Catherine Collet

French National Institute for Agriculture, Food, and Environment (INRAE) | INRAE · Laboratoire d'Etude des Ressources Forêt - Bois (LERFoB)

Mechanical site preparation (MSP) is widely performed around the globe to enhance the success of forest plantations. However, MSP can cause severe soil disturbance whose magnitude depends on various factors such as soil characteristics, soil moisture conditions and the type of machinery. We analyzed the combined effects of machine size and soil wat...

In face of future climatic conditions, methods to ensure the success of forest plantation in warm and dry conditions are required. Mechanical site preparation (MSP) prior to planting is widely used around the world to enhance seedling establishment success. Our study aimed at identifying, among a set of MSP methods that are used in practical forest...

Le renouvellement de nombreuses essences d’intérêts économique et écologique est remis en cause par une hausse généralisée des populations de cervidés et des dégâts qu'ils occasionnent. La simulation d’abroutissement est une méthode expérimentale consistant à combiner la section mécanique de la plante et l’application de salive de cervidés sur la z...

In face of future climatic conditions, methods to ensure the success of forest plantation in warm and dry conditions are required. Mechanical site preparation (MSP) prior to planting is widely used around the world to enhance seedling establishment success. Our study aimed at identifying, among a set of MSP methods that are used in practical forest...

Suite au passage de la tempête Lothar en 1999, deux observatoires ont été mis en place dans le Nord-Est de la France pour caractériser la dynamique spontanée de recolonisation forestière et aider les gestionnaires dans leur choix d’itinéraire sylvicole. Nous présentons ici l’évolution de la composition dendrologique, de la densité et des diamètres...

The relationship between the quality of forest seedlings and their outplanting survival and growth has long been recognized. Various attributes have been proposed to measure the quality of planted seedlings in forest regeneration projects, ranging from simple morphological traits to more complex physiological and performance attributes, or a combin...

Forest stand and environmental factors influence soil organic carbon (SOC) storage, but little is known about their relative impacts in different soil layers. Moreover, how environmental factors modulate the impact of stand factors, particularly species mixing, on SOC storage, is largely unexplored. In this study, conducted in 21 forest triplets (t...

Key message Fifteen species are most susceptible to require vegetation control during tree regeneration in the range of our study. Among these 15 species, Rubus fruticosus , Pteridium aquilinum , and Molinia caerulea cover each more than 300,000 ha of open-canopy forests. Context Vegetation control, i.e., the reduction of competitive species cover...

Increasing species diversity is considered a promising strategy to mitigate the negative impacts of global change on forests. However, the interactions between regional climate conditions and species-mixing effects on climate-growth relationships and drought resistance remain poorly documented. In this study, we investigated the patterns of species...

The increasing disturbances in monocultures around the world are testimony to their instability under global change. Many studies have claimed that temporal stability of productivity increases with species richness, although the ecological fundamentals have mainly been investigated through diversity experiments. To adequately manage forest ecosyste...

Heterogeneity of structure can increase mechanical stability, stress resistance and resilience, biodiversity and many other functions and services of forest stands. That is why many silvicultural measures aim at enhancing structural diversity. However, the effectiveness and potential of structuring may depend on the site conditions. Here, we reveal...

While the impacts of forest management options on carbon (C) storage are well documented, the way they affect C distribution among ecosystem components remains poorly investigated. Yet, partitioning of total forest C stocks, particularly between aboveground woody biomass and the soil, greatly impacts the stability of C stocks against disturbances i...

Pour fixer les idées, cet article propose quelques rappels et détaille les particularités des sols forestiers à nappe perchée temporaire : conditions de formation d’une nappe perchée, formation des traces d’hydromorphie, sensibilité au tassement et principales contraintes pour les essences forestières. Il aborde enfin les principaux enjeux auxquels...

Just as the aboveground tree organs represent the interface between trees and the atmosphere, roots act as the interface between trees and the soil. In this function, roots take-up water and nutrients, facilitate interactions with soil microflora, anchor trees, and also contribute to the gross primary production of forests. However, in comparison t...

