Jacques Rondeux

Estimating Dead Wood During National Forest Inventories: A Review of Inventory Methodologies and Suggestions for Harmonization

Efforts to assess forest ecosystem carbon stocks, biodiversity, and fire hazards have spurred the need for comprehensive assessments of forest ecosystem dead wood (DW) components around the world. Currently, information regarding the prevalence, status, and methods of DW inventories occurring in the world’s forested landscapes is scattered. The goal of this study is to describe the status, DW components measured, sample methods employed, and DW component thresholds used by national forest inventories that currently inventory DW around the world. Study results indicate that most countries do not inventory forest DW. Globally, we estimate that about 13% of countries inventory DW using a diversity of sample methods and DW component definitions. A common feature among DW inventories was that most countries had only just begun DW inventories and employ very low sample intensities. There are major hurdles to harmonizing national forest inventories of DW: differences in population definitions, lack of clarity on sample protocols/estimation procedures, and sparse availability of inventory data/reports. Increasing database/estimation flexibility, developing common dimensional thresholds of DW components, publishing inventory procedures/protocols, releasing inventory data/reports to international peer review, and increasing communication (e.g., workshops) among countries inventorying DW are suggestions forwarded by this study to increase DW inventory harmonization.

Review of indicators and field methods for monitoring biodiversity within national forest inventories. Core variable : Deadwood

Deadwood is one of the four elements taken into account in this review of indicators and field methods and is often considered as a key indicator of forest biodiversity. We have analysed the main types of surveys and have realised how greatly the needs and constraints used to monitor deadwood can vary among them. For instance, classical National Forest Inventories usually tend to avoid time-consuming collecting methods. In the wide variety of existing definitions of deadwood, such inventories require simple and clear definitions, especially in terms of quantified thresholds. Thus, deadwood is properly described by characterising several components, such as snags, logs, stumps, branches and fine woody debris. Deadwood sampling methods alter depending on the different components and dimensions considered (standing dead trees, lying dead trees and branches, etc. assessed quantitatively). Attributes such as tree species and stage of decay are used mainly to qualify the deadwood components. The deadwood volume estimations are usually based on classical approaches already applied to living or felled trees: volume equations and/or formulas giving the volumes of common geometric solids. The purpose of this paper is to focus on different deadwood assessment techniques and to provide the information necessary to identify the most relevant methods for collecting deadwood data. The latter is used to build indicators that characterise the evolution of forest biodiversity at the scale of large forest territories.

Site index curves and autecology of ash, sycamore and cherry in Wallonia (Southern Belgium)

Summary The work described in this article forms part of an exploratory study 1 whose aim was to determine the main aspects of the autecology of ash (Fraxinus excelsior L.), sycamore (Acer pseudoplatanus L.) and cherry (Prunus avium L.) in Wallonia (Southern Belgium). The potential productivity of these species was studied using the site index approach (the height a crop achieves at a given age) which is the most widely accepted means for estimating site quality. As a first step, a set of site index curves were constructed from stem analysis and semi-permanent plots data using the Johnson (1935) and Schumacher (1939) model for ash and the Duplat and Tran-Ha (1986) model II for sycamore and cherry. For ash, dominant height achieved at age 50 is related to various soil-site characters (through adequate multiple regression analysis) in order to make the predictions of site quality applicable to both forested and non-forested land. Furthermore the sites expressed through soil attributes are classified in ‘a site catalogue’ for each species according to their productivity level.

A decision support system to simulate and compare silvicultural scenarios for pure even-aged larch stands

In sustained forest management, it is particularly useful to test the adequacy of various silvicultural scenarios, but decision-making is also becoming increasingly complex because forest managers have to simultaneously meet several different objectives in response to society demands. In order to help forest managers make appropriate choices in silvicultural systems, we propose a SDSS (Silvicultural Decision Support System) that applies to pure and even-aged larch stands (Larix sp.) in lowland areas where site conditions are similar to those encountered in Southern Belgium. Its main purpose is (i) to predict the influence of silvicultural treatments on stand evolution and (ii) assist forest managers in comparing different scenarios with respect to predefined goals. This SDSS consists in three modules designed to elaborate silvicultural scenarios involving (i) stand growth prediction and thinning simulation; (ii) assessment of indicators selected to define the scenarios referring to wood production, financial, technico-economic and ecological components, tree stability and wood quality; and (iii) comparison of the scenarios on the basis of the set of previously assessed indicators (multi-criteria analysis). User-friendly “MGC_Larch” software helps managers to formulate, evaluate and compare different silvicultural scenarios for larch.RésuméUn système d’aide à la décision sylvicole (SADS) a été développé pour la sylviculture de peuplements équiennes purs de mélèzes [mélèze d’Europe (Larix decidua Mill.), mélèze du Japon (Larix kaempferi (Lamb.) Carr.), et mélèze hybride (Larix eurolepis Henry)] en Région wallonne (Belgique méridionale). Les objectifs de ce SAD sont : (i) de prédire l’influence de traitements sylvicoles sur l’évolution et la croissance des peuplements et (ii) de guider le choix des sylviculteurs vers un scénario répondant le mieux possible aux objectifs fixés. Ce système comporte 3 modules qui prennent respectivement en charge : (i) la simulation de la croissance en relation avec la densité de plantation initiale, le traitement sylvicole et la productivité de la station (construction de scénarios), (ii) le calcul d’un ensemble d’indicateurs caractérisant les scénarios et (iii) la comparaison par analyse multicritère des performances des scénarios en regard des indicateurs pris en considération. Les indicateurs utilisés sont de nature financière, technico-économique et écologique. Ils caractérisent la production ligneuse de manière quantitative et qualitative tout en évaluant les risques sylvicoles encourus en cas d’aléas climatiques (chablis). Le SAD est intégré dans le logiciel avec interface Windows appelé “ MGC_Larch ” (Make Good Choice for Larch).

