We see posters everywhere announcing the restoration of a quarry, cleaning soil poisoned by lead, the underpinnings of some dunes… but do we really serve these actions? A scientific team anglohispano had this question, and after consideration of 89 initiatives focused on very different ecosystems, has concluded that it is effective: its positive impact has resulted in an increase in biodiversity of 44% and an increase of 25 % of the “services” that these environments provide to humans.
The territories of these actions had been degraded by logging, overgrazing, invasion of non-native species, soil contamination, the removal of herbivores or carnivores, or eutrophication of waters. Consequently, they have been in restorative reintroducing herbivores or carnivores, removing invasive species, planting trees and shrubs, installation of artificial reefs, the abandonment of crops, building dikes and regulators of the water cycle purification of watercourses.
They aim to restore conditions of an ecosystem before its degradation. “It’s the ideal goal,” qualifies Joseph M. Benayas, professor in the Department of Ecology at the University of Alcala de Henares and one of the authors of the study published in Science. “But in real life it is virtually impossible, so they often seek to recover part of the ecosystem, or an attribute value, eg the beauty of a river that runs through town,” he explains.
However, how these projects can reverse environmental degradation? Reply to this question has been the goal of this first assessment, systematic and quantitative success of ecological restoration, “says Benayas. His team analyzed the results of 89 actions in a representative range of terrestrial and aquatic ecosystems, ranging from the pine forests of southeastern Spanish to mangroves in the Gulf of Guinea (Africa). Each assessment experts compared three scenarios: the degraded ecosystem, the same after its restoration and a natural environment that serves as a reference (in other words, comparing a deteriorated mangrove, mangrove restored and that a virgin mangrove).
The results were collated on the basis of 526 indicators of biodiversity parameters (numbers of bees, drones, earthworms, corals and phytoplankton, decaying leaves, soil microbes, fish richness, cover of grasses, etc.) and “services” that ecosystems yield to man (CO 2 captured, flows of clean water, timber, fertile soil ….). That process could identify and quantify the benefits outlined above.
The main message is that “restored ecosystems have recovered a good part of biodiversity loss,” explains Professor Alcala, especially in tropical environments on land. But attention: a comparison with the baseline scenario has also shown that biodiversity recovered represents 86% of the original, and services, 80%. Sufficiently illustrative figures “that humans should not consider the restoration a panacea,” he said Benayas. “We can not allow an environment degradation is always thinking that the possibility of restoration. We still need pristine ecosystems, because they are reservoirs of biodiversity. “