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European beech (Fagus sylvatica L.) is one of the most economically and ecologically important deciduous trees in Europe, yet little is known about its genomic diversity and its adaptive potential. Here, we detail the discovery and analysis of 573 single nucleotide polymorphisms (SNPs) from 58 candidate gene fragments that are potentially involved in abiotic stress response and budburst phenology using a panel of 96 individuals from southeastern France. The mean nucleotide diversity was low (θ π = 2.2 × 10-3) but extremely variable among gene fragments (range from 0.02 to 10), with genes carrying insertion/deletion mutations exhibiting significantly higher diversity. The decay of linkage disequilibrium (LD) measured at gene fragments >800 base pairs was moderate (the half distance of r 2 was 154 bp), consistent with the low average population-scaled recombination rate (ρ = 5.4 × 10-3). Overall, the population-scaled recombination rate estimated in F. sylvatica was lower than for other angiosperm tree genera (such as Quercus or Populus) and similar to conifers. As a methodological perspective, we explored the effect of minimum allele frequency (MAF) on LD and showed that higher MAF resulted in slower decay of LD. It is thus essential that the same MAF is used when comparing the decay of LD among different studies and species. Our results suggest that genome-wide association mapping can be a potentially efficient approach in F. sylvatica, which has a relatively small genome size. © 2013 Springer-Verlag Berlin Heidelberg.

The accessibility of high-throughput genotyping technologies has contributed greatly to the development of genomic resources in non-model organisms. High-density genotyping arrays have only recently been developed for some economically important species such as conifers. The potential for using genomic technologies in association mapping and breeding depends largely on the genome wide patterns of diversity and linkage disequilibrium in current breeding populations. This study aims to deepen our knowledge regarding these issues in maritime pine, the first species used for reforestation in south western Europe. Using a new map merging algorithm, we first established a 1,712 cM composite linkage map (comprising 1,838 SNP markers in 12 linkage groups) by bringing together three already available genetic maps. Using rigorous statistical testing based on kernel density estimation and resampling we identified cold and hot spots of recombination. In parallel, 186 unrelated trees of a mass-selected population were genotyped using a 12k-SNP array. A total of 2,600 informative SNPs allowed to describe historical recombination, genetic diversity and genetic structure of this recently domesticated breeding pool that forms the basis of much of the current and future breeding of this species. We observe very low levels of population genetic structure and find no evidence that artificial selection has caused a reduction in genetic diversity. By combining these two pieces of information, we provided the map position of 1,671 SNPs corresponding to 1,192 different loci. This made it possible to analyze the spatial pattern of genetic diversity (H e ) and long distance linkage disequilibrium (LD) along the chromosomes. We found no particular pattern in the empirical variogram of H e across the 12 linkage groups and, as expected for an outcrossing species with large effective population size, we observed an almost complete lack of long distance LD. These results are a stepping stone for the development of strategies for studies in population genomics, association mapping and genomic prediction in this economical and ecologically important forest tree species.

Social interactions among individuals are widespread, both in natural and domestic populations. As a result, trait values of individuals may be affected by genes in other individuals, a phenomenon known as indirect genetic effects (IGEs). IGEs can be estimated using linear mixed models. The traditional IGE model assumes that an individual interacts equally with all its partners, whether kin or strangers. There is abundant evidence, however, that individuals behave differently towards kin as compared with strangers, which agrees with predictions from kin-selection theory. With a mix of kin and strangers, therefore, IGEs estimated from a traditional model may be incorrect, and selection based on those estimates will be suboptimal. Here we investigate whether genetic parameters for IGEs are statistically identifiable in group-structured populations when IGEs differ between kin and strangers, and develop models to estimate such parameters. First, we extend the definition of total breeding value and total heritable variance to cases where IGEs depend on relatedness. Next, we show that the full set of genetic parameters is not identifiable when IGEs differ between kin and strangers. Subsequently, we present a reduced model that yields estimates of the total heritable effects on kin, on non-kin and on all social partners of an individual, as well as the total heritable variance for response to selection. Finally we discuss the consequences of analysing data in which IGEs depend on relatedness using a traditional IGE model, and investigate group structures that may allow estimation of the full set of genetic parameters when IGEs depend on kin.

Partant du constat que la majorité des espèces exotiques d’insectes introduites en Europe viennent désormais d’Asie, l’INRA a testé dans le cadre de plusieurs projets européens l’intérêt de plantations « sentinelles »d’arbres européens sur deux sites en Chine. La colonisation de ces arbres « sentinelles », appartenant à sept essences communes des forêts d’Europe,par les ravageurs indigènes chinois a été surveillée de 2008 à 2012. Plus d’une centaine d’espèces d’insectes phytophages ont ainsi été observées et 39 d’entre elles constituent une menace potentielle, en particulier pour les chênes pédonculés. La généralisation d’une telle méthode, alliée à la mise en place de diagnostics moléculaires permettant d’identifier les espèces au stade œuf ou larve, pourrait constituer un outil d’identification précoce des espèces potentiellement dangereuses pour les forêts européennes., Because most alien insect species introduced to Europe nowadays originate from Asia, INRA established sentinel plantings of European trees in two locations of China in order to test their potential for an early warning of future invaders. In the course of several EU projects, the colonization by native Chinese insects of these sentinel trees, which belonged to seven widespread species of European forests, was surveyed from 2008 to 2012. More than one hundred phytophagous insect species were observed of which 39 may constitute a potential threat especially for pedunculate oak.This method, associated to the definition of diagnostic molecular markers allowing an identification of species at immature stages of development (egg, larva), may constitute a valuable tool for an early identification of potential pest invaders susceptible to threaten European forests.

