Séminaire IGN/AgroParisTech/LabEx ARBRE

Séminaire IGN/AgroParisTech/LabEx ARBRE
Ressources forestières et halieutiques : dynamique, modélisation, et appui aux politiques publiques dans un contexte incertain et contraint

14 octobre 2021 à 9h30

Salle de conférence

Centre INRAE-Champenoux

Ce séminaire scientifique est organisé par l’IGN et AgroParisTech dans le cadre de la soutenance de thèse de Timothée Audinot : Développement d’un modèle de dynamique forestière à grande échelle pour simuler les forêts françaises dans un contexte non-stationnaire. Thèse de doctorat Université de Lorraine, école doctorale SiReNa, Direction : J-D Bontemps (IGN), H Wernsdörfer (AgroParisTech).

Inscription et passe sanitaire requis

Contexte & Programme

 

 

 

 

 

 

 

 

Soutenance HDR

Laure VIEUBLE GONOD soutiendra son HDR intitulée : “Effets des propriétés indigènes du sol et des activités anthropiques sur les microorganismes du sol et leurs activités en contexte agricole” le vendredi 12 mars à partir de 9h devant le jury composé de : Dominique PATUREAU (rapportrice), Sylvie RECOUS (rapportrice), Lionel ALLETTO (rapporteur), Claire CHENU (examinatrice) et Fabrice MARTIN LAURENT (examinateur)

Elle se déroulera complètement en distanciel et sera accessible avec le lien suivant :
https://eu.bbcollab.com/guest/cac0251ff3254c46a14f4c759bb65074

Vous trouverez ci-dessous un résumé des travaux qui seront présentés :

Les organismes du sol et en particulier, les microorganismes du sol, jouent un rôle clef dans le fonctionnement des sols et sont impliqués dans de nombreux services écosystémiques. La biodiversité des sols a besoin d’être davantage onnue afin que l’on puisse mieux la diagnostiquer et la piloter dans le but de restaurer, maintenir et améliorer les services rendus par les sols. Les recherches développées jusqu’à aujourd’hui ont donc consisté à mieux comprendre le fonctionnement microbiologique des sols (et notamment la biodégradation) dans un contexte agricole. Le fonctionnement microbiologique des sols est contrôlé par les propriétés indigènes du sol mais peut également être impacté par les activités anthropiques et notamment les pratiques agricoles. Plus spécifiquement, mes activités de recherches, qui se déclinent à différentes échelles spatiales (du µm à la parcelle) ont porté sur l’impact de i) la structure du sol sur les microorganismes du sol et leurs activités et ii) des pratiques agricoles sur les microorganismes et leurs activités (biodégradation et devenir des pesticides dans les sols, recyclage des produits résiduaires en agriculture).

Pour ce faire, j’ai mis en oeuvre des approches essentiellement expérimentales mais j’ai également participé occasionnellement à des travaux de modélisation. Mes travaux sont à la fois fondamentaux et mécanistes mais également finalisés, ces derniers ayant pour objectifs d’apporter des éléments de réponses vis-à-vis de questions sociétales (polluants émergents, valorisation des déchets…). Mon projet de recherche pour les années à venir vise à approfondir les thématiques de recherche initiées tout en diversifiant les contextes (rural, périurbain, urbain) et en considérant d’autres systèmes de culture (alternatifs vs conventionnels) en lien avec des demandes sociétales et politiques fortes (besoin de nature en ville, développement de l’agroécologie, changement climatique…) et à prendre en considération les autres organismes du sol et en particulier la faune pour développer des connaissances sur les réseaux trophiques et les relations diversité-fonctions-services écosystémiques.

Mots clés : sol, bactéries, champignons, distribution spatiale, minéralisation, accessibilité, diffusion, advection, pesticides, produits résiduaires organiques

Summer School FORMON

ICP Forests / SwissForestLab / NFZ.forestnet are pleased to announce that registration is open for the 2021 Summer School FORMON “Forest Monitoring to assess Forest Functioning under Air Pollution and Climate Change” in Davos, Switzerland, 22-28 August 2021

More info at: https://www.wsl.ch/en/about-wsl/events/details/swissforestlab-summer-school-2021.html

Soutenance HdR

Cyrille Rathgeber soutiendra son habilitation à diriger des recherches (HdR) intitulée :

“Écophysiologie de la Formation du Bois : Concepts, Méthodes et Applications”

jeudi 5 septembre 2019 à partir de 14h00

Salle de conférence du Centre Inra Grand Est-Nancy


Analyzing the growing stock expansion in French metropolitan forests

Ph.D. defense: Anaïs Denardou-Tisserand

“Changements du stock de bois sur pied des forêts françaises – Description, analyse et simulation sur des horizons temporels pluri-décennal (1975 – 2015) et séculaire à partir des données de l’inventaire forestier national et de statistiques anciennes”,

Friday 8 February 2019 at 9.00 am at Amphi Cuénot (Aquarium), Nancy.

