Organisms living in dead wood, hereafter called saproxylic(1),, consist in an important part of forest biodiversity. GEISER (1986) counts 1300 saproxylic beetle species in Western Germany, i.e. one third of all the forest Coleoptera living on this territory. Highly diversified and specialized communities of invertebrates and fungi live in dead wood. These organisms perform a critical role in ecosystem functioning as they recycle huge quantities of nutrients and are directly involved in the maintenance of forest soil fertility. One may estimate that about one third of nutrient release in surface soil layers comes from the action of saproxylic species (SWIFT 1977, AGREN 1986, HARMON et al. 1986).

Saproxylic organisms are directly concerned by the conservation of biodiversity in European forests. Recent studies clearly show that several thousands of saproxylic species are drastically threatened and are well represented on red data lists of European invertebrates as well as on the appendices of the EU directive habitat (Natura 2000) (GEISER 1986 ; SPEIGHT 1989 ; WARREN & KEY 1991 ; GOOD & SPEIGHT 1996). These taxa typically dwell in old forests, realize a narrow ecological niche and have poor dispersal ability. They are directly threatened by the "rejuvenation" and the fragmentation of old forests as well as by the adoption of intensive management practices that involve a systematic elimination of dead wood in forests, often cleared for hygienic reasons (WARREN & KEY 1991). As an example, provisional results indicate that the forests in Wallonie show a large deficit of dead wood : LECOMTE (2000) estimate the mean volume of fallen dead wood to 3.3 m3/ha to compare with 60 to 140 m3/ha in old natural forests (KIRBY et al. 1998). It can however be suspected that if a minimal dead wood availability could shelter some pest species, it can also shelter their predators and parasites allowing a better biological control of invasions.

Many elements are today lacking to understand the role of saproxylic organisms in forest ecosystem functioning : how do the dead wood rarefaction affect the communities of saproxylic organisms and the fertility of forest soils ? Moreover, we are not aware of the means to conserve diversified communities of saproxylic invertebrates : minimal dead wood volume, forest size, etc.

Methodology

- Enquiries sent to foresters to identify forest areas as habitats for diversified saproxylic communities, with tree species (oak/beech), availability of woody debris, and dead wood continuity in relation to past forest management history as the main criteria of selection;

- Enquiries sent to naturalists to gain better knowledge on the current distribution of flagship species, indicators of microhabitats and successional processes found in natural and poorly managed forests;

- Development of an insect sampling methodology based on a comparative analysis of capture efficiency among different kinds of traps used during the first year;

- Study of relationships between the number of saproxylic species and their abundance in forest with local (soil properties, vegetation structure and composition, climate, altitude, woody debris availability) and regional (landscape properties) ecological conditions;

- Bark sampling on recently logged beech trees to identify the main insect species and functional groups involved in their colonisation after death;

- Building of a web site to ensure accessibility and readability of the information for a larger audience, in particular regarding the importance of dead wood and saproxylic organisms in forest ecosystem functioning;

- Simulation of different management strategies and their effects on the economical value and multifunctional use of the forest.


Interaction between the different partners

The main objective of the project is to provide a global and multifunctional analysis of the results. This implies from the different partners to work in close co-operation during the whole research period, whether they are working on the field, identifying organisms at the Natural History Museum of Belgium, etc.


Link with international programmes

The research project does not fit into larger international programmes, although it benefits from continuous and dynamic exchanges with researchers from well-known European forest research institutes (Finland, France, Ireland, Portugal, Slovakia, Sweden).


Expected results and/or products

Besides a better understanding about the role that biodiversity plays in the recycling of organic matter in forest soils, this project aims to clarify the national distribution of saproxylic insects, to quantify their impacts in deciduous forests, and to identify the main determinants of their diversity. Results will be made available through national and international publications, a web site, and build-up of a centralised data bank from national biological inventories.


Partners

Activities

- Centre de Recherche de la Nature, des Forêts et du Bois (CRNFB), Ministère de la Région wallonne. Contact : Philippe Fayt, Biologist. Co-ordinator of the project, involved in the different steps, including information systems, enquiries and publications for a larger audience;

- Unité de Gestion et d’Economie Forestière (FUSAGx). Contact : Jean-Marc Henin, Forest Engineer, PhD student. Sampling, identification, analyses and writing. Study mainly the diversity and succession of insects which colonise dying and dead beeches (i.e. bark beetles and associated fauna);

- Unité d’Ecologie et de Biogéographie (UCL). Contact : Christophe Pontégnie , Forest Engineer, PhD student. Sampling, identification, analyses and writing;

- Departement Entomologie - Insecten (IRSNB). Contact : Veerle Versteirt, Biologist, PhD student. Sampling, identification, analyses and writing.


Coordinates/Details

- Dr. Marc Dufrêne, Centre de Recherche de la Nature, des Forêts et du Bois (CRNFB) – DGRNE – MRW, Direction de la Nature, de la Chasse et de la Pêche (Directeur P. Gérard), Avenue Maréchal Juin 23, B-5030 Gembloux, Tel: +32 (0)81 62 64 29; Fax: +32 (0)81 61 57 27, M.Dufrene@mrw.wallonie.be
- Prof. Jacques Rondeux, Faculté Universitaire des Sciences Agronomiques (FUSAGx), Unité de Gestion et d’Economie forestière, Passage des Déportés 2, B-5030 Gembloux, Tel: +32 (0)81 62 23 20; Fax: +32 (0)81 62 23 01, rondeux.j@fsagx.ac.be
- Dr. Patrick Grootaert, Koninklijk Belgisch Instituut voor Natuurwetenschappen (KBIN/IRSNB), Departement Entomologie - Insecten, Rue Vautier 29, B-1000 Brussels, Tel: +32 (0)2 627 43 02; Fax: +32 (0)2 627 41 13, Grootaert@kbinirsnb.be
- Prof . Lebrun, Université catholique de Louvain (UCL), Unité d’Ecologie et de Biogéographie (ECOL), Centre de recherches en Biodiversité (BDIV), Place Croix du Sud 5, B-1348 Louvain-la-Neuve, Tel: +32 (0)10 47 34 88; Fax: +32 (0)10 47 34 90, lebrun@ecol.ucl.ac.be


Users Committee

- Ir. Jos Van Slycken, Instituut voor Bosbouw en Wildbeheer
- Ir. Philippe Blérot, Division Nature et Forêt, Ministère de la Région wallonne
- Ir. Christian Gauberville, Institut pour le Développement Forestier (France)
- Ir. François Barr, Forêt wallonne