29/01/2010 - Article
In the face of global change, biodiversity is the keystone of development for current and future generations of humanity. Interview with Philippe Feldmann, Biodiversity Adviser at CIRAD, about how we can manage biodiversity and make optimum use of genetic resources.
Biodiversity is a complex concept, encompassing many possible interpretations. What is currently the favoured approach for conserving or managing biodiversity?
Philippe Feldmann: In the light of the changes everyone on Earth is now facing, we are currently trying to determine how biodiversity could help humanity develop, both now and in future. What we need to do is look at biodiversity in terms of what it could allow us to do, and assess the services it renders. In this respect, biodiversity can be seen as a life insurance policy for humanity: by maintaining biodiversity, we will also be able to maintain our capacity to adapt to new conditions that we cannot necessarily predict but that could nevertheless affect us in the near future.
How are researchers going about maintaining biodiversity?
P.F.: The first thing we need to do is understand how biodiversity works. As things stand, human activity has already had a significant impact. For instance, many areas on islands, which are often biodiversity hotspots, now have just a fraction of the diversity that used to exist. Nevertheless, despite these adverse effects of human activity, there is often still a substantial amount of biodiversity left that could render services. To take the example of genetic resources, there are two main ways of maintaining diversity: in situ management, which consists in keeping maintaining genetic diversity in the natural environment or on "farms" and calls for very large areas, often in zones that are difficult to protect; and another solution, which is almost certainly less effective but easier to implement: ex situ genetic resource collections. In the French overseas regions in the tropics, there are many such collections: yam, banana, sugarcane and pineapple in the West Indies, and in Réunion, vanilla and lontan vegetables, which are traditional crops.
How can these resources be promoted and used?
At present, for a given species, using a range of genetic resources, we can breed species that will be suited to new conditions in future: climatic conditions or others linked to human requirements. For instance we will no doubt need plants that will not produce food but fibres or other molecules. We will also have to adapt to new diseases that may emerge.
Agro-ecologists, for their part, are trying to optimize our knowledge of the natural interactions within biodiversity in order to develop sustainable cropping systems that require fewer inputs. We can use less fertilizer by fostering or making optimum use of the range of soil microorganisms that naturally produce the elements required for plant development and control the development of certain parasites and pathogens. Observations of what goes on the natural environment are pushing us, for instance, towards biological control or cropping techniques that enable us to grow varieties that are more tolerant when mixed with others. We know that if we grow different varieties of the same species in a given field, some diseases can no longer develop. We also have other solutions consisting in working on a territory level and combining different crops. This approach also serves to optimize the natural resources found in the soil and to guarantee yields. Agroforestry is another example of a method traditionally used in many tropical countries in an attempt to optimize the interactions between species.
Interview by Elsa Bru
Biodiversity is a complex concept
that encompasses a large number of possible interpretations. Conventionally, a distinction is made between three main levels of biodiversity:
Intraspecific diversity , corresponding to genetic diversity: the diversity within populations and species. Interspecific diversity , corresponding to the diversity between species, which can be estimated for instance based on the number of species in a given environment. Ecosystemic diversity , hence the interactions between these different levels and different species: this level can be seen as the most important, since it governs the capacity to evolve or adapt.
A biodiversity hotspot is a geographical zone containing at least 1500 endemic plant species but that has already lost at least 70% of its previous species, at least in their original state.
Hotspots account for just 2.3% of the Earth's total area. At present, 34 zones are hotspots. More than 50% of plant species and 42% of terrestrial vertebrate species live in these hotspots (source: www.biodiversityhotspots.org).
Réunion, Mayotte, Guadeloupe, Martinique, New Caledonia, Polynesia and Wallis and Futuna are split between four hotspots, while metropolitan France has just one: the Mediterranean.