Establishing rigorous carbon inventories in forest environments is a key element in the strategy for combatting global warming. Following completion of his doctoral thesis, Jean-François Bastin has shown that it is possible to establish carbon inventories much more quickly and efficiently than before, with minimal loss of precision. This gain in terms of efficiency opens up vast possibilities with regard to the conservation and management of tropical forests.
Tropical forests play a fundamental part in the struggle against global warming and they are likely to continue to do so in the future. Tropical forests, whether they are in South America, Africa or Asia, need to be protected or even restored when they have been damaged in order to reinforce their ability to store the gigantic quantities of excess carbon released into the atmosphere due to human activity. The countries concerned sometimes have a tendency to overexploit the forests in the interest of development at any cost and short-term profit.
To enable them to adopt a more sustainable approach, international environmental agencies, encouraged by the Conference of the parties to the United Nations Framework Convention on Climate Change (COP – the next sitting is in Paris at the end of November), have set up programmes such as REDD: “Reducing Emissions from Deforestation and Degradation”, in developing countries. The key idea: if a financial value is attributed to carbon-rich forest basins, those who protect them or who accentuate their “sequestration” of carbon can be recompensed through “carbon credits”.
There has always been a lot of debate surrounding this commodification of the environment. But whatever the nature and relevance of this debate, this much is clear: if real progress is to be made in the implementation of conservation programmes in tropical forests, access to rigorous scientific data on the stocks of carbon in the different types of forest (rainforest, dry, mountainous, etc.) is imperative. To succeed in this, it is imperative to establish their carbon levels.
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Fastidious measures
It is here that the work of Jean-François Bastin, a researcher in the Department of Biosystems Engineering (Biose) of Gembloux Agro-Bio Tech (University of Liege) and at ULB (Laboratory of Ecology and Plant Production Systems), which was recently published in the journal Scientific Reports (1), becomes important. The initial impetus for this work was based on a pragmatic observation and intuition. Firstly, the observation: calculating the carbon levels of a tropical forest is a slow, fastidious and costly process. Once the sampling site has been delimited, all the trees therein must be measured (diameter and total height) of more than 10 cm in diameter to a height of 1.30 metres, and a long series of operations needs to be carried out: determination of the tree species, extraction of wood samples, creation of herbariums etc. In total, each hectare (the ideal surface area for this process in central Africa) counts an average of around 400 trees to be characterised in this way. This teamwork requires the presence of specialised professionals in the forest (botanists, forestry experts, logistics experts etc.) for an average period of five to six and up to ten days if permanent forest inventories are to be established. In other words, implementing such a programme is difficult not to mention the fact that the work takes place in very trying conditions of high temperature and humidity!
Certainly, this meticulous work is usefully completed by remote sensing. “By combining satellite images with the field information, we can design models which enable us to extrapolate the distribution of carbon stocks in the forest studied”, explains Jean-François Bastin. “The problem is that remote-sensing technology is still seriously lacking in some respects and despite efforts made in recent years, Africa is sadly lacking in parcels of forest that have been characterised in a sufficiently thorough and standardized way to enable real monitoring of forests on a continent-wide scale”.
The young researcher drew his initial intuition from a preliminary field mission to the dense forests of the Democratic Republic of the Congo (DRC). “I often wondered if, one day, it might be possible to discover a global indicator which would be sufficient in itself for measuring the state of a forest and, more particularly, estimating its carbon inventory without having to carry out all these measurements. A little utopian, undoubtedly, but I wanted to try out the idea at least…”
