FORHET Team: Heterogeneous forests


Two key social challenges are affecting modern forests: the first is an energy challenge linked to the scarcity of fossil fuels and to climate change; the second is the need to improve environmental conservation. For this reason, one of the aims of the Grenelle Environment Round Table was to "produce more wood while improving biodiversity conservation."
Mixed forest stands can be part of the solution to this double challenge. In fact, a mixture of species has been shown to promote productivity in multiple forest situations, and intrinsically builds a welcoming environment for biodiversity compared to pure stands.
The Heterogeneous Forests team studies these complex systems in order to improve understanding of their performance and better characterize their productivity. Their work also provides decision-making support tools for forest managers in lowland forests (forestry method, clearings, regeneration and underbrush vegetation, etc.).
Mixed stand in the Forêt d’Orléans – photo Y. DUMAS

Since 2011, the team has focused on setting up a network of experimental sample plots in the state forest of Orléans with financial support from the Centre region and in partnership with the National Forest Office. The project is called OPTMix (Oak Pine Tree Mixture). The project was created to evaluate the advantages and disadvantages of potential forestry strategies on stand density and composition in a context of climate change. This project is unique in that it combines the study of the impact of these strategies with the presence of absence of wild ungulates.

For further information on the OPTMix project


The team mainly focuses on the various interactions within mixed stands. These can be interactions between individuals from the same or different species, in the tree stratum, underbrush vegetation or between the different strata within the ecosystem. The team uses two main approaches: modeling tree growth and dynamics, and resource sharing between individuals (light, water and nutrients).

Main Projects

Growth of mixed stands

Mixed forest growth is modeled on two scales:

  • We analyze growth data from experimental systems located mainly in the Forêt d’Orléans within a sessile oak and red fir mixture. This work provides insight into subtle mechanisms such as the impact of spatial structures on growth or the reaction of a species following biotic disruption to other species.



  • We also model how mixed stands grow in relation to environmental scales, making the most of the wide range of situations available in the National Forest Inventory data. This makes it possible to study variations in environmental interactions including climate issues.

By comparing a reductionist approach with a systemic approach, we have made progress towards generalizations about phenomena that affect how the mixture works.

Continuous cover forest regeneration dynamics linked to underbrush vegetation: use of resources

We need a better understanding of how forest systems work in order to improve our models on generalized growth and forest stand dynamics, especially the regeneration phase. We are therefore studying how resources such as light, water and nutrients are shared between different sections of forest ecosystems. Water is an increasingly important factor in the context of climate change. Our studies focus on two management scenarios anticipated by managers in this context:

  • reducing the number of growing trees and/or
  • implementing mixed stands, especially to reduce stand water consumption.

However, underbrush in these more open, brighter stands is quickly colonized by dense, monopolizing herbaceous plants and shrubs. We are studying and quantifying how much the plants consume in terms of resources (water, minerals, light) depending on the species that are present. We are evaluating their impact on ecosystem diversity (Imprebio project: the impact of the intensity of forest harvesting on biodiversity) and tree productivity. Finally, we are looking at interactions between these plants and the regeneration of young trees (negative competitive or positive facilitative relationships) to evaluate their impact on stand renewal dynamics. These investigations are all simulated in the RReShar (Regeneration and Resource Sharing) model, implemented as part of the Capsis platform to help formulate new management paths.

Typical stand growth and modeling

 The team is also working on modeling pure stand growth in partnership with the scientific interest group "Data Cooperative on Forest Stand Growth (oak, douglas fir and black pine).
We are also participating in the EMERGE project (Development of Models for Robust and Generic Estimation of Wood Energy). This project is part of the ANR Bioenergy program working to obtain robust and compatible volume, biomass and mineral mass models for various French species in various forestry management contexts.

An ongoing multi-partner project (2015-2017) funded by MAAF-DSF is currently looking at how black pine forestry in France is adapting to red band needle blight, a rapidly emerging health problem.

Large-scale modeling and simulation

Going from a plot to a regional scale makes it possible to consider societal issues such as land use and development, especially with regard to different goals such as wood production, carbon capture or biodiversity conservation. The aim of the 2010-2014 Forest Ecosystems Management (FORGECO) project and the ANR SYSTERRA program is to study the dual challenge of optimized wood production and environmental conservation on a regional scale. As part of this project, we are developing a growth simulator for large-scale pilot schemes, i.e., the Forêt d'Orléans and Quatre Montagnes area in the Vercors region. (SIMMEM Module, Multi-module large-scale simulator, implemented within the Capsis software platform).