Estimation des valeurs individuelles, comment faire en cas de sélection participative d'arbres forestiers. Impact de l’anthropisation et des changements climatiques sur les arbres forestiers : du fondamental à l’appliqué, un dialogue entre science et société

Melina (Gmelina arborea Roxb.) is a forest species with fast growing, tall trees. Melina propagation is based on cuttings isolated from juvenile seedlings. The present research focused on micropropagation of melina plants, grown from cuttings isolated from mature trees. Explants were surface disinfected with NaOCl (0.5%) and established on semisolid MS with (in mg L-1) myo-inositol (100), sucrose (30.000) and TC-agar (7.000). The effect of BAP (0; 0.44; 1.33 and 2.22μM) on shoot proliferation, AIB (0, 0.49, 1.48 and 2.46μM) on in vitro rooting and substrate (sand and peat) on ex vitro survival were evaluated. Treatments were distributed with a complete randomized design, 20 replicates per treatment and 80 total experimental units were evaluated. Collected data showed that compared to control BAP increased shoot proliferation, shoot length and leaf number, while IBA induced higher root number, root length and rooting percentages. Higher survival rates were observed when plants were transferred to peat. Melina (Gmelina arborea Roxb.) es una especie forestal de gran potencial por la rapidez de crecimiento y altura de sus árboles; sin embargo, la propagación clonal para siembra de huertos forestales se basa preferencialmente en el enraizamiento de estacas provenientes de plantas jóvenes obtenidas a partir de semillas. En el presente estudio se evaluó la micropropagación de plantas de melina obtenidas de miniestacas enraizadas aisladas de árboles adultos. Los explantes fueron desinfectados con 0,5% NaOCl y establecidos en medio MS semisólido con (en mg L-1) mio-inositol (100), sacarosa (30.000) y agar (7.000). Se evaluó el efecto de BAP (0; 0,44; 1,33 y 2,22μM) sobre la multiplicación de brotes, el efecto de AIB(0; 0,49; 1,48 y 2,46μM) sobre el enraizamiento de tallos micropropagados y el del tipo de sustrato (arena y turba) sobre la adaptación ex vitro de las plantas micropropagadas. Todos los tratamientos se distribuyeron con un DCA y cada tratamiento se repitió 20 veces para un total de 80 unidades experimentales. Los resultados mostraron que el suministro de BAP en el medio incrementa significativamente la tasa de multiplicación, la longitud de brotes y el número de hojas producidas, mientras que la adición de AIB aumenta el porcentaje de enraizamiento e influye significativamente en las variables número de raíces por tallo y longitud promedio de raíz. La mayor supervivencia se observó en el sustrato turba.

Acacia (Acacia mangium Willd) is one of the most planted forest species because of the quality of its wood; however, and despite its importance is not easy to find juvenile plant material in adult trees to be used as a source for vegetative propagation. The present research had as objective to develop a micropropagation protocol for acacia from preexisting meristems. The explants consisted of stem section isolated from three months old plants maintained in under greenhouse condition sand shoots from in vitrogerminatedseeds. Surface disinfection was done with different sodium hypochlorite (NaOCl) concentrations plus antibiotics. Disinfected shoots were established in semisolid MS with different BAP concentrations (0; 0,44; 0,88 and 2,22 µM). Multiplied shoots were rooted using different NAA and IBA amounts and finally shoots with, or without, roots were transferred to ex vitro conditions to evaluate field adaptation. The data showed that 1,0% NaOCl and cefalexina (2 mg L-1) allowed the highest percentage of non-contaminated explants (67%). Explants cultured with 2,22 µM BAP produced the highest number of new shoots, while 2,69 µM ANA induced more roots per shoot. An 87% survival was observed., Acacia (Acacia mangium Willd) es una de las especies forestales más plantadas por la calidad de su madera y rápido crecimiento; sin embargo, los estudios de propagación clonal son pocos. El presente trabajo tuvo como objetivo desarrollar un protocolo de micropropagacion a partir de explantes con meristemos preexistentes. Los explantes consistieron de brotes de plantas de tres meses de edad mantenidas en invernadero. La desinfección se realizó con diferentes concentraciones de hipoclorito de sodio y antibióticos, y fueron establecidos en medio MS con diferentes concentraciones (0; 0,44; 0,88 y 2,22 µM) de BAP. Los brotes micropropagados fueron enraizados con diferentes dosis de ANA y AIB, finalmente los brotes, con o sin raíces, fueron transferidos a condiciones ex vitro para evaluar el porcentaje de supervivencia. Los datos mostraron que 1,0% NaOCl y cefalexina (2 mg L-1) permitieron obtener el mayor porcentaje de explantes libres de contaminación (67%). El mayor número promedio de brotes ocurrió con 2,22 µM de BAP y el mayor número promedio de raíces se observo al utilizar 2,69 µM de ANA. La adaptación de las plantas en condiciones ex vitro fue exitoso lográndose obtener un 87% de supervivencia.

La phyllosphère des arbres forestiers: un habitat peu exploré mais très peuplé!. Séminaire AIP Bioressources

Survie et croissance de 6 feuillues plantés dans les landes de Gascogne

This contributed volume was produced with funding from EU Research Infrastructure Action "TREEBREEDEX". Contract Number 026076; Forest tree breeding has been ongoing for more than 70 years across Europe. It has successfully generated improved varieties for the major economical forest tree species. They are part of the present European forestry landscape and largely contribute to intensive wood production and other forest activities. In this book, we describe the state-of-art of breeding for the main forest tree species. We provide a comprehensive, unique and up-to-date overview of the major scientific results and breeding achievements gathered from the many programmes scattered across Europe. The book is divided into 10 chapters, each as a monograph corresponding to a species or group of species Abies spp., (Larix spp., Picea abies, Picea sitchensis, Pinus sylvestris, Pseudotsuga menziesii, and Mediterranean pines; Acer pseudoplatanus, Fraxinus excelsior, and Prunus avium). Each of them is written by a group of experts and focuses on the distribution and economical importance of the species; motivation for breeding and breeding objectives; intraspecific genetic variability, breeding populations and breeding strategy; forest reproductive material deployment including mass-propagation and, prospects and perspectives for joint research and breeding. The book is a unique and up-dated source of information for students, researchers and professionals interested in the genetics and domestication of forest tree species.

