Elaboration de courbes de croissance en hauteur dominante pour les mélèzes (Larix decidua Mill. et Larix kaempferi (Lamb.) Carr.) en Belgique méridionale

in Annals of Forest Science : a Multidisciplinary and International Journal (1999), 56(1), 27-34

Site index curves have been determined for Japanese and European larch in Wallonia (Southern Belgium, figure 1). Seven models have been tested (figure 2) to adjust the data from stem analysis in 19 stands ... [more ▼]

Site index curves have been determined for Japanese and European larch in Wallonia (Southern Belgium, figure 1). Seven models have been tested (figure 2) to adjust the data from stem analysis in 19 stands for Japanese larch and in eight stands for European larch (table I). The mean squares of the models have permitted to compare each other (table II). The Duplat et Tran-Ha model IV is the most suitable to describe the dominant height growth. The information issued from 194 temporary plots (134 in Japanese larch stands and 60 in European larch) is used to determine five productivity levels based upon equal intervals of 3 m between 34 and 22 m of dominant height at 50 years (figures 3 and 4). Considering the little height growth difference between the two species of larch (figure 5 and table IV), a unique model is retained (table V). The growth speed is presented in figure 6. [less ▲]

Application d'un SIG à la révision du parcellaire dans le cadre d'aménagements forestiers intégrés

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (1998), 2(4), 271-279

Under intensive silviculture, forest management is based upon the delimitation of compartments (management units) usually defined as reasonably homogeneous stands regarding ecological, biological and ... [more ▼]

Under intensive silviculture, forest management is based upon the delimitation of compartments (management units) usually defined as reasonably homogeneous stands regarding ecological, biological and silvicultural conditions. Forest lands can often be managed for several uses, sometimes on the same area or sometimes with different dominant uses assigned to separate areas. A forest managed primarily for timber production can also serve other purposes. In that respect, it is often necessary to readjust the limits of management units so that environmental constraints (soil erosion, watershed protection) are taken into account. These considerations require specific silviculture. A geographic information system (GIS) is used to overlay provisional compartments map (management units) and different thematic maps that describe areas where environmental constraints are identified. Informations about these areas located inside the compartments are used in a classification process to decide which orientation is the most suitable allocation (in terms of objectives) for each management unit: timber production or protection (humid soils, slopes, rivers and sources). This process also indicates what are the limits of units that can or have to be modified. Such a classification has to be considered as a guide to build the final limits of management units according to the environmental criteria defined as a preliminary. The proposed methodology is applied to a 400 hectares forest. [less ▲]

Recreation Index Method

in Pelz, Dieter R. (Ed.) Forest management inventory systems in Europe (1997)

This paper describes the Recreation Index Method as it was developed by the "Faculté universitaire des Sciences agronomiques" during the research project AIR3-CT94-2327 financed by the European Commission ... [more ▼]

This paper describes the Recreation Index Method as it was developed by the "Faculté universitaire des Sciences agronomiques" during the research project AIR3-CT94-2327 financed by the European Commission. The projects name was "Development and harmonization of monitoring systems for forest resources management in Europe" and the objective was to design a set of inventory systems for forest resources management, applicable in all regions of the European Union for the optimal decision making in the production of multiple goods and services. Several universities and research institutes participated in this research. The "Faculté universitaire des Sciences agronomiques" focused its research on the design of a forest inventory method that enables foresters to assess the recreation function of woodlands. An extensive set of tools already exists for assessing the economic function (woods, production) of forests. Multiple descriptions of volume tables, taper functions, inventory systems, and others were published throughout times and these techniques have become common goods to foresters. However, until now, only very few tools exist for assessing the recreation function of a forest. The Recreation Index Method definitely changes this situation and is a substantial step towards the global evaluation of the recreation value of forests. The method that is described hereafter, produces objective indexes that reflect how well a forest or forest elements meet eh society's demand for recreation: the more a forest corresponds to the publics demand, the higher the recreation index will be. These indexes are calculated from three data sets: 1. Demand: the relative importance that the public attributes to th inventoried items; 2. Offer: an inventory of items in the forest that affect the recreation value of this forest; 3. Appreciation curves and their reference values: the equations that produce the recreation indexes from the inventoried number of items. The method requires an extensive set of data as well as dreadful calculations. The RECRE software was developed to automate the procedures of this method. The computer program stores all the necessary data and easily calculates all the Recreation Indexes. The software and the manual that comes with it are available from the European Community of from the Faculté universitaire des Sciences agronomiques (see address in annexes). Althouth the Recreation Index Method compares offer and demand, it does not take into account the external constrains that influence the offer, the demand, and the interaction between both. Budget and personnel constrains typically influence the offer, while reputation and publicity often modify the demand. Accessibility, extremely high social pressure (especially near cities), vandalism, and even crime are important factors that determine how offer and demand will interact. Considering all those external constrains highly complicates the forest recreation problem. But, before investigating on these external constrains, one may want to know more about the intrinsic value of a forest. That's the important role of the Recreation Index Method. [less ▲]