Transfer and expertise

Wood and biomass energy availability in forests

One method for evaluating biomass availability in forests also estimates the quantity of wood-material and wood-energy that can be removed from forests in addition to current harvests without jeopardizing sustainable forest management and use.
Photo: Chopping firewood – photo D. Gauthier.

Growth and dynamics modeling

Growth and dynamics models have been implemented on the Capsis platform (black pine, scots pine, oak pine and RReShar). These models are mainly used when developing forestry guides for the National Forest Office.
3D diagram representing a forest model

Research topic

Terrestrial Ecological Systems: Dynamics, Vulnerability and Engineering

Research units

Forest Ecosystems


Leader Nathalie Korboulewsky
Researchers and engineers

Philippe Balandier
Yann Dumas
Nathalie Korboulewsky
Thomas Perot
Patrick Vallet

Assistant engineers

Catherine Menuet
Sandrine Perret
Vincent Seigner
PhD students Jordan Bello

Recent publications


  • Balandier P., Dumas Y., Gobin R., 2015. Fougère aigle et jeunes arbres: une cohabitation quasi impossible. Forêt-Entreprise, 221, 25-27.
  • Balandier P., Dumas Y., Gobin R., 2015. Biologie et Ecologie de la fougère aigle. Forêt-Entreprise, 221, 20-24.
  • Gobin R., Korboulewsky N., Dumas Y., Balandier P. accepted in 2015. Evapotranspiration strategies of four forest understorey plant species relative to drought intensity and their functional type. Annals of Forest Science.
  • Henneron L., Aubert M., Bureau F., Dumas Y., Ningre F., Perret S., Richter C., Balandier P., Chauvat M., 2015. Forest management adaptation to climate change: a Cornelian dilemma between drought resistance and soil macro-detritivore functional diversity. J. Appl. Ecol. In press.
  • Merlin M., Pérot T., Perret S., Korboulewsky N. and Vallet P., 2015. Effects of stand composition and tree size on resistance and resilience to drought in sessile oak and Scots pine. Forest Ecology and Management 339(0): 22-33.
  • Tetegan M., Korboulewsky N., Bouthier A., Samouëlian A., Cousin I., 2015. The role of pebbles in the water dynamics of a stony soil cultivated with young poplars. Plant and Soil. 391: 307-320.
  • Toïgo M., Vallet P., Pérot T., Bontemps J.-D., Piedallu C. and Courbaud B., 2015. Overyielding in mixed forests decreases with site productivity. Journal of Ecology(103): 502-512.
  • Toïgo M., Vallet P., Tuilleras V., Lebourgeois F., Rozenberg P., Perret S., Courbaud B. and Pérot T., 2015. Species mixture increases the effect of drought on tree ring density, but not on ring width, in Quercus petraea-Pinus sylvestris stands. Forest Ecology and Management 345: 73-82.


  • Adili B., El Aouni M.H., Balandier P., 2013. Influence of stand attributes and silviculture on cone and seed productions in forests of Pinus pinea L. in northern Tunisia. In: Mediterranean stone pine for agroforestry, Options Méditerranéennes, A, 105, 9-14.
  • Guillemot J., Delpierre N., Vallet P., Francois C., Martin-StPaul N. K., Soudani K., Nicolas M., Badeau V., Dufrene E., 2014. Assessing the effects of management on forest growth across France: insights from a new functional-structural model. Annals of Botany, 114:779-793.
  • Ligot G., Balandier P., Courbaud B., Claessens H., 2014. Forest radiative transfert models: which approach for which application? Can. J. For. Res., 44, 5, 391-403. doi: 10.1139/cjfr-2013-0494.
  • Ligot G., Balandier P., Courbaud B., Jonard M., Kneeshaw D., Claessens H., 2014. Managing understory light to maintain a mixture of species with different shade tolerance. Forest Ecology and Management, 327, 189-200.