Métagénomique de la phyllosphère des arbres forestiers (METAPHORE)

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Nothofagus alessandrii ("ruil") is an endangered species native to the Maule Coastal Forest of central Chile. Previous studies have demonstrated that the current distribution of this species and rates of deforestation and fragmentation present a serious threat to the species. To address this threat, spatial and temporal variation in remnant "ruil" forest cover was analyzed for the period from 1991 to 2008. Using aerial photography and geomatic tools, the state of "ruil" forests cover in 1991 was compared to the "ruil" forests cover in 2008 and with this information, the potential distribution area of this species was calculated. The results demonstrate that the current area of "ruil" forest is approximately 314 ha, with a net loss of 42 ha (12% of the forested area) over the 17-year study period. The annual deforestation rate for "ruil" during this period was 0.74%, a value that is significantly lower than that reported just two decades ago. Taken together with the fact that the majority of "ruil" forests belong to large private companies, with an additional 15% protected by the Chilean government, the conservation status of "ruil" forest has become less critical, at least in the short term. In addition, the habitat model from this study showed that there is a large area of 9,841 ha within which "ruil" forests could be greatly expanded through active forest restoration. Nothofagus alessandrii Espinosa ("ruil"), es una de las especies características del Bosque Maulino costero de la zona central de Chile, que se encuentra en peligro de extinción. Se ha descrito que su patrón de distribución, deforestación y fragmentación la podrían llevar a la desaparición. Por ello, se realizó un análisis comparativo de la variación temporal y espacial de estos bosques entre los años 1991 y 2008. Por medio de fotografías aéreas y herramientas de geomática, se determinó el área boscosa en esos dos periodos y, a partir de esa información, se estimó la superficie potencial de la especie. Los resultados muestran que el área actual cubierta por bosques de "ruil" es de ~314 ha, lo que ha significado una disminución de 42 ha en 17 años (12% de la superficie boscosa). La tasa de deforestación anual en este periodo fue de 0,74%, significativamente menor a la reportada hace dos décadas, lo que junto a la concentración de los bosques de mayor superficie en grandes empresas privadas y al 15% protegido por el Estado de Chile, permiten visualizar, al menos en el corto plazo, una situación menos crítica para la conservación de la especie. Existe una superficie potencial, de acuerdo al modelo desarrollado, de 9.841 ha con las que se podría incrementar el recurso a través de la restauración forestal.

Santelices, R., F. Drake, C. Mena, R. Ordenes, and R.M. Navarro-Cerrillo. 2012. Current and potential distribution areas for Nothofagus alessandrii, an endangered tree species from central Chile. Cien. Inv. Agr. 39(3): 521-531. Nothofagus alessandrii ("ruil") is an endangered species native to the Maule Coastal Forest of central Chile. Previous studies have demonstrated that the current distribution of this species and rates of deforestation and fragmentation present a serious threat to the species. To address this threat, spatial and temporal variation in remnant "ruil" forest cover was analyzed for the period from 1991 to 2008. Using aerial photography and geomatic tools, the state of "ruil" forests cover in 1991 was compared to the "ruil" forests cover in 2008 and with this information, the potential distribution area of this species was calculated. The results demonstrate that the current area of "ruil" forest is approximately 314 ha, with a net loss of 42 ha (12% of the forested area) over the 17-year study period. The annual deforestation rate for "ruil" during this period was 0.74%, a value that is significantly lower than that reported just two decades ago. Taken together with the fact that the majority of "ruil" forests belong to large private companies, with an additional 15% protected by the Chilean government, the conservation status of "ruil" forest has become less critical, at least in the short term. In addition, the habitat model from this study showed that there is a large area of 9,841 ha within which "ruil" forests could be greatly expanded through active forest restoration.

Nothofagus alessandrii ("ruil") is an endangered species native to the Maule Coastal Forest of central Chile. Previous studies have demonstrated that the current distribution of this species and rates of deforestation and fragmentation present a serious threat to the species. To address this threat, spatial and temporal variation in remnant "ruil" forest cover was analyzed for the period from 1991 to 2008. Using aerial photography and geomatic tools, the state of "ruil" forests cover in 1991 was compared to the "ruil" forests cover in 2008 and with this information, the potential distribution area of this species was calculated. The results demonstrate that the current area of "ruil" forest is approximately 314 ha, with a net loss of 42 ha (12% of the forested area) over the 17-year study period. The annual deforestation rate for "ruil" during this period was 0.74%, a value that is significantly lower than that reported just two decades ago. Taken together with the fact that the majority of "ruil" forests belong to large private companies, with an additional 15% protected by the Chilean government, the conservation status of "ruil" forest has become less critical, at least in the short term. In addition, the habitat model from this study showed that there is a large area of 9,841 ha within which "ruil" forests could be greatly expanded through active forest restoration.