With the rise of large herbivore populations in most northern hemisphere forests, browsing is becoming an increasingly important driver of forest regeneration dynamics. Among other processes affecting the regeneration, the concept of plant-herbivore feedback loops holds that browsed saplings are more subject to subsequent herbivory. This phenomenon...

Oak (Quercus petraea (Matt.) Liebl. and Quercus robur L. grouped), European beech (Fagus sylvatica L.) and hornbeam (Carpinus betulus L.) are three major species of western and central European forests. When conditions are suitable for the three species, silvicultural management often favours oak because of its greater economic interest. Forest man...

Modeling diameter distribution of Aleppo pine (Pinus halepensis Mill.) natural forest in the Aures (Algeria) using the Weibull, Beta and Normal distributions with parameters depending on stand variables Abstract: 230 temporary plots located in Aleppo pine (Pinus halepensis Mill.) stands in the Aures (Algeria) were used for modeling its structure wi...

L’observatoire des peuplements dévastés et mités mis en place quelques années après la tempête de 1999 a permis le suivi pendant 20 ans de la reconstitution forestière en l’absence de travaux sylvicoles. Le travail d’analyse des données propose des éléments de diagnostic sur la façon de discriminer les situations où la régénération naturelle est su...

The recruitment of forest trees is driven by both bottom-up processes (the acquisition of resources) and top-down processes (herbivory). To initiate stand regeneration, foresters commonly reduce tree density to increase light levels for seedlings and enhance primary productivity. These changes in vegetation dynamics, however, could also influence e...

Mechanical site preparation (MSP) is widely used in forestry to improve plantation success. Although it is known to alter soil properties, its direct effects on soil structure have rarely been described. The cultivation profile is a visual soil evaluation (VSE) method developed in agricultural research to analyse the impacts of cultivation practice...

Mixed forests are usually associated with higher aboveground carbon storage compared to the corresponding monocultures but information on the impact of tree species mixing on soil organic carbon (SOC) is still limited. Yet, maximizing SOC storage is crucial for ecosystem C sequestration and many other ecosystem services. This study used a triplet a...

Mechanical site preparation (MSP) is often performed prior to planting to improve the growth and survival of planted seedlings. In this study, we compared root development of 5-years-old Quercus petraea and Pinus nigra seedlings planted in plots that had been prepared with different methods, i.e. deep scarification, deep scarification combined with...

Promoting mixed forests is often seen as a management option to increase the resilience of forests to droughts. However, mixing can also improve tree growth, and if faster-growing trees use more water, they may be exposed to higher risks of drought. Across Belgium, we tested whether increased tree growth in mixed sessile oak/common beech stands res...

Mechanical site preparation methods that used tools mounted on lightweight excavators and that provided localised intensive preparation were tested in eight experimental sites across France where the vegetation was dominated either by (L.) Moench or (L.) Kuhn. Two lightweight tools (Deep Scarifier: DS; Deep Scarifier followed by Multifunction Subso...

There is a growing demand for moving towards sustainable agri-food systems which per nature covers a complex network of activities and domains; such systems will benefit from multi-criteria decision analysis (MCDA) methods. Although some reviews on MCDA in agri-food research have been published, none of them covered the whole value chain. In this a...

Tree species-mixing has been suggested as one option to counteract the adverse effects of global change on tree mineral nutrition, yet the effect of mixing on nutrient availability remains poorly documented. We therefore analyzed the current foliar nutrient (N, P, K, Ca, Mg) quantities and ilr balances (isometric log transformed ratios between elem...

Aim Climate change is known to be a driver of changes in forest plant communities and to modify disturbance regimes. We investigated whether forest gaps favoured vegetation adaptation to warmer climates by accelerating the shift of plant communities to a warmer‐adapted composition independently of canopy closure linked to natural forest dynamics....

