En partenariat avec le réseau MiDi, ce symposium est organisé dans le cadre de l’IUFRO (Union Internationale des Instituts de Recherches Forestières), un réseau mondial consacré à la recherche forestière.

Partenaires

INRAE Val de Loire

Unité de recherche de Zoologie forestière
Avenue de la pomme de pin
Orléans (France)

Website : http://www.val-de-loire.inrae.fr/

Université d’Orléans

Avenue du Parc floral
Orléans (France)

Website : https://www.univ-orleans.fr/

Thematic research network MiDi

Thematic research network
in Centre-Val de Loire Region
for observation and management of natural resources

Website : http://www.reseau-midi.fr/

Thematic research network EntomoCentre

EntomoCentre, Thematic research network
in Centre-Val de Loire Region
for entomology

Website : https://www.val-de-loire.inra.fr/entomocentre/

IUFRO

International Union of Forest Research Organizations

Website : https://www.iufro.org/

EPPO/OEPP

European and Mediterranean Plant Protection Organization
Organisation Européenne et Méditerranéenne pour la Protection des Plantes

Website : https://www.eppo.int/

Ministère de l’agriculture et de l’alimentation

DRAAF de la région Centre-Val de Loire, Département de la santé des forêts
Rue du faubourg Bannier
Orléans (France)

Website : http://agriculture.gouv.fr/actualite-en-sante-des-forets

Région Centre-Val de Loire

Hôtel de région
9 rue Saint-Pierre Lentin
Orléans (France)

Website : http://www.regioncentre-valdeloire.fr

« The physiological basis of tree vulnerability to heat waves »

Dr. Hervé Cochard

INRAE, UCA, UMR-PIAF, Clermont-Ferrand

December 17 at 15h (CET/Paris time)

The International Associated Laboratory FORESTIA starts in 2021 a new round of short seminars aimed at stimulating the scientific comunication among its members, as well as between them and other international laboratories. These seminars are a new opportunity for the FORESTIA scientists to present and discuss their objectives, research work and results on adaptation of forest ecosystems to global changes.

 Seminar #8 by Dr. Hervé Cochard, INRAE, UCA, UMR-PIAF, Clermont-Ferrand

 Abstract 

Tree mortality events attributable to heatwave droughts have been increasing globally for several decades and seem to affect all forest ecosystems on the planet. It is feared that this situation will worsen in the future with the increased risk of heatwave and drought predicted by climate models. Understanding the physiological basis of these die-offs can help to identify species or genotypes better adapted to future climatic conditions, but can also improve models for predicting these mortality risks. 

An edaphic drought modifies the hydric and hydraulic functions of a tree, and the more intense the drought, the greater the disturbance. Above a certain intensity, cavitation events can occur in the sap conducting tissue of the tree (xylem), which disrupts the water supply to the canopy. When the cavitation rate exceeds a critical threshold, an irreversible point of hydraulic failure of the xylem is reached, leading to desiccation and death of the branches irrigated by this tissue. The vulnerability of the xylem to cavitation thus appears to be a key physiological process in the mortality of trees exposed to drought. 

Research work in this field currently focuses on the notion of the risk of hydraulic failure incurred by a tree during a drought. This is a more complex notion that integrates not only the intrinsic vulnerability of the xylem to cavitation, but also the degree of water stress the trees are exposed to. This constraint depends on local soil and climatic conditions and the water balance of the stands, but also on the physiological capacity of the trees to control their water status in these extreme drought situations.  This capacity is determined by the water reservoirs stored in the tree, but above all by the minimum residual transpiration of the tree, which will impose its dehydration rate beyond the stomatal regulation point.  The permeability of the leaf cuticles plays a major role in this residual transpiration. It varies greatly from one species to another and, above all, it increases sharply above a critical phase transition temperature, which itself varies from one species to another.  

To assess the risk of hydraulic breakage, it is necessary to integrate all these physiological processes into a model of the tree’s hydric and hydraulic functioning. The SurEau model that we have developed fulfils this objective. It predicts the evolution of the xylem cavitation rate by taking into account the soil and climatic conditions and the physiological characteristics of the tree. The predictions of the model illustrate the key role of xylem vulnerability to cavitation and cuticle loss in the mortality process. In particular, the model predicts a high risk of cavitation when leaf temperature passes the critical phase transition threshold, which may explain the aggravating effect of heat waves. Furthermore, the model predicts a very strong increase in the risk of cavitation with global warming, even taking into account the « fertilising » effect of atmospheric CO2. The genetic variability and phenotypic plasticity of forest species seems too low to limit this risk. 

These round of FORESTIA web seminars will take place Fridays every four weeks, starting on the 4th of June 2021.

>> A new series of seminars planned for 2022 

MiDi is a interdisciplinary Research Thematic Network, focused on biodiversity and habitats and funded by the Centre-Val de Loire Region. The network aims to promote studies in multiple fields of BioGeoSciences and Human and Social Sciences in relation to global changes.