Neotropical rainforests exhibit high levels of endemism and diversity. Although the evolutionary genetics of plant diversification has garnered increased interest, phylogeographic studies of widely distributed species remain scarce. Here we describe chloroplast and nuclear variation patterns in Schizolobium parahyba (Fabaceae), a widespread tree in Neotropical rainforests that harbor two varieties with a disjunct distribution. Chloroplast and nuclear sequence analyses yielded 21 and 4 haplotypes, respectively. Two genetic diversity centers that correlate with the two known varieties were identified: the Southeastern Atlantic forest and the Amazonian basin. In contrast, the populations from southern and northeastern Atlantic forests and Andean-Central American forests exhibited low levels of genetic diversity and divergent haplotypes, likely related to historical processes that impact the flora and fauna in these regions, such as a founder's effect after dispersion and demographic expansion. Phylogeographic and demographic patterns suggest that episodes of genetic isolation and dispersal events have shaped the evolutionary history for this species, and different patterns have guided the evolution of S. parahyba. Moreover, the results of this study suggest that the dry corridor formed by Cerrado and Caatinga ecoregions and the Andean uplift acted as barriers to this species' gene flow, a picture that may be generalized to most of the plant biodiversity tropical woodlands and forests. These results also reinforce the importance of evaluating multiple genetic markers for a more comprehensive understanding of population structure and history. Our results provide insight into the conservation efforts and ongoing work on the genetics of population divergence and speciation in these Neotropical rainforests. (C) 2012 Elsevier Inc. All rights reserved.

Forest trees are the dominant species in many parts of the world and predicting how they might respond to climate change is a vital global concern. Trees are capable of long-distance gene flow, which can promote adaptive evolution in novel environments by increasing genetic variation for fitness. It is unclear, however, if this can compensate for maladaptive effects of gene flow and for the long-generation times of trees. We critically review data on the extent of long-distance gene flow and summarise theory that allows us to predict evolutionary responses of trees to climate change. Estimates of long-distance gene flow based both on direct observations and on genetic methods provide evidence that genes can move over spatial scales larger than habitat shifts predicted under climate change within one generation. Both theoretical and empirical data suggest that the positive effects of gene flow on adaptation may dominate in many instances. The balance of positive to negative consequences of gene flow may, however, differ for leading edge, core and rear sections of forest distributions. We propose future experimental and theoretical research that would better integrate dispersal biology with evolutionary quantitative genetics and improve predictions of tree responses to climate change. © 2012 Blackwell Publishing Ltd/CNRS.

Roots of young Norway spruce seedlings were incubated under hydroculture conditions in a synthetic nutrient medium containing either 3H-isopentenyladenosine, isopentenyladenosine or zeatin riboside. When feeding with 3H-isopentenyladenosine a new radiaolabelled metabolite was found in the feeding solution as well as in root extracts. Isopentenyladenosine and zeatin riboside were metabolised and for both compounds an unknown metabolite was detected in the feeding solution. The metabolites were purified by solid phase extraction, HPLC and partially characterised. A major characteristic of the metabolites is their reactivity in the presence of NH4OH, which results in the formation of the cytokinin bases isopentenyladenine or zeatin, respectively. UV-spectra and the chemical characteristics indicate that the new metabolites are closely related. The GC-MS analysis revealed, that the metabolites are true derivatives of isopentenyladenine and zeatin. The biogenesis of the new metabolites is discussed with regard to plant microbial interactions.

The agrobacterial isopentenyltransferase (ipt) gene, under the control of its native promoter, was transferred to poplar (Populus tremula x P. alba) by an Agrobacterium co-cultivation method. The ipt-transformed stem explants developed calli that regenerated many buds in the absence of exogenous cytokinins. Microcuttings of the ipt transformants exhibited frequently branching shoots with short internodes that were unable to root. In this material, the concentrations of zeatin, zeatin riboside and isopentenyladenosine, determined by an indirect enzyme-linked immunosorbent assay (ELISA), were 4.8-. 17.1- and 14.6-fold higher, respectively, than in non-transformed shoots. Results are discussed with regard to cytokinin metabolism.

International audience; Forest declines are usually complex multifactorial phenomena that involve interactions between different factors. While interactions between insects and pathogens have been shown to often be of primary importance, the possible interaction between different types of pathogens has not yet been investigated. Through artificial inoculation on oak seedlings, we studied the interaction between two root rot basidiomycetes, Collybia fusipes and Armillaria mellea and two Phytophthora species, P. cinnamomi and P. cambivora. These pathogens were inoculated onto young Quercus robur saplings in greenhouse conditions, either alone or combining a root rot basidiomycete with a Phytophthora species. Three out of the four Phytophthora * root rot basidiomycete combinations tested resulted in damages to oak host significantly larger than the sum of the damages induced by the pathogens on their own. This positive interaction could be significant in the oak decline syndrome.

Every year approximately half a million hectares of land are burned by wildfires in southern Europe, causing large ecological and socio-economic impacts. Climate and land use changes in the last decades have increased fire risk and danger. In this paper we review the available scientific knowledge on the relationships between landscape and wildfires in the Mediterranean region, with a focus on its application for defining landscape management guidelines and policies that could be adopted in order to promote landscapes with lower fire hazard. The main findings are that (1) socio-economic drivers have favoured land cover changes contributing to increasing fire hazard in the last decades, (2) large wildfires are becoming more frequent, (3) increased fire frequency is promoting homogeneous landscapes covered by fire-prone shrublands; (4) landscape planning to reduce fuel loads may be successful only if fire weather conditions are not extreme. The challenges to address these problems and the policy and landscape management responses that should be adopted are discussed, along with major knowledge gaps. L'articolo è disponibile sul sito dell'editore www.elsevier.com

Development of clonal propagation methods, such as somatic embryogenesis, has potentially numerous applications and advantages over conventional rooted cuttings (Klimaszewska et al. 2007). The speed at which a new material can be produced, the high potential of amplification make somatic embryogenesis a powerful and flexible tool for the release of improved varieties. Indeed, this efficient method of plant regeneration constitutes a tool for research (study of gene function) and for species improvement (production of a large number of genetically improved plants). Somatic embryogenesis can contribute to increase selection efficiency and facilitate deployment of improved varieties. Somatic embryogenesis has in many instances become the method of choice for clonal propagation of conifers (Sutton 2002). Its deployment is now achieved in Canada (CellFor, JD Irving), United States (Arborgen, Weyerhaeuser) where millions of emblings are routinely produced (Picea sp., Pinus sp., Pseudotsuga menziesii). By comparison, it was interesting to make the point of advances made in Europe. Therefore, in the frame of the European project Treebreedex (http://treebreedex.eu), a review has been made on somatic embryogenesis in both Angiosperm and Gymnosperms forest tree species, results that will be presented today.