Past failures of monocultures, caused by wind-throw or insect damages, and ongoing climate change currently strongly stimulate research into mixed-species stands. So far, the focus has mainly been on combinations of species with obvious complementary functional traits. However, for any generalization, a broad overview of the mixing reactions of fun...

Oak reproduction is characterized by mast seeding with high inter-annual fluctuations in fruit production. Such resource pulses can greatly affect ecosystem functioning and may cause seed consumers to alter their mobility, demography, or diet. Consequences of mast seeding for seed consumers remain poorly understood as their long timescale makes the...

Establishing mixed-species stands is frequently proposed as a strategy to adapt forests to the increasing risk of water scarcity, yet contrasted results have been reported regarding mixing effects on tree drought exposure. To investigate the drivers behind the spatial and temporal variation in water-related mixing effects, we analysed the δ¹³C vari...

Key message In a mixed, Fagus sylvatica L.- Acer pseudoplatanus L., young plantation, trees of both species absorbed water from superficial soil layers despite the presence of roots and water in deeper layers. Admixture proportion and tree density were weak predictors of water acquisition depth, as well as fine root vertical distribution, although...

Tree species mixing has been widely promoted as a promising silvicultural tool for reducing drought stress. However, so far only a limited number of species combinations have been studied in detail, revealing inconsistent results. In this study, we analysed the effect of mixing Scots pine and oak (pedunculate oak and sessile oak) trees on their dro...

This data article contains annotation data characterizing MultiCriteria Assessment (MCA) Methods proposed in the agri-food sector by researchers from INRA, Europe's largest agricultural research institute (INRA, http://institut.inra.fr/en). MCA can be used to assess and compare agricultural and food systems, andsupport multi-actor decision making a...

Key message In understory trees, height–diameter allocation is subject several constraints: maximal height growth is limited, height growth is never null and, in terms of time dependency, diameter growth always precedes height growth. Abstract Understory trees experience a succession of canopy opening and closure events during their lifetime. Pref...

Premise of the study: Thinning is a frequent disturbance in managed forests, especially to increase radial growth. Due to buckling and bending risk associated with height and mass growth, tree verticality is strongly constrained in slender trees growing in dense forests and poor light conditions. Tree verticality is controlled by uprighting moveme...

The relationship between forest productivity and tree species diversity has been described in detail, but the underlying processes have yet to be identified. One important issue is to understand which processes are at the origin of observed aboveground overyielding in some mixed forests. We used a beech–maple plantation exhibiting aboveground overy...

Context: Lowering stand density has been suggested to adapt forests to warmer and drier conditions. Whether common dendrometric rules used to guide growth models and support silviculture are still valid at these densities lower than usual needs be tested. This includes (1) estimating the stand growth-density relationship over wider density gradient...

Research into mixed-forests has increased substantially in the last decades but the extent to which the new knowledge generated meets practitioners’ concerns and is adequately transmitted to them is unknown. Here we provide the current state of knowledge and future research directions with regards to 10 questions about mixed-forest functioning and...

Abstract Competition with neighboring trees of different species can affect crown size and shape. However, whether intra-specific differences in crown characteristics in mixed stands compared to pure stands are dependent on site conditions remains poorly understood. We used terrestrial laser scanning (TLS) to examine the differences in Fagus sylvat...

Les effets de la densité du peuplement et de la sécheresse estivale ont été analysés sur la croissance en diamètre et en hauteur du Chêne sessile (Quercus petraea) à l’échelle du peuplement et de l’arbre. Les données des inventaires dendrométriques issues de deux réseaux d’expérimentations sylvicoles ont été utilisées (réseaux LERFOB et GIS Coop, 9...

Whereas improved tree mineral nutrition is known to be one driver behind the higher growth in mixed vs pure stands, the effects of stand density and admixture of species with limited functional dissimilarity remain very poorly documented. Our study therefore addresses the impact of local neighbourhood, including density and species composition, on...

La scarification du sol et le dosage du couvert forestier permettent de lever des blocages de régénération naturelle

Key message The position of trees in the canopy impacts xylem structure and its inter-annual variation. After canopy release, the increase in the hydraulic conductivity of growth rings was driven by an increase in radial growth in large trees, and by both an increase in radial growth and changes in xylem structure in saplings. Context Forest canop...