Context. After centuries of decrease, the forest area of most developed countries increase, a phenomenon termed “forest transition”. While current increase in growing stock (GS) is greater than that in area, it remains far less studied. These changes are linked to major current issues. It is essential to assess these changes, to decipher their underlying causes, and to quantify them over the longer term in order to locate current forest resources on a broad trajectory and to anticipate their future dynamics. This thesis is dedicated to French metropolitan forests, which exhibit the most intensive changes in the growing stock in Europe, and relies on data from the French NFI program.

Objectives.

(1) Analyse forest areal, GS and GS density (GSD) changes and their spatio-temporal variations over 40 years (1975-2015). They were related to factors hypothesized to feature forest changes (geographical contexts, ownership and species composition). We screened for changes in the rate of expansion. The relationships between GS changes and some forest attributes (initial GS and GSD, recent forest area increase) were investigated.

(2) Uncover the processes of GS changes and to split the GS expansion magnitude across dynamically-homogeneous forest ensembles. The study was based on GS flux estimation (growth, ingrowth, mortality and harvest).

(3) Locate the actual GS expansion in a secular perspective. This analysis consisted in reconstructing the GS chronology since 1850. Levels of GS in 1892, 1908 and 1929 (associated to area of ancient statistics) were estimated using a conditional imputation approach for GSD estimation. Then, a holistic growing stock densification model was implemented to inquire the conditions required on densification patterns and magnitude to simulate the reconstituted GS chronology.

Results.

(1) Over 40 years, GS increases were three times faster than the areal ones, underlining the intensity of forest densification. No sign of saturation was found. Private forests, and mainly broadleaved ones, presented the greatest GS and GSD increases, suggesting the essential role of natural expansion and agricultural land abandonment. Regression models revealed the positive effect of initial GS and of recent areal increases on GS expansion.

(2) The analysis of GS expansion processes evidenced the low level of harvests in comparison to forest growth, and the contribution of recent forests to wood resource development. It led to identify four synthetic forest ensembles contributing to the expansion and of distinct dynamics, mainly composed of private forests.

(3) GS suggested a very low mean GSD at the beginning of the period (25 m3/ha) and a GS increase by almost +300% between 1892 and 2010, underlying the importance of this expansion. A convex growth model was required to simulate historical forest densification, attesting of a significant inertia in wood resource reconstitution after the forest transition, interpreted based on a gradual decrease in harvest rates for which indices were collected, or to a gradual recovery of site fertility. The analysis also suggested a distinct kinetics for GS densification in plantation forests.

Conclusions. These researches reveal the magnitude of GS expansion and the importance of its analysis across forest contexts. This ancient expansion does not present any current sign of saturation and constitute a persistent carbon sink which should not decrease in the next decades assuming similar contextual conditions. According to the process analysis of GS expansion, a significant fraction of the GS increases does not constitute readily available additional wood resources. Thus, future harvest intensification policies must be contextualized and evolving in time.

Keywords: forest expansion – forest transition – forest area – growing stock – volume – basal area – forest composition – forest management – land-use abandonment – plantations – harvest – national forest inventory

Workshop BENCHAFOR

On October 2nd & 3rd, scientists from the ONF, INRA and DSF will discuss the current knowledge on the biology and ecology of cockchafers to explore novel options to limit the insect outbreaks and their detrimental impact on forest regenerations.

The common and forest Cockchafer are two beetle species well known for the damages they can inflict to forest ecosystems. Whereas the adults may occasion spectacular defoliations to adult trees, the larvae also feed on the roots of young trees causing severe mortality in forest regenerations, further impacting the whole forest management process. Eastern European countries had been facing recurrent infestations since the 1960’s; in France, cockchafer populations seem to have turned from endemic to epidemic in the last 10 years, with dramatic damages reported in young forest stands of Picardie and Northern Alsace. In Germany, chemical treatments proved to be efficient in reducing populations and subsequent damages but their use is now forbidden. A wide diversity of alternatives had been investigated in Europe, mainly based on biological control methods. To date, these studies did not produce results that could be developed and ultimately applied in everyday forest management.

Forest managers now question the opportunity of modifying forest ecosystem parameters that are critical for the different phases of the cockchafer lifecycle. Such actions are likely to produce short-term efficient methods with limited environmental impacts. This project is based on a benchmarking approach of the acquired scientific knowledge of cockchafer biology and of thetechnical experiences accumulated in the European countries that have been subjected to outbreaks in the last decades. We aim at investigating whether changes in silvicultural management are able to limit cockchafer population dynamics.

Our first objective is to establish a state-of-the-art review of the knowledge concerning the environmental factors which determine cockchafer outbreaks. Then, our second objective is to propose a protocol to describe stand cover structure and ground vegetation characteristics which determine cockchafer larval density. These two objectives will initiate national and international networking on the research for solutions to cockchafer damages to forests.

Finally, the proposed project will provide a framework of hypothesis for the research of ecological solutions to prevent cockchafer outbreaks. This innovative project is likely to initiate a technical and scientific strategy for the management crisis caused by cockchafer outbreaks.