International audience; Plant population genetic surveys are starting to take full advantage of technological advances in genotyping methods and of methodological advances in demographic inference. In this issue of Molecular Ecology, Keller et al. (2010) illustrate this trend with a particularly convincing study of rangewide genetic variation in a North American poplar, using both SNP and sequence data. They first investigate population genetic structure by estimating the most likely number of genetic clusters using a more formal approach than most other studies to date. They proceed by estimating gene flow among the inferred populations and by testing predictions on the distribution of low frequency alleles derived from recent work on range expansions.

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Les changements climatiques de ces dernières années poussent les gestionnaires forestiers à étudier leurs effets sur les peuplements forestiers. Entre autre, cette interrogation se pose pour les sapinières des zones de montagnes méditerranéennes où des dépérissements ont été notés depuis les années 2000. Le principal objectif de cette étude est de détecter et de cartographier les dépérissements des Sapins pectinés constatés sur le versant Nord du massif du Mont-Ventoux (84), situé dans le Sud de la France. Pour ce faire, la télédétection à haute résolution spatiale est un outil bien approprié puisque qu’elle permet d’observer la répartition spatiale de la végétation sur des périodes relativement longues. Dans cette étude, nous avons exploité une série temporelle d’images SPOT échelonnées sur une période de vingt ans. Les différentes images ont été corrigées en vue d’obtenir un signal spectral du couvert végétal cohérent au cours du temps. Ces corrections sont principalement de deux types : géométriques et atmosphériques. De ce signal, le calcul des indices de végétation (NDVI et RVI) sur l’ensemble des images ont permis de suivre l’évolution de l’état sanitaire des zones sapinières. Les dépérissements constatés dans ces zones par les forestiers sont bien détectés avec les images. En revanche, la méthode développée dans cette étude reste sensible aux différences de précipitations interannuelles qui modifient le comportement du sous-bois et affectent le signal de réflectance, Recent Climate changes led forest managers to examine their effects on forest stands. Among others, this question arises for the Mediterranean and mountainous fir forests where decline is recorded since the 2000s. The main objective of this study is to detect and to map silver fir decline recorded on the northern slopes of Mont-Ventoux (84), located in the South of France. The high spatial resolution remote sensing appears as an adequate tool to spatially monitor forests over long temporal periods. This study is performed by processing a time series of SPOT images over a period of twenty years. Images were geometrically and atmospherically corrected to obtain a consistent spectral output of the canopy over the time. Vegetation indices (NDVI and RVI) were then computed over the period and allowed monitoring the health status of fir areas. Thus, it seems possible to detect the fir decline observed in these areas. However, these results seem to be sensitive to inter-annual rainfall differences that may affect the understory conditions, and therefore, the reflectance signal