Key message Tree resilience to drought was higher in drier sites and lower for suppressed trees grown in higher density stands, highlighting the role of acclimation and selection in tree responses to drought. Abstract Ongoing climate change will drive more frequent drought events in the future, with potential impacts on tree community structure an...

In most mixed-species forestry systems, regeneration is a critical step for individual tree survival and species coexistence. Species coexistence is driven by the fine-scale spatial patterns and competitive abilities of species. In naturally regenerated mixed oak (Quercus petraea and Quercus robur: QP and QR, respectively) stands, species coexisten...

Ash dieback induced by Hymenoscyphus fraxineus has emerged as one of the most serious health problem for European forests in the last ten years. However, precise estimation of the mortality induced by the pathogen is still scarce and this hampers management of affected stands. In this work, we used data of several surveys done since 2010 in France...

Forest plantation is a major tool to adapt forest ecosystems to global change. Plantation failure that recurrently occur in some contexts, associated financial costs, the hard and repetitive nature of tree planting, and potential negative environmental impacts of forest plantation strongly reduce the use of plantation to regenerate forest stands. A...

Cette communication situe la recherche de nouveaux matériels forestiers de reproduction vis-à-vis de l’agenda climatique international et du développement de l’économie circulaire, en insistant notamment sur les limites de durabilité des filières énergies renouvelables concurrentes (dépendance aux matières premières). Elle décline ensuite les consé...

L’objectif de cette étude était d’appréhender la forme de la structure en diamètre de trois peuplements réguliers d’âge différent de Cèdre de l’Atlas ainsi que quatre autres représentant les stades de développement (fourré, gaulis, perchis et futaie adulte) occupant des surfaces variables dans la cédraie naturelle de Tikjda (Djurdjura, Algérie). La...

Biomass equations are a helpful tool to estimate the tree and stand biomass production and standing stock. Such estimations are of great interest for science but also of great importance for global reports on the carbon cycle and the global climate system. Even though there are various collections and generic meta-analyses available with biomass eq...

Le concept de « sylviculture proche de la nature » a joué un rôle important au cours des 30 dernières années, fournissant une doctrine et un mouvement à une volonté de changement dans les pratiques de gestion. Il a bénéficié, au moins pour la France, d'une conjonction efficace entre une contestation de l'ordre sylvicole établi dans l’après-guerre e...

Even-aged forest stands are competitive communities where competition for light gives advantages to tall individuals, thereby inducing a race for height. These same individuals must however balance this competitive advantage with height-related mechanical and hydraulic risks. These phenomena may induce variations in height-diameter growth relations...

This study aimed at evaluating alternative methods to ensure regeneration success in temperate low-mountain forest stands by (1) estimating the effects of seed availability, competition from the adult stand and from neighbouring vegetation and interaction with the litter layer on seedling density, and by (2) comparing the effects of various silvicu...

Key message Density was more important in shaping crown structure than neighbor species identity. Both species showed high crown plasticity at alternative levels, which may explain species coexistence in mixed broadleaved forests with functionally similar species. Abstract Understanding crown response to local competition is essential to predict...

Une ouverture soudaine de la canopée implique une modification complexe du microclimat auquel l’arbre est acclimaté. Si l’accessibilité aux ressources et donc le potentiel de croissance augmentent, l’augmentation des mouvements d’air, de température de l’air et du sol et l’absence des arbres voisins résultent en une demande d’évaporation ainsi qu’u...

Background and Aims There is considerable evidence for the presence of positive species diversity–productivity relationships in plant populations, but the population parameters determining the type and strength of the relationship are poorly defined. Relationships between species evenness and tree survival or species coexistence are not well establ...

Although light is a key factor in forestry, it is surprisingly seldom measured in day-to-day management of European forests. The spherical convex densiometer is a simple instrument that allows to evaluate the canopy openness (CO) by counting the number of ‘canopy’ dots on a grid lying on a convex mirror reflecting the canopy. In this contribution,...