Le Forestor Vertex: une nouvelle génération de dendromètres.

Si le mesureur de hauteur de Duhamel du Monceau utilise il y a plus de 200 ans (Parde et Bouchon, 1988) est forcement loin, les dendrometres tels que le Blume-Leiss et le Suunto (Rondeux, 1978) bases sur le meme principe trigonometrique viennent eux aussi de prendre un coup de vieux avec l’adoption de la technologie ultrasonique. Le “forestor VERTEX” (1), appareil suedois, inaugure cette nouvelle generation de dendrometres (2). Nous envisagerons successivement dans les lignes qui suivent la description de cet appareil (ci-dessous et p. 60), son principe de fonctionnement (pp. 60 et 61), les precautions particulieres quant a son utilisation (p. 62) et nous tenterons enfin de voir dans quelle mesure il represente ou non une acquisition interessante dans le contexte de la mesure des hauteurs d’arbres (p. 62).

Vegetation diversity assessment in Southern Belgium's permanent forest inventory.

A permanent forest inventory (IPRFW) was launched in 1994 in the Walloon Region to provide large-scale forest information for use in forest policy and forest management in Wallonia. This inventory is based on the sampling and measurement of permanent sample plots over a 10-year cycle. In 1997, various observations concerning biological diversity were integrated to characterise forest biodiversity, including deadwood, stand structure, forest margins, tree health status, soil properties and ground vegetation. These ecological observations were simply added to the existing data collection methods instead of conducting a thorough review of the inventory’s methodology and its internal organisation.

A Silvicultural Decision Support System to Compare Forest Management Scenarios for Larch Stands on a Multicriteria Basis.

In forest resource planning choosing a silvicultural scenario is becoming a complex problem especially due to the multiplicity of goals and wide-ranging criteria that forest managers have to consider in any decision making process (Diaz-Balteiro & Romero, 2008; Kangas & Kangas, 2005; Maness & Farrell, 2004). For a long time, research focussed on growth modelling aimed at describing stand evolution through the construction of growth models for even or uneven-aged stands. These tools are useful for predicting and analysing stand evolution over time but they are not designed to compare and help to select appropriate silvicultural scenarios. With reference to that, DSS (Decision Support System) is a computer application typically designed to address the multi-faceted nature of management questions. Every decision can affect criteria of various kinds like: environmental issues (e.g., biodiversity conservation, carbon sequestration,..), economic issues (e.g., timber, wood quality, source of energy, ..) or social issues (e.g,. recreation, employment,..). Considering the increasing complexity of new challenges in forestry such systems are very useful in a wide range of fields, especially in sustainable natural resource management, business planning, transportation, timber harvest scheduling, ... (Gordon et al., 2004 ; Reynolds, 2005). In this paper we propose a silvicultural decision support system (SDSS) which is an extension of this concept. It consists in the selection of a silvicultural treatment that fits the best to the objectives assigned to pure even-aged stands which are, in this case, larch plantations. This SDSS has been developed to predict the influence of silvicultural alternatives on larch stand evolution and help forest managers choose scenarios according to preset goals. It is made of three interconnected modules designed for (i) growth prediction based on initial stand density, thinning regime and site index (scenario building), (ii) assessment of a set of indicators defining scenarios, and (iii) comparison of scenarios according to appropriate indicators using a Multi-Criteria Decision-Making – MCDM approach (Pauwels et al., 2007). Financial, technico-economic and ecological or environmental indicators are calculated in order to characterize wood production both qualitatively and quantitatively at the stand level. The SDSS is integrated into a user-friendly software package called “MGC_Larch (Make Good Choice for Larch)”. It has been developed for pure and even-aged larch stands

Tarif de cubage "peuplement" pour les mélèzes en belgique méridionale

Rev. For. Fr. LI 5-1999 605 Les tarifs de cubage “peuplement” permettent d’estimer directement le volume sur pied, ramene a l’hectare, d’un peuplement a partir de caracteristiques dendrometriques aisement recoltables telles que la hauteur dominante et la surface terriere. Ils s’averent particulierement utiles dans les problemes d’amenagement forestier et d’evaluation des ressources forestieres, plus precisement lors d’estimations globales et rapides du materiel ligneux sur pied (Rondeux, 1977).