International audience; Our aim is to present why the hypothesis, that Ophiostomatoid fungi play an important role in the establishment of most bark beetle species on living conifers, is valuable.* After summarizing knowledge about the relationships of bark beetles with conifers and fungi, we conclude that controversy results from misinterpretations when using fungal pathogenicity to demonstrate the role of Ophiostomatoid fungi in beetle establishment on host trees.* We demonstrate that fungal pathogenicity is not the right parameter to appreciate the role of fungus in beetle establishment on host trees. We argue that artificial low density inoculations that allow the appreciation of fungus ability to stimulate tree defenses and thus to help beetles in overcoming tree resistance must be used in complement to mass inoculations. In both cases, results must be expressed in terms of tree defense stimulation rather than in terms of tree killing. (i)Fungal species stimulating tree defenses are generally not those that grow the best in the sapwood.(ii)We argue that beetle development in the phloem, fungal invasion of the sapwood and phloem, and tree death, occur after tree defenses are exhausted, and that any fungus present in the beetle gallery could thus potentially invade the sapwood after defense exhaustion.* We conclude that stimulation of the tree defense reactions in both the phloem and the superficial sapwood is a real benefit brought by fungi to the beetles during the first phase of establishment (overcoming tree resistance).* Considering the origin of the bark beetle fungus associations attacking living trees and their general functioning based on stimulation of tree defenses, we develop three hypotheses: (i)any beetle species would be helped in its establishment in a given tree species by developing an association, even loosely, with a fungus species belonging to the Ophiostomatoid flora of that tree species;(ii) the necessity of a considerably low level of tree resistance for fungus extension into the tree is the selection pressure that has led fungi to develop their intrinsic ability to stimulate tree defenses, through their ability to grow into the phloem. This association can be completed by antagonistic fungal species controlling extension of the previous fungal species in the tree tissues; (iii) Beetle species using the strategy of overcoming tree resistance are associated with a fungal complex, of which species could assume three roles regarding relationships between beetles and trees: 1- to stimulate tree defenses in the phloem and superficial sapwood, 2- to grow into the sapwood after tree resistance is overcome, and 3- to control phloem extension of the first other two categories. Bringing nutrients to the beetle progeny can be a fourth role.* We propose that bark beetle - Ophiostomatoid associations can be categorized, based on associations' frequency and complexity while taking into account beetle aggressiveness. We show that a close correspondence exists between beetles' aggressiveness and the ability of their main associated fungal species to stimulate the defenses of their host tree.* We conclude with suggesting that most sapwood invading fungi might be "cheaters" which have taken advantage of the efficiency of the relationship between beetles and fungi that stimulate tree defenses.; Notre objectif est de présenter les raisons de la validité de l'hypothèse selon laquelle les champignons jouent un rôle important dans l'installation de la plupart des espèces de Scolytes sur conifères vivants.* Après avoir résumé les connaissances sur les relations des Scolytes avec les conifères et les champignons, nous concluons que la controverse résulte d'interprétations erronées lorsque l'on utilise le pouvoir pathogène des champignons pour démontrer le rôle des Ophiostomatoïdes dans l'installation des insectes sur les arbres hôtes.* Nous démontrons que le pouvoir pathogène n'est pas le paramètre correct pour apprécier le rôle du champignon dans l'installation des Scolytes sur les arbres hôtes. Nous soutenons que des inoculations artificielles à faible densité, qui permettent d'apprécier la capacité du champignon à stimuler les défenses de l'arbre et à ainsi aider le Scolyte à surmonter la résistance de celui-ci, doivent être utilisées en complément des inoculations massives. Dans les deux cas, les résultats doivent être exprimés en termes de stimulation des défenses de l'arbre plutôt qu'en termes de mortalité de l'arbre. (i) les espèces de champignons qui stimulent les défenses de l'arbre ne sont généralement pas celles qui présentent la meilleure croissance dans l'aubier. (ii) nous soutenons que le développement de l'insecte dans le phloème, l'invasion de l'aubier et du phloème par le champignon, et la mort de l'arbre, interviennent après épuisement des défenses de l'arbre, et que tout champignon présent dans les galeries de l'insecte pourrait donc potentiellement envahir l'aubier après épuisement de ces défenses. * Nous concluons que la stimulation des réactions de défense de l'arbre à la fois dans le phloème et l'aubier superficiel représente un bénéfice réel apporté par les champignons aux Scolytes pendant la première phase de leur installation (surmonter la résistance de l'arbre).* En ce qui concerne l'origine des associations Scolytes - champignons attaquant les arbres vivants et considérant leur fonctionnement général basé sur une stimulation des défenses de l'arbre, nous développons trois hypothèses: (i) toute espèce de Scolyte serait aidée dans son installation sur une espèce d'arbre donnée en développant une association, même lâche, avec une espèce de champignon appartenant à la flore Ophiostomatoïde de cette espèce d'arbre; (ii) la nécessité d'un très faible niveau de résistance de l'arbre pour autoriser l'extension fongique dans le végétal est la pression de sélection qui a conduit les champignons à développer leur capacité intrinsèque de stimulation des défenses de l'arbre, à travers leur capacité à croître dans le phloème. Cette association peut être complétée par des espèces fongiques antagonistes contrôlant l'extension des espèces précédentes dans les tissus de l'arbre; (iii) les espèces de Scolytes utilisant la stratégie de surmonter la résistance de l'arbre sont associées à un complexe fongique dont les espèces assurent trois fonctions eu égard aux relations entre les Scolytes et les arbres: 1- stimuler les défenses de l'arbre dans le phloème et l'aubier superficiel, 2- croître dans l'aubier après que la résistance de l'arbre ait été vaincue, and 3- contrôler l'extension des deux catégories précédentes dans le phloème. L'apport de nutriments à la progéniture du Scolyte peut représenter une quatrième fonction. * Nous proposons que les associations Scolytes - Ophiostomatoïdes puissent être classées, en se basant sur la fréquence et la complexité de l'association et en prenant en compte l'agressivité de l'insecte. Nous montrons qu'il existe une étroite correspondance entre l'agressivité des insectes et la capacité de leur principale espèce fongique associée à stimuler les défenses de l'arbre hôte.* Nous concluons en suggérant que la plupart des espèces de champignons envahissant l'aubier pourraient être des "tricheurs" qui ont profité de l'efficacité des relations entre les Scolytes et les espèces fongiques stimulatrices des défenses de l'arbre.

