In the first, endemic species abound and the biodiversity is very specific and/or very rich while the second type are generally in the form of  uncultivated land only harboring ruderal species. A typical example would be the suburbs of African megalopolises, completely cleared for the supply of timber. At first glance, it might appear that these zones could lend themselves to the reforestation envisaged by agencies and UN-type programmes such as UNEP (United Nations Environment Programme) or REDD (Reducing Emissions from Deforestation and Forest Degradation).

A specific photosynthesis

A first step has been taken towards a better knowledge of grassland ecosystems. Published last December in Frontiers in Ecology and Environment, an article (2) written by the same signatories as those to Science attempts to define the traits common to all the ancient tropical grassland ecosystems whatever part of the world is in question: Australia, California, South America, Tropical Africa… “The main criteria demonstrated to date are an increased richness of grassland species, a level of endemism (that is to say that a large part of the species are only found here) and the high presence of xylopodia (which grows on wood). It could be considered to be a form of adaptation to extreme environmental conditions such as droughts or repeated fires. But this is only the beginning: other integrated studies are necessary if we are to management tools and later, restoration tools that are truly efficient and specific to these environments”. At the Biodiversity and Landscape Unit of Gembloux Agro-Bio Tech alone, four or five people work full-time on this type of characterization, on vegetation types that are linked to copper flora and woodlands.

Grégory Mahy insists: this type of appeal not to proceed too hastily with reforestation programmes is not an attack on the pertinence of programmes such as REDD+. “Forests, their protection and restoration are without doubt powerful tools for carbon trapping. We are simply drawing attention to the questions as to how and where to proceed. It is indispensable to have a mapping on the scale of sub-regions that are much finer than the current map used by the UN. It would be regrettable if the latter succumbed to the temptation to give guarantees to providers of funding or to focus too much on the proposed forest restoration programmes and thereby applying mechanically applying solutions that have worked in the past. If we do not pay attention, we are heading for a collision between two essential imperatives: the conservation of biodiversity – we believe that by the end of the century, 40% of animal and plant species will have disappeared – and the struggle against climate change. There can be no winner here”. 

(2) Toward and old-growth concept for grasslands, savannas, and woodlands, Frontiers in Ecology and Environment, 2015