Modélisation de la croissance et du développement de la régénération naturelle des hêtraies du sud de la Belgique

Scientific conference (1996, June)

A model dealing with the natural regeneration dynamic of uneven-aged beech stands (Fagus sylvatica L.) has been developed for the South part of Belgium. This model, which is distance independent, predicts ... [more ▼]

A model dealing with the natural regeneration dynamic of uneven-aged beech stands (Fagus sylvatica L.) has been developed for the South part of Belgium. This model, which is distance independent, predicts radial and height growth of installed young trees (height > 30 cm) in relationship with individual parameters and surrounding mature stand density. This model also describes natural mortality in regeneration groups in relationship with dominant girth of these groups. A competition index has been created to combine the effect of both mature tree density in the vicinity of the groups and the groups and the social position in these groups on radial growth of the young trees. This index corresponds to a sum of basal area per ha of competing trees, the pressure of each competitor being weighted by the difference of size between the subject and competitors. The resulting model explains more than 65 % of radial growth variability. It is designed to work in connection with another tree-based distance independent model describing mature tree (girth at 1,5 m > 40 cm) growth associated with a simulator of silvicultural operations (thinnings) applied to the stand. [less ▲]

Incidence du martelage sur l'exploitation mécanisée des premières éclaircies résineuses

in Silva Belgica (1996), 103(6), 7-14

Développement d'un modèle de type arbre appliqué à la croissance des peuplements feuillus irréguliers du sud de la Belgique

in Canadian Journal of Forest Research = Journal Canadien de la Recherche Forestière (1996), 26(10), 1838-1848

A model predicting circumference growth of individual trees has been developed for mixed irregular stands dominated by Fagus silvatica L. in southeastern Belgium. This model integrates simultaneously tree ... [more ▼]

A model predicting circumference growth of individual trees has been developed for mixed irregular stands dominated by Fagus silvatica L. in southeastern Belgium. This model integrates simultaneously tree, stand, and growing site characteristics without considering distances between individual trees. It has a determination coefficent of 40.1 % and a residual standard deviation of 0.45cm/year. Forest mensuration variables considered in the model are circumference, tree social position represented by the total basal area of trees greater than the subject tree, stand basal area, and some index of stand structure corresponding to the ratio of the variance over the mean circumference. The site component is essentially expressed by the length of the growing period. The low accuracy obtained for individual tree growth is relative because the results are used mainly after individual trees have been distributed into size classes. We have been able to show that the introduction of crown description in the model can increase its accuracy. But this modification requires a submodel describing crown changes over time. [less ▲]

Modélisation de la croissance et du développement de peuplements forestiers d'âges multiples : application à la hêtraie wallonne.