International audience; Our aim is to present why the hypothesis, that Ophiostomatoid fungi play an important role in the establishment of most bark beetle species on living conifers, is valuable.* After summarizing knowledge about the relationships of bark beetles with conifers and fungi, we conclude that controversy results from misinterpretations when using fungal pathogenicity to demonstrate the role of Ophiostomatoid fungi in beetle establishment on host trees.* We demonstrate that fungal pathogenicity is not the right parameter to appreciate the role of fungus in beetle establishment on host trees. We argue that artificial low density inoculations that allow the appreciation of fungus ability to stimulate tree defenses and thus to help beetles in overcoming tree resistance must be used in complement to mass inoculations. In both cases, results must be expressed in terms of tree defense stimulation rather than in terms of tree killing. (i)Fungal species stimulating tree defenses are generally not those that grow the best in the sapwood.(ii)We argue that beetle development in the phloem, fungal invasion of the sapwood and phloem, and tree death, occur after tree defenses are exhausted, and that any fungus present in the beetle gallery could thus potentially invade the sapwood after defense exhaustion.* We conclude that stimulation of the tree defense reactions in both the phloem and the superficial sapwood is a real benefit brought by fungi to the beetles during the first phase of establishment (overcoming tree resistance).* Considering the origin of the bark beetle fungus associations attacking living trees and their general functioning based on stimulation of tree defenses, we develop three hypotheses: (i)any beetle species would be helped in its establishment in a given tree species by developing an association, even loosely, with a fungus species belonging to the Ophiostomatoid flora of that tree species;(ii) the necessity of a considerably low level of tree resistance for fungus extension into the tree is the selection pressure that has led fungi to develop their intrinsic ability to stimulate tree defenses, through their ability to grow into the phloem. This association can be completed by antagonistic fungal species controlling extension of the previous fungal species in the tree tissues; (iii) Beetle species using the strategy of overcoming tree resistance are associated with a fungal complex, of which species could assume three roles regarding relationships between beetles and trees: 1- to stimulate tree defenses in the phloem and superficial sapwood, 2- to grow into the sapwood after tree resistance is overcome, and 3- to control phloem extension of the first other two categories. Bringing nutrients to the beetle progeny can be a fourth role.* We propose that bark beetle - Ophiostomatoid associations can be categorized, based on associations' frequency and complexity while taking into account beetle aggressiveness. We show that a close correspondence exists between beetles' aggressiveness and the ability of their main associated fungal species to stimulate the defenses of their host tree.* We conclude with suggesting that most sapwood invading fungi might be "cheaters" which have taken advantage of the efficiency of the relationship between beetles and fungi that stimulate tree defenses.; Notre objectif est de présenter les raisons de la validité de l'hypothèse selon laquelle les champignons jouent un rôle important dans l'installation de la plupart des espèces de Scolytes sur conifères vivants.* Après avoir résumé les connaissances sur les relations des Scolytes avec les conifères et les champignons, nous concluons que la controverse résulte d'interprétations erronées lorsque l'on utilise le pouvoir pathogène des champignons pour démontrer le rôle des Ophiostomatoïdes dans l'installation des insectes sur les arbres hôtes.* Nous démontrons que le pouvoir pathogène n'est pas le paramètre correct pour apprécier le rôle du champignon dans l'installation des Scolytes sur les arbres hôtes. Nous soutenons que des inoculations artificielles à faible densité, qui permettent d'apprécier la capacité du champignon à stimuler les défenses de l'arbre et à ainsi aider le Scolyte à surmonter la résistance de celui-ci, doivent être utilisées en complément des inoculations massives. Dans les deux cas, les résultats doivent être exprimés en termes de stimulation des défenses de l'arbre plutôt qu'en termes de mortalité de l'arbre. (i) les espèces de champignons qui stimulent les défenses de l'arbre ne sont généralement pas celles qui présentent la meilleure croissance dans l'aubier. (ii) nous soutenons que le développement de l'insecte dans le phloème, l'invasion de l'aubier et du phloème par le champignon, et la mort de l'arbre, interviennent après épuisement des défenses de l'arbre, et que tout champignon présent dans les galeries de l'insecte pourrait donc potentiellement envahir l'aubier après épuisement de ces défenses. * Nous concluons que la stimulation des réactions de défense de l'arbre à la fois dans le phloème et l'aubier superficiel représente un bénéfice réel apporté par les champignons aux Scolytes pendant la première phase de leur installation (surmonter la résistance de l'arbre).* En ce qui concerne l'origine des associations Scolytes - champignons attaquant les arbres vivants et considérant leur fonctionnement général basé sur une stimulation des défenses de l'arbre, nous développons trois hypothèses: (i) toute espèce de Scolyte serait aidée dans son installation sur une espèce d'arbre donnée en développant une association, même lâche, avec une espèce de champignon appartenant à la flore Ophiostomatoïde de cette espèce d'arbre; (ii) la nécessité d'un très faible niveau de résistance de l'arbre pour autoriser l'extension fongique dans le végétal est la pression de sélection qui a conduit les champignons à développer leur capacité intrinsèque de stimulation des défenses de l'arbre, à travers leur capacité à croître dans le phloème. Cette association peut être complétée par des espèces fongiques antagonistes contrôlant l'extension des espèces précédentes dans les tissus de l'arbre; (iii) les espèces de Scolytes utilisant la stratégie de surmonter la résistance de l'arbre sont associées à un complexe fongique dont les espèces assurent trois fonctions eu égard aux relations entre les Scolytes et les arbres: 1- stimuler les défenses de l'arbre dans le phloème et l'aubier superficiel, 2- croître dans l'aubier après que la résistance de l'arbre ait été vaincue, and 3- contrôler l'extension des deux catégories précédentes dans le phloème. L'apport de nutriments à la progéniture du Scolyte peut représenter une quatrième fonction. * Nous proposons que les associations Scolytes - Ophiostomatoïdes puissent être classées, en se basant sur la fréquence et la complexité de l'association et en prenant en compte l'agressivité de l'insecte. Nous montrons qu'il existe une étroite correspondance entre l'agressivité des insectes et la capacité de leur principale espèce fongique associée à stimuler les défenses de l'arbre hôte.* Nous concluons en suggérant que la plupart des espèces de champignons envahissant l'aubier pourraient être des "tricheurs" qui ont profité de l'efficacité des relations entre les Scolytes et les espèces fongiques stimulatrices des défenses de l'arbre.