Background and AimsThe coexistence of forest tree species has often been linked to differences among species in terms of their response to light availability during the regeneration stage. From this perspective, species coexistence results from growth-growth or mortality-growth trade-offs along spatial light gradients. Experimental evidence of grow...

Understanding how competitive interactions vary with distance, size and identity of neighbors during the regeneration stage is essential to evaluate the persistence of mixed-species stands.

The objective of the study was to analyse to which extent horizontal crown plasticity reduces inter-tree competition at stand scale, and how it relates to species growth strategy. Two components of crown plasticity defined at the individual tree level (crown shape distortion, CSD and crown displacement relative to stem, CRD) were analysed and their...

In recent years, there has been increasing interest in modelling of species abundance data in addition to presence data. In this study, we assessed the similarities and differences between presence-absence distributions and abundance distributions along similar environmental gradients, derived, respectively, from presence-absence and abundance data...

The area of forests planted with exotic tree species is increasing worldwide in order to fulfill various economic and environmental demands. Numerous species currently used in forest plantations are considered to be invasive in many parts of the world. Exotic plantation tree species are endowed with a series of life-history traits that are characte...

La production de bois energie necessite de prendre en compte la question de l'impact de la vegetation accompagnatrice sur le developpement de l'essence objectif. Toutes les fois ou la competition exercee par la vegetation est suffisamment intense pour risquer d'influer sur la production de biomasse de la culture dediee, des operations de gestion de...

In order to better understand the structure and composition of forest plant communities, we aimed to predict the abundance of understory herbaceous species locally at the stand level and according to different environments. For this, we seeked to model species distributions of abundance at a regional scale in relationship with the local stand struc...

By increasing resource availability, canopy opening enhances tree recruitment as well as the development of neighbouring vegetation. The proliferation of early successional and highly competitive vegetation may have dramatic consequences on seedling establishment. However, differences in competitive abilities have been shown among the plant growth...

With a thick graminoid carpet, natural tree regeneration may often be difficult, if not impossible. Until nowadays, vegetation control operations using selective and low cost herbicides were traditionally necessary to ensure tree regeneration success. The socio-economical context is leading to a major reduction of the authorized and used herbicides...

Forest tree saplings that grow in the understorey undergo frequent changes in their light environment to which they must adapt to ensure their survival and growth. Crown architecture, which plays a critical role in light capture and mechanical stability, is a major component of sapling adaptation to canopy disturbance. Shade-adapted saplings typica...

Growth characteristics and water uptake were compared on two forest grass species (Agrostis stolonifera L. and Deschampsia cespitosa (L.) Beauv.) to evaluate their potential competitive effects on young forest seedlings. The two grass species were grown in large containers under two watering regimes (regular irrigation that maintained the soil at f...

Interference between 1-year-old sessile oak (Quercus petraea (Mattus.) Liebl.) seedlings and two grass species (Agrostis stolonifera L. and Deschampsia cespitosa (L.) Beauv.) was evaluated during 3 years after seedling transplantation. The seedlings were grown in large containers under crossed levels of watering regimes (regular irrigation that mai...

The production of woody biomass must consider the question of the impact of the accompanying vegetation on the development of the target species. Whenever the accompanying vegetation competes to the extent that it might influence the yield of the dedicated biomass crop, it must be controlled. There Is a range of management methods that can be used,...

Canopy closure and soil characteristics are commonly used to explain regeneration distribution at local and regional scales, although very few studies take both factors into account. The combination of environmental variables defined at broad and local scales is necessary to provide regeneration distribution models with a small resolution (tree sca...

This review describes key regeneration characteristics of the genus Fagus as represented by its four most prominent species: F. crenata (F.c.), F. grandifolia (F.g.), F. orientalis (F.o.) and F. sylvatica (F.s.). Similarities and differences in the relevant life phases of these species are identified. Those are related to natural disturbance regime...