  • Adili B., El Aouni M.H., Balandier P., 2013. Unraveling the influence of light, litter and understory vegetation on Pinus pinea natural regeneration. Forestry, 86, 297-304. Doi:10.1093/forestry/cpt005.
  • Balandier P., Marquier A., Casella E., Kiewitt A., Coll L., Wehrlen L., Harmer R., 2013. Architecture, cover and light interception by bramble (Rubus fruticosus), a common understorey weed in temperate forests. Forestry, 86, 39-46. Doi:10.1093/forestry/cps066
  • Ligot G., Balandier P., Fayolle A., Lejeune P., Claessens H., 2013. Height competition between Quercus petraea and Fagus sylvatica natural regeneration in mixed and uneven-aged stands. Forest Ecology and Management, 304, 391-398.
  • Ngo Bieng M. A., Pérot T., De Coligny F. and Goreaud F., 2013. Spatial pattern of trees influences species productivity in a mature oak-pine mixed forest. European Journal of Forest Research 132(5-6): 841-850.
  • Paillet Y., Chevalier H., Lassauce A., Vallet P., Legout A., 2013. Integrating fertilisation and liming costs into profitability estimates for fuel wood harvesting: a case study in beech forests of eastern France. Biomass & Bioenergy, 55:190-197
  • Pérot T., Vallet P.  and Archaux F., 2013. Growth compensation in an oak-pine mixed forest following an outbreak of pine sawfly (Diprion pini). Forest Ecology and Management 295(1): 155-161.
  • Pilon R., Picon-Cochard C., Bloor J.M.G., Revaillot S., Kuhn E., Falcimagne R., Balandier P., Soussana J.F., 2013. Grassland root demography responses to multiple climate change drivers depend on root morphology. Plant and Soil, 364: 395-408. DOI 10.1007/s11104-012-1371-8.


  • Da Silva D., Balandier P., Boudon F., Marquier A., Godin C., 2012. Modeling of light transmission under heterogeneous forest canopy: an appraisal of the effect of the precision level of crown description. Ann. For. Sci., 69, 181-193. DOI 10.1007/s13595-011-0139-2.
  • Pérot T. and Picard N., 2012. Mixture enhances productivity in a two-species forest: evidence from a modelling approach. Ecological Research 27: 83-94.


  • Ammer C.,  Balandier P., Bentsent N.S.,  Coll L., and Lof M., 2011. Special Issue: Forest vegetation management in the 21st century - current practices and future challenges. European Journal of Forest Research 130:1-133.
  • Gaudio N., Balandier P., Dumas Y., and Ginisty C., 2011. Growth and morphology of three forest understorey species (Calluna vulgaris, Molinia caerulea and Pteridium aquilinum) according to light availability. Forest Ecology and Management 261:489-498.
  • Gaudio N., Balandier P., Perret S., and Ginisty C., 2011. Growth of understorey Scots pine (Pinus sylvestris L.) saplings in response to light in mixed temperate forest. Forestry 84:187-195.
  • Gaudio N., Balandier P., Philippe G., Dumas Y., Jean F., and Ginisty C., 2011. Light-mediated influence of three understorey species (Calluna vulgaris, Pteridium aquilinum, Molinia caerulea) on the growth of Pinus sylvestris seedlings. European Journal of Forest Research 130:77-89.
  • Genet A., Wernsdörfer H., Jonard M., Pretzsch H., Rauch M., Ponette Q., Nys C., Legout A., Ranger J., Vallet P., Saint-André L., 2011. Ontogeny partly explains the apparent heterogeneity of published biomass equations for Fagus Sylvatica in central Europe. Forest Ecology and Management, vol. 261, no. 7, p. 1188-1202
  • Genet A., Wernsdörfer H., Mothe F., Bock J., Ponette Q., Jonard M., Nys C., Legout A., Ranger J., Vallet P., Saint-André L., 2011. Des modèles robustes et génériques de biomasse. Exemple du Hêtre. Revue Forestière Française, 63:179-190.
  • Ginisty C., Vallet P., Chevalier H., Colin A., 2011. Disponibilités en biomasse en forêt, en peupleraies et dans les haies pour le bois d’œuvre, d’industrie ou pour l’énergie. Evaluation à l’échelle nationale à partir des données de l'Inventaire forestier national et des statistiques de consommation de bois. Revue Forestière Française, LXIII :151-162.
  • McCarthy N., Bentsen N.S., Willoughby I., and Balandier P., 2011. The state of forest vegetation management in Europe in the 21st century. European Journal of Forest Research 130:7-16.
  • Ngo Bieng M.A., Ginisty C., and Goreaud F., 2011. Point process models for mixed sessile forest stands, Annals of Forest Science 68(2):267-274
  • Pérot T. and Vallet P., 2011. Mélange d'essences et productivité : application au mélange chêne sessile – pin sylvestre en forêt domaniale d'Orléans." Rendez-Vous Technique de l'ONF 33-34: 11-17.
  • Rivoire M., Longuetaud F., Saint-André L., Vallet P., Morneau F., Bouvet A., Gauthier A., Deleuze C., 2011. Une base de données unique en France de cubages d'arbres individuels (volumes, biomasses) au service d'une modélisation générique de la ressource en bois énergie. Revue Forestière Française, 63:171-178.
  • Tran-Ha M., Cordonnier T., Vallet P., Lombart T., 2011. Estimation du volume total aérien des peuplements forestiers à partir de la surface terrière et de la hauteur de Lorey. Revue Forestière Française, 63:361-378.
  • Vallet P. and  Pérot T., 2011. Silver fir stand productivity is enhanced when mixed with Norway spruce: evidence based on large-scale inventory data and a generic modelling approach. Journal of Vegetation Science 22(5): 932-942.