Invading Nature- Springer Series in Invasion Ecology by James A. Drake (Series Editor) ; International audience

Les données issues de la télédétection couplées à des approches de type système d’information géographique sont d’un grand intérêt potentiel pour l’aménagement forestier. Le but de cette recherche est dans un premier temps de fournir une cartographie utilisable des espèces forestières dominantes à l'échelle du pixel, en utilisant des méthodes éprouvées de la télédétection. Le site d’étude choisi est le versant sud du Mont Ventoux, une montagne méditerranéenne présentant une forte biodiversité forestière. Les travaux relatés dans la première partie ont permis de réaliser des cartographies discriminantes des espèces forestières à partir des données satellitaires (Spot 5) par classification supervisée et non supervisée, en lien avec des relevés terrains. La pertinence de ces méthodes pour la cartographie de la couverture forestière est évaluée et discutée, l'objectif étant d’identifier les conditions optimales en fonction de la résolution spatiale et de la bande spectrale pour la discrimination des espèces forestières majeures du Mont Ventoux. Ce travail nous a ensuite amenés à proposer une méthode originale de mesure de la variabilité de la biodiversité à l'aide de 4 indices classiques : indices de Shannon, de Simpson, de Richesse et de Dominance. L'approche a été appliquée en utilisant deux descripteurs de la biodiversité : l’indice de végétation normalisé (NDVI) et la diversité en espèces forestières. Cette méthode inédite permet, grâce au recours à différentes images de résolutions spatiales imbriquées et à un processus systématique d'agrégation, d’extraire la part de biodiversité (alpha et bêta) due à la structure spatiale, en éliminant l'effet du support spatial, composante déterminante du Modifiable Areal Unit Problem (MAUP). Nous discutons également dans cette recherche de la capacité de notre méthode à extraire, une « échelle pertinente » de mesure de la diversité, Data resulting from the remote sensing coupled to geographical information systems (GIS) are of great potential for forest management. The aim of this research is to design a cartography of the forest species which can be usable for assessing biodiversity at a fine and accurate resolution. The studied site is the southern slope of the “Mont Ventoux”, a Mediterranean mountain presenting a large forest biodiversity. We discriminated forest species using SPOT 5 data, using supervised and non supervised classification techniques. The relevance of these methods for the cartography of the forest cover is evaluated and discussed, the objective being to identify the optimal conditions according to the spatial resolution and the spectral band for the discrimination of the major forest species of the Mont Ventoux. In a second general section, we propose an original method for measuring biodiversity. We estimated spatial biodiversity aspects using 4 indices (Shannon, Simpson, Richness, and Dominance) and two descriptors: the normalized index of vegetation (NDVI) and the forest species diversity. Using various images at different spatial resolutions, a systematic process of aggregation and an original resampling of pixels, we were able to identify the amount of 'real' biodiversity (alpha and beta) variability due to the spatial structure. This new method is probably the first step for eliminating the well-known MAUP (Modifiable Areal Unit Problem), due to the spatial support. Moreover, we discuss our capacity to point out a “pertinent scale” for diversity measurement, concept which is discussed and highlighted according to a few different spatial support shapes and the biodiversity indices we processed

We investigated the inter-individual variation of phenotypic plasticity and its evolution across three generations within an expanding forest. Plasticity was assessed in situ from dendrochronological data as the response of radial growth to summer rainfall. A linear mixed model was used to account for spatial effects (environment and stand structure), temporal factors (stand dynamics) and the variation with age. Beyond these effects, our results reveal a significant inter-individual variance of growth and plasticity within each generation. We also show that the mean values and variances of growth and plasticity changed significantly across generations, with different patterns for both traits. The possible environmental and genetic drivers of these changes are discussed. Contrasting with the trade-off between stress tolerance and plasticity generally observed among populations, we detected a positive covariance at the individual level, which does not support the cost of plasticity hypothesis in this case.

International audience; Oak powdery mildew severity (Erysiphe alphitoides) is usually mild in Europe because epidemics start late in spring, at the end of the first oak growth unit maturation. However, the disease can occasionally be very severe when strong infection occurs early during the development of the first growth unit, suggesting that host-pathogen synchrony in spring could be a critical factor in disease severity.* We studied the timing of ascospore production in a given environment for four E. alphitoides populations sampled from SW France to the Czech Republic to determine whether this trait shows variation within Europe.* Timing of ascospore production was clearly influenced by environmental factors as chasmothecia from a single origin showed very different dates of optimal ascospore production when transferred for overwintering in locations with different climate. In common garden experiments, no differences were observed between populations for the date of optimal ascospore production.* Results suggest little genetic differentiation for timing of ascospore production for E. alphitoides populations across Europe and therefore a lack of local adaptation to their host phenology. Availability in ascospore inoculum is limited during host budburst, explaining the low infection usually observed on the first oak growth unit.; L'oïdium du chêne (Erysiphe alphitoides) est généralement peu sévère en Europe, la maladie se développant tard au printemps, après le débourrement des chênes. E. alphitoides peut toutefois être sévère quand de fortes infections se produisent tôt durant le débourrement, suggérant que la synchronisation entre hôte et pathogène pourrait être un facteur déterminant la sévérité des épidémies.* Nous avons caractérisé la dynamique de production d'ascospores dans un environnement donné pour quatre populations d'E. alphitoides échantillonnées du sud-ouest de la France à la République Tchèque pour tester si ce trait est variable en Europe.* Des chasmothèces d'une même origine présentent des dates d'optima de production d'ascospores très différentes quand elles sont transférées durant l'hiver dans des zones à climats différents montrant que ce trait est sous dépendance de l'environnement. Par contre, les quatre populations ont la même date d'optimum de production d'ascospores quand elles sont placées dans un même environnement.* Les résultats suggèrent que les populations d'E. alphitoides européennes ne sont pas différentiées génétiquement pour le timing de production d'ascospores et donc qu'elles ne sont pas localement adaptées à la phénologie de leur hôte. L'inoculum ascospores est très peu présent durant le débourrement, expliquant en partie l'absence d'infection sur la première unité de croissance des chênes.

Invading Nature- Springer Series in Invasion Ecology by James A. Drake (Series Editor) ; International audience

International audience

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Format du poster : DiaporamaFormat du poster : Diaporama; absent