qui explorent des solutions différenciées, mais ciblées sur des attentes des gestionnaires. La forêt publique est façonnée par l’homme depuis dessiècles, permettons-lui ensemble de s’adapter, et de nous aider à relever le défi d’une société plus sobre, valorisant les matériaux renouvelables, tout en continuant à assurer les multiples services écosystémiques. The area of French forest has grown by 60% in a century, and is at the fourth position at the European level; the harvest has doubled at the same time. However this forest is also facing important challenges: climatic (impact onforest composition and productivity, increase in frequency and intensity of forest disturbances), societal (decrease in forest workers and awareness rising of benefi ts and services to society provided by forest) and bioeconomic (decreasein fossil fuels resources and need of renewable materials). Wood is a versatile material which is renewable and can be used from construction, furniture to pulp and composite material, with a fi nal recycling in energy.To address this joint challenge of stronger and differentiated demands on wood resource and threats and constraints on the forest, some innovations and research of the public forest service are presented in this paper.

Arboretums have been used for decades for scientific, educational, horticultural and aesthetic purposes. Recently, climate change concerns have renewed the interest of the scientific community for these invaluable experimental forest systems. Here, we report a dataset from eight scientific arboretums planted in three contrasted French metropolitan bioclimates: Oceanic, Mountain and Mediterranean. In total, 92,236 trees were planted in 3,678 different plots. Originating from a worldwide range of habitats, from sea-level up to 3,670 m in elevation, the collection spans 711 forest tree taxa (species, subspecies and varieties) from 177 genera. Taxa often include several geographic sources (so-called provenances), often simultaneously in different arboretums, making within species analyses possible. Cool-climate temperate Pinaceae (pines, firs, spruces, hemlocks, etc.) are well represented in the Atlantic and Mountain arboretums while Mediterranean arboretums are particularly rich with genera from the Myrtaceae (mostly eucalypts) and the Pinaceae (mostly pines). Data include survival, growth (height and diameter) and health status. Planted between 1969 and 1976, 338 taxa had survived at time of assessment and occurred as at least one individual in one plot. Data can be used to assess species suitability for ecological restoration and afforestation, and to help improve functional niche modeling. Data accessibility: https://data.inrae.fr/dataset.xhtml?persistentId=doi:10.15454/RGMM07.

AbstractHow temperate forests will respond to climate change is uncertain; projections range from severe decline to increased growth. We conducted field tests of sessile oak (Quercus petraea), a widespread keystone European forest tree species, including more than 150 000 trees sourced from 116 geographically diverse populations. The tests were planted on 23 field sites in six European countries, in order to expose them to a wide range of climates, including sites reflecting future warmer and drier climates. By assessing tree height and survival, our objectives were twofold: (i) to identify the source of differential population responses to climate (genetic differentiation due to past divergent climatic selection vs. plastic responses to ongoing climate change) and (ii) to explore which climatic variables (temperature or precipitation) trigger the population responses. Tree growth and survival were modeled for contemporary climate and then projected using data from four regional climate models for years 2071–2100, using two greenhouse gas concentration trajectory scenarios each. Overall, results indicated a moderate response of tree height and survival to climate variation, with changes in dryness (either annual or during the growing season) explaining the major part of the response. While, on average, populations exhibited local adaptation, there was significant clinal population differentiation for height growth with winter temperature at the site of origin. The most moderate climate model (HIRHAM5‐EC; rcp4.5) predicted minor decreases in height and survival, while the most extreme model (CCLM4‐GEM2‐ES; rcp8.5) predicted large decreases in survival and growth for southern and southeastern edge populations (Hungary and Turkey). Other nonmarginal populations with continental climates were predicted to be severely and negatively affected (Bercé, France), while populations at the contemporary northern limit (colder and humid maritime regions; Denmark and Norway) will probably not show large changes in growth and survival in response to climate change.

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