A green lung which needs revitalising

Such an undertaking could also contribute to the – very contemporary – problematic of energy savings and the reduction of CO2 emissions. Certainly burning wood releases carbon dioxide into the atmosphere, but the itself has enabled carbon to be stored for very long years. ‘In the case of the Sart Tilman site, the average calorific value per cubic metre ranges from 8,800 to 9,000 Mj/cubic metre,’ adds Jacques Rondeux. ‘We could thus produce annually on the area defined, at the strict minimum, the equivalent of 100,000 litres of fuel, whilst the figure of 200,000 is perfectly conceivable.’ Other scenarios are also possible: one could imagine that a small proportion of the wood gathered in the forest, instead of being used for fuelwood, is used for timber of the highest economic value, (joinery work, construction frameworks, etc.) and whose sales proceeds would enable investments in silvicultural operations:cleanings, plantations, thinnings, etc. One could also imagine short-rotation coppice plantation (SRC). The SRCs are trees of small size and/or rapid growth, such as willow and poplar, to be cut down every seven to eight years. They could be planted in the 7 hectares of weed zones included in the site, for example under overhead power transmission lines, or on terrains with no particular occupancy or which only need to be valorised. Whilst on the subject, let us point out that such a biomass heating system could allow the ULg’s buildings’ CO2 emissions to be reduced by 100 to 400 tons, depending on whether the heating is a fuel/wood mix or strictly fed by woody biomass. In other words from 0.13 to 0.49% of the total of the ULg’s building property.

Seeing trees crash to the ground or hearing the roar of chainsaws at the Sart Tilman might take some getting used to. ‘We are perfectly aware of that,’ responds Jacques Rondeux. ‘But let me be clear that this type of prudent and sensible exploitation will not fundamentally disturb the calm of the sites in question, or even ruin the massif’s appearance. Every forest which is today managed sustainably integrates the productive and economic function within a multi-functional frame. The latter, moreover, has been targeted by the academic authorities since the site’s creation, as it was a question of combining the recreational, aesthetic, scientific and teaching functions as well as those linked to nature conservation. The Sart Tilman forest regeneration will ensure the continuity of the forest and create a landscape dynamic. In a word: showing that a forest ‘lives’ and that it is for example capable of reinforcing its capacity to store carbon. A tree which is close to death in effect emits about as much CO2 as it absorbs.’


Another advantage: the permanent inventory of the forest resources, applied since April 2012 and concerning the whole area (540 hectares), can already serve as a support for numerous scientific activities, including the work and the training of students in different disciplines. One can well imagine end of degree projects looking into better understanding the carbon stock present in the litter bedding, or comparing the evolution of an ageing coppice-with-standards to that of a zone of a similar  characteristics but subjected to various silvicultural techniques, studying the recolonisation of exploitation gap zones by natural vegetation, evaluating the potential role of a short rotation coppice in the tertiary purification (nitrogen and phosphorous) of the waste water discharged by certain of the campus facilities, etc.

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