  • Berges, L., and P. Balandier. 2010. Revisiting the use of soil water budget assessment to predict site productivity of sessile oak ( Quercus petraea Liebl.) in the perspective of climate change. European Journal of Forest Research 129:199-208.
  • Pérot, T., F. Goreaud, C. Ginisty, and J. F. Dhôte. 2010. A model bridging distance-dependent and distance-independent tree models to simulate the growth of mixed forests. Annals of Forest Science 62:502.


  • Balandier, P., H. Frochot, and A. Sourisseau. 2009. Improvement of direct tree seeding with cover crops in afforestation: microclimate and resource availability induced by vegetation composition. Forest Ecology and Management 257:1716-1724.
  • Barbier, S., P. Balandier, and F. Gosselin. 2009. Influence of several tree traits on rainfall partitioning in temperate and boreal forests: a review. Annals of Forest Science 66:602p1-602p11.
  • Collet C., P. Balandier, T. Cordonnier, E. Dreyer, and P. Dreyfus, 2009. Raisonner la gestion des hêtraies mélangées. Biofutur, 305, 36-40.
  • Perret, S., Ginisty, C., 2009. Jusqu’où dynamiser la sylviculture du pin sylvestre en région Centre ? Les enseignements issus du réseau expérimental du Cemagref. RDV techniques 23-24: 3-13.
  • Vallet, P., C. Meredieu, I. Seynave, T. Bélouard, and J.-F. Dhôte. 2009. Species substitution for carbon storage: sessile oak versus Corsican pine in France as a case study. Forest Ecology and Management 257, 1314-1323


  • Barbier, S., F. Gosselin, and P. Balandier. 2008. Influence of tree species on understory vegetation diversity and mechanisms involved - A critical review for temperate and boreal forests. Forest Ecology and Management 254:1-15.
  • Chambelland, J. C., M. Dassot, B. Adam, N. Dones, P. Balandier, A. Marquier, M. Saudreau, G. Sonohat, and H. Sinoquet. 2008. A double-digitising method for building 3D virtual trees with non-planar leaves: application to the morphology and light-capture properties of young beech trees (Fagus sylvatica). Functional Plant Biology 35:1059-1069.
  • Gaudio, N., P. Balandier, and A. Marquier. 2008. Light-dependent development of two competitive species (Rubus idaeus, Cytisus scoparius) colonizing gaps in temperate forest. Annals of Forest Science 65:104p1-104p5
  • Nabuurs, G. J., E. Thurig, N. Heidema, K. Armolaitis, P. Biber, E. Cienciala, E. Kaufmann, R. Makipaa, P. Nilsen, R. Petritsch, T. Pristova, J. Rock, M. J. Schelhaas, R. Sievanen, Z. Somogyi, and P. Vallet. 2008. Hotspots of the European forests carbon cycle. Forest Ecology and Management 256:194-200.
  • Pérot, T., F. Goreaud, and C. Ginisty. 2008. Quels modèles de croissance pour les peuplements melangés? Exemple du mélange Chêne sessile - Pin sylvestre. Revue Forestière Francaise 60: 215-232
  • Provendier, D., and P. Balandier. 2008. Compared effects of competition by grasses (Graminoids) and broom (Cytisus scoparius) on growth and functional traits of beech saplings (Fagus sylvatica). Annals of Forest Science 65:510p511-510p519.