Photo : Adeline Bulot UMR IMBE
Photo : Adeline Bulot UMR IMBE

With the global economic and environmental crisis, ecological restoration is essential in order to scale up conservation actions. However, this restoration still too often uses heavy civil engineering techniques, which are the only techniques currently available to rebuild ecosystems. Yet such techniques are rarely applicable in developing countries. Will a new “ecological engineering”, based on the restoration of living organisms by living organisms, allow ecosystems to be restored and ensure that their exploitation by human beings is sustainable?

Review restoration techniques!

A number of ecological restoration operations have been implemented in recent years to address the destruction of ecosystems. The bulk of these operations do not aim to restore the original nature that existed before humankind, because this would lead to the latter being excluded from extremely vast areas. Their objective is more to rehabilitate components and functions of ecosystems in relation to the services they can render us, for example, soil fixation by plants to combat erosion and desertification, or the use of auxiliary organisms for crops in order to combat pests.

Active interventions are thus needed to recover the traditional exploitation regimes, which were often the source of cultural ecosystems or socio-ecosystems, such as hay meadows, pastoral rangelands, woodlands, terraced farming, etc. Indeed, the latter were often destroyed in the 20th century by intensive and industrial agricultural activities. These interventions often use heavy civil engineering techniques, comprising the use of construction site machinery. These techniques lead to a high consumption of non-renewable resources and polluting emissions. This means that they have significant economic costs and environmental impacts. They therefore cannot be transferred to developing countries.

Consequently, for several years now, researchers in restoration ecology have been recommending the development of a real “ecological engineering”, which aims to have a positive action for living organisms, but also to use living organisms to achieve this. This engineering is especially based on the use of organisms called “ecosystem engineers”, which may be plants, insects, fungi or bacteria. The aim of this is to optimize the functions of living organisms, such as atmospheric nitrogen fixation by certain plants in order to accelerate the restoration of the fertility of soils degraded by over-intensive agricultural practices.


Ecological engineering: to put “ecological” back into restoration

In developing countries, ecological engineering would certainly appear to provide an alternative in the sense that it is based on both scientific and empirical knowledge. It mobilizes certain traditional practices and thus more effectively integrates the restoration project among the local community. More specifically, ecological engineering aims to act on the ecosystem by injecting small quantities of energy, materials or actors, “the famous ecosystem engineers”, from which a “leverage effect” on the ecosystem is expected. There are already a lot of operational and successful examples of the use of ecological engineering to restore biodiversity, for example, the reintroduction of earthworms or termites to restructure soils. In many cities, the depollution generated by household effluents is thus provided by natural lagoon systems, based on the purifying capacities of plants rather than on wastewater treatment plants using physical and chemical treatments. Many living organisms have also already been used to optimize certain functionalities, such as the use of nitrogen fixing bacteria, mycorrhizae or plants that purify water and soils. Plant communities and landscapes have also been developed to promote the production of beneficial insects, not only by planting hedges, but also via a specific design of the landscape to combat the diffusion of the incriminated parasite!

This ecological engineering can also be envisaged on a very large scale, as is currently the case with the creation of the Great Green Wall in Africa. Its overall objective is to curb desert encroachment by developing Saharo-Sahelian areas. It also involves transforming land over the long term by establishing conditions that are conducive to the emergence of local organizations (communities, villages, tribes, etc.). Some of their sustainable production systems (agroforestry) will be capable not only of halting desertification, but also of eradicating poverty and food insecurity. The use of empirical knowledge is thus central to this project.


Ingénierie écologique et développement

Ecological engineering is in essence a sustainable development tool. The conservation of the last remnants of “virgin” nature and the restoration of corridors to link them are, of course, necessary in the North and South alike. Yet it is the application of the principles of ecological engineering in the rational use of natural resources and their recycling that can really ensure the sustainability of ecological restoration operations. Should the implementation of these operations therefore be based on implementing these interventions via international incentive policies, or rather revitalize certain traditional practices at local level by applying them to the creation and maintenance of ecosystems with a mutual benefit for humankind and the biosphere?

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