The establishment of a genuine spatio-temporal (executive) information system of the Sart Tilman forest site is underway. The objective: reinforcing the ecological potential of the university site and to have it play, through a tailored management programme, a multifunctional role likely to be closely studied by numerous students. Tomorrow or after tomorrow the estate might have changed (a little) its appearance. But it will be (a lot) stronger in order to face the threats which hang over the forest. And to continue its role of being a green lung for the Ardent City.

Few universities, in Europe, can boast of occupying a green space of close to 750 hectares nestling in immediate proximity to a city of the size of Liège. Half a century ago, in establishing themselves on the heights of the Ardent City the ULg’s authorities already had the ambition of creating a vast green lung, contrasting with the industrial swarm of the Meuse valley and de facto restricting the building encroachment of a city undergoing full expansion. Today, whilst frequented on a daily basis by a population estimated to be around 20,000 people, the site to some extent can be understood as a semi-urban forest, a site for walking and relaxing (and working) for the whole of the personnel concerned by university life, from either close up or from further away.

But there you have it: a forest, in our latitudes, takes some managing. ‘If we want this wooded area to still be around in fifty years and to be still continuing fulfilling its various functions, we have to intervene in it,’ estimates Jacques Rondeux, an Emeritus Professor who was charged by the academic authorities two years ago to think over the sustainable development of the forest part of the Sart Tilman estate. Apart from upkeep and securitisation (fallen trees, storm damage, cut of hedges, etc.), no silvicultural intervention has taken place there in half a century. Many trees are in a state of advanced senescence. The current configuration of this woodland – coppice with standards – is little by little disappearing. In intervening parsimoniously and prudently, we could give this forest a more youthful character and have it develop into an irregular selection high forest, with higher stability, richer in terms of plant and even animal biodiversity."

205 hectares monitored

Intervene, certainly. But where and how? With what methodology? To answer these questions, Jacques Rondeux and his colleagues (1) at the Forest and Nature Management Unit, which he has led for close to thirty years at Gembloux Agro-Bio Tech, at first got down to the task of studying 205 wooded hectares which are valuable in terms of exploiting the woody biomass, particularly as far as energy valorisation is concerned. This surface area results from the deliberate elimination from it of the all zones considered to be non-exploitable, either because they are assigned to socio-recreational activities, or because they have been reserved for the conservation of the biodiversity – the site includes various natural reserves, as well as an arboretum and a botanical garden. These 205 hectares have been subject to a dendrometric inventory, enriched by silvicultural and ecological data based on systematic sampling. ‘Sample plots’ (in other words circular sampling units) of 3 ares and a radius of 10m were established at 107 fixed points spread over two configurations in squared grids of 200 metres by 200 metres. Each of these  points (one every two hectares) were permanently marked in a very visible way by metal stakes so that they could be regularly reused in the future. In each of these plots every standing tree was identified and subject to height and   circumference measurements. Other parameters were also taken into account: tree species, stand types, natural  regeneration, state of health, visual quality (fitness for fuel wood, timber, etc.). The lying and standing deadwood was also stock listed, as well as its stage of decomposition, judged according to a series of scientific criteria.

(1) With the precious work of T. Schillings, together by C. Dufays, C.Geerts, F. Henrotay, B. Mackels, C. Mengal , A. Monseur and A.Schot - Unité de Gestion des Ressources forestières et des Milieux naturels, ULg,Gembloux Agro-Bio Tech.