 This conference is organised in partnership with the Le Studium (Institute for Advanced Studies).

contact: valentin.cognard@univ-tours.fr

Round of FORESTIA web seminars

SEMINAR # 6

“Eulogy of fast growth… up to what costs?

A preliminary recognition before a study of trade-offs of growth heterosis

in hybrid larch.”

Luc E. Pâques

INRAE- UMR Biofora Orléans 

October 22 at 15h (CET/Paris time)

The International Associated Laboratory FORESTIA starts in 2021 a new round of short seminars aimed at stimulating the scientific comunication among its members, as well as between them and other international laboratories. These seminars are a new opportunity for the FORESTIA scientists to present and discuss their objectives, research work and results on adaptation of forest ecosystems to global changes.

 Seminar #6 by Luc E. Pâques (INRAE- UMR Biofora Orléans) ,

 Abstract

Breeding and selection for growth has been a main target worldwide since breeding programmes have been initiated in the late fifties. Significant genetic gains have been achieved in most commercial forest tree species with visible impact in the development of the wood industry. Although additional traits related to stem architecture and wood traits – and in some species pests and diseases resistance- have been progressively considered, increase of productivity remains so far, a main driver of tree improvement.

However, the many threats linked to climate changes may deeply shove the ‘wood production breeding paradigm’. Indeed, several signs from forest managers and from scientists in the literature show a shift in concerns with recommendations of planting instead slow growing species to better cope with climate changes. Their belief is that fast growing species might be less tolerant for example to drought than slow growing species.

For a breeder of one of the faster growing conifers in temperate climate (Larix sp), manipulating one of the most powerful breeding strategies (interspecific hybridisation) to enhance growth (heterosis), this evolution of priorities is clearly a source of many questionings.

As a non-expert, we intend as a first step to gather relevant information on trade-offs in plants and trees in particular, which echo with an experimentation we have been conducting since 2013. This experimentation aims to better understand how hybrid vigour in Larix x eurolepis arises, which traits (structural and functional) make the hybrid different from its parents and finally what is the cost of this over-expression of vigour.

These round of FORESTIA web seminars will take place Fridays every four weeks, starting on the 4th of June 2021.

>> Next seminar on November 19  by Susana Marcucci Poltri (INTA – Castelar).

MiDi is a interdisciplinary Research Thematic Network, focused on biodiversity and habitats and funded by the Centre-Val de Loire Region. The network aims to promote studies in multiple fields of BioGeoSciences and Human and Social Sciences in relation to global changes.

 This conference is organised in partnership with the Le Studium (Institute for Advanced Studies).

contact: valentin.cognard@univ-tours.fr

This FORESTIA seminar was originally scheduled on the 24/09. But exceptionally we had to change the date and transfer it to the 08/10. Please note that the next seminar will take place on the originally scheduled date, 22/10.

Round of FORESTIA web seminars

SEMINAR # 5

“RELATIONSHIPS BETWEEN WOOD TRAITS AND DROUGHT RESISTANCE IN EUCALYPTUS SPP: EVIDENCES AND OPEN QUESTIONS”

Dr. María Elena Fernández,

(CONICET-INTA IPADS, LIA Forestia, Tandil, Argentina)

October 8 at 15h (CET/Paris time)

The International Associated Laboratory FORESTIA starts in 2021 a new round of short seminars aimed at stimulating the scientific comunication among its members, as well as between them and other international laboratories. These seminars are a new opportunity for the FORESTIA scientists to present and discuss their objectives, research work and results on adaptation of forest ecosystems to global changes.

 Seminar #5 by María Elena Fernández, (CONICET-INTA IPADS, Tandil, Argentina). 

 Abstract

Eucalyptus is one of the main forestry genus with more than 20 million ha. planted worldwide, in addition to the native forests in Oceania, formed by more than 700 species growing in very diverse environments. Although there is broad knowledge about ecophysiological traits of eucalypts, response to silviculture (of the few planted species) and wood anatomy and technological properties related to industrial uses, we know very little about the relationships between wood anatomy and function in this genus, and their implications for drought resistance. Moreover, the wood of eucalypts is complex, with mostly solitary vessels surrounded and connected to vasicentric tracheids, fiber tracheids and parenchyma cells, all immersed in a matrix of fibers. The hydraulic functioning of this tissue cannot be understood in terms of the current knowledge of wood hydraulic function developed mostly from conifers and broadleaves with grouped vessels. We present our results related to this topic developed from commercial eucalipt plantations in Argentina and Spain; we compare them to recent (and quite opposite) results from native forests in Australia, and we delineate some of the open questions we are exploring to contribute to the adaptive management and genetic improvement of this genus in a framework of climate change.

These round of FORESTIA web seminars will take place Fridays every four weeks, starting on the 4th of June 2021.

MiDi is a interdisciplinary Research Thematic Network, focused on biodiversity and habitats and funded by the Centre-Val de Loire Region. The network aims to promote studies in multiple fields of BioGeoSciences and Human and Social Sciences in relation to global changes.

 This conference is organised in partnership with the Le Studium (Institute for Advanced Studies).