Doctoral thesis (1994)

The present study aims at designing a system predicting the growth and development of uneven-aged forest stands; it has been applied to beech stands in Southern Belgium. This study is made up of three ... [more ▼]

The present study aims at designing a system predicting the growth and development of uneven-aged forest stands; it has been applied to beech stands in Southern Belgium. This study is made up of three main parts. Following a bibliographical research about state-of-the-art of forest growth models, the first part deals with the development of a distance-independent tree growth model. This describes adult trees (girth > 40 cm) girth increments at breast height, according to variables connected with, on the one hand, tree measurement and social position, stand density and structure and, on the other hand, site and ecological features, mainly the length of vegetation period. Considering irregular stand structure and the predominance of natural regeneration, we have been interested in evaluating the feasibility of a model describing the growth and the evolution of such a regeneration in beech stands. The results achieved in this second part allow us to use a distance-independent model which is in agreement with the model describing adult trees growth. The last part of this study deals with the development a simulation software integrating both "adult trees" and "regeneration" models, as well as a procedure wich prescribe and carry out thinnings in stands whose growth is simulated. An user-friendly menu driven interface allows this software to be used by forest managers. Appropirate outcomes of the simulator give an idea of the potentialities of such a powerful tool in modern forest management, provided it is adapted to the main hardwood species of the Wallonian forest. [less ▲]

Construction d'un modèle de répartition des arbres par classes de grosseur pour des plantations d'épicéa commun (Picea abies L Karst) en Ardenne belge

in Annales des Sciences Forestières (1994), 51(1), 53-65

The construction of a girth distribution model for Norway spruce (Picea abies L Karst) plantations has been considered using 141 sample plots of 1 000 m². The effects of the theoretical distribution ... [more ▼]

The construction of a girth distribution model for Norway spruce (Picea abies L Karst) plantations has been considered using 141 sample plots of 1 000 m². The effects of the theoretical distribution (comparison of the normal and Weibull distributions) and the estimation methods have been analysed. Despite the higher flexibility of the Weibull distribution, its use does not lead to a more accurate prediction of the distribution. The small number of samples measured in the plots seems to be the primary cause of the inaccuracy of the various models. Considering the data analysed, the normal distribution, which is easier to use, is proving to be more suitable for the creation of distribution model for such stands. [less ▲]

Utilisation d'un S.I.G. pour la gestion des ressources forestières : exemple d'application à un inventaire forestier régional

in Bulletin des Recherches Agronomiques de Gembloux (1993), 28(2-3), 275-286

The development of a Geographic Information System (G.I.S.) leads to new prospects in the field of broad-scale forest inventory, the main objective being to estimate areas and growing stock for the ... [more ▼]

The development of a Geographic Information System (G.I.S.) leads to new prospects in the field of broad-scale forest inventory, the main objective being to estimate areas and growing stock for the different stand types in a given region. The dot grid method typically used to estimate the areas in the case of systematic sampling, can be advantageously replaced by the creation within a G.I.S., of a stand map, that can be overlaid with data issued from the inventory. A methodology is proposed, to produce such a map using color infrared aerial photos at a scale of 1:25,000. Geographical data are processed using ILWIS software. The method has been tested on a 200 km² forest area. The error rate for interpretation of stand types is less than 6 % if one considers the confusions between species. The crossing of this stand map with the sample plots layer provides an estimation of the growing stock per stand type. [less ▲]

Tarifs de cubage peuplement pour le douglas Pseudotsuga menziesii (Mirb.) Franco en moyenne et haute Belgique

in Revue Forestière Française (1991), XLIII(6), 507-513

L'estimation rapide du volume des peuplements de nos principales essences forestières peut être réalisée au moyen de tarifs de cubage de peuplements. Nous avons mis à profit de grand nombre de données ... [more ▼]

L'estimation rapide du volume des peuplements de nos principales essences forestières peut être réalisée au moyen de tarifs de cubage de peuplements. Nous avons mis à profit de grand nombre de données dendrométrique récoltées dans le cadre d'une étude consacrée à la sylviculture et à la production du Douglas, pour établir des tarifs adaptés à la détermination du volume des peuplements de ce résineux en pleine expansion et qui couvre aujourd'hui près de 11 000 hectares en Moyenne et Haute Belgique. Nous présenterons d'abord les caractéristiques du matériel expérimental ainsi que la technique de construction des tarifs et nous fournirons les résultats obtenus pour le volume bois fort tige ainsi que ceux relatifs à différentes découpes, et, nous envisagerons enfin l'utilisation pratique de ces tarifs et rappellerons leur intérêt en matière de gestion forestière. [less ▲]