Acting for biodiversity
France has just over 130 so-called natural habitats, such as hay meadows, marshes, cliffs, caves and oak groves. In their current state, only 22% of these areas are in a prosperous state. Conversely, 35% are likely to disappear. As a result, 26% of these areas are threatened in France, including many endemic (local) species. Specialist birds, which live in targeted areas such as forests or cities and therefore have stricter requirements in terms of natural needs, are an excellent marker of the state of different areas. Forest birds have declined by about 3% since 1987 and agricultural birds have declined by about 30%. However, while the endemic species are disappearing, they are giving way to more generalist species. Thus, birds living in all types of habitats, such as pigeons, have seen their population increase by 19%. More than a disappearance, we are witnessing a replacement of animal populations. The least well-preserved areas in France are the wetlands and coastal areas, even though it has the second largest maritime domain in the world. Coral reefs are also one of the richest ecosystems, and their population is declining by 29%. This decline could lead to a delay in the reproduction and growth of species.aquatiques.
If the degradation of the state of fresh water is to be attributed to Man and the pressure he exerts on these ecosystems (pollution, overexploitation...) and corals are disappearing because of mass tourism and global warming, they are also threatened by natural phenomena such as cyclones, starfish or algae. Another major cause, and probably the most important one concerning the impoverishment of biodiversity in France, is the introduction of invasive alien species into its landscape. The coypu or the Asian hornet, for example, are species that have been introduced voluntarily or involuntarily and are the cause of many irreversible damages to our local biodiversity, thus upsetting the ecosystem balance.
Laurent Godet, a CNRS researcher interviewed by National Geographic, completes this statement by using birds as indicators. "On a global scale, the disappearance of all bird species and subspecies on Earth since 1500 can be directly or indirectly attributed to humans. Immediately after the introduction of exotic species, the second most important cause of bird extinction is hunting." While the Council of State has just validated the maintenance of glue hunting in certain French regions, one could say that nothing is being done to improve the situation.
However, actions are carried out by the authorities and various organisations and the results in terms of regulating and monitoring biodiversity are sometimes visible. Laurent Godet told us that "the best way to "regulate" populations is to conserve their predators. "In France, certain predators play a major role in this regulation, notably the brown bear and the grey wolf. In this sense, and although these species have seen their habitat area reduced, the distribution of their territory is regularly monitored and they are the subject of various reintroduction plans and the establishment of protected areas. Another positive point is that French surface waters have improved by 0.8% in recent years in terms of quality, thanks to measures taken by the State and local authorities to preserve and restore them.
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We are not in the right direction, it is time to react and really take things in hand" says Véronique Andrieux, Director General of WWF France on the occasion of the release of the Living Planet 2020 Report. Since 1998, the NGO WWF has published a report every two years that measures the state of the planet's biodiversity and this year the balance sheet has never been so bad.
In fact, different regions of the world are not impacted in the same way the 94% drop in the Living Planet Index for the tropical sub-regions of the Americas is the largest decline ever observed " can we read in the report. The causes? We know them, the destruction of natural environments that gives way to intensive industrial livestock farming models and agricultural production that generate 80% of global deforestation. The over-exploitation of marine environments, which leads to the destruction of ecosystems, plastic or chemical pollution, the accidental introduction of species... The causes are too numerous.
The Director General of WWF is still hopeful, however, "when you make efforts in terms of conservation, it works! "she rejoices.
Indeed, researchers sometimes observe in some species that the number of individuals is increasing, this is the case of the otter (Lutra lutra), the lynx (Lynx lynx) or the salmon (Oncorhychus kisutch) in France. The otter had almost disappeared in France at the end of the 1980s, but thanks to a national otter action plan, otter populations are increasing and now this species is present in half of the French departments! This is very good news for this species which is a very good bio-indicator" she continues. "When we talk about biodiversity, we also talk about humans, and protecting nature means protecting humans! "she continues.
According to the Living Planet Index, calculated by the Zoological Society of London, the average size of wild vertebrate populations has declined by 68%. In other words, in less than half a century, the numbers of more than 20,811 populations of 4,392 species of mammals, birds, amphibians, reptiles and fish have fallen by two-thirds.
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Marine biodiversity observation programmes today cover a very small area of the oceans and most often take place in regions close to the coasts. It is therefore difficult to determine the evolution of this biodiversity present in the water that covers 70% of our planet's surface. Yet this is what an international team of researchers, led by scientists from the CNRS, has achieved.
They developed a mathematical and computer programme which, once integrated into the powerful calculator at the CNRS Oceanology and Geoscience Laboratory, enabled the researchers "to quantify the strength and spatial extent of these biological changes. They have highlighted a recent and unprecedented increase in "climatic surprises", probably attributable to the El Niño phenomenon, to thermal anomalies in the Atlantic and Pacific Oceans and to Arctic warming" reveals a press release published by the CNRS.
Marine biodiversity is estimated at just over two million species, but the scientific community has so far described only 200,000, or "only" 10%. Moreover, little is known about their biology. To make up for this lack of data, Grégory Beaugrand, director of research at the CNRS Oceanology and Geosciences Laboratory, and his team have imagined fictitious and theoretical species that meet the known fundamental biological principles "that govern the organisation of species and biodiversity".
These species have been developed at the Laboratoire d'Océanilogie et de Géoscience since 2008 and have laid the foundations for this model. "We have estimated the sensitivity of all marine species to climate change by studying the responses of these theoretical communities to a homogeneous increase in temperature. By proceeding in this way] it is then possible to relate, for a given region, the sensitivity of communities to their intrinsic properties," explains Grégory Beaugrand.
This model makes it possible to identify and quantify the regions potentially involved in these evolutions, to understand the biological mechanisms responsible for these evolutionary phenomena and to anticipate them. "Our model anticipates biological changes one year before they occur. We therefore draw attention to these phenomena, which often have major socio-economic consequences," adds Grégory Beaugrand.
To put the detected changes into perspective, the model is based on an observation of changes that took place in the distant past, such as at the last glacial maximum 20,000 years ago or in the middle Pliocene 3.3 million years ago.
Between the last glacial maximum and the present day, the earth's landscape has changed dramatically. The average global temperature was 5° C lower than today, sea level was 125 metres lower and the concentration of CO2 was close to 170 ppm (part per million), a far cry from the 411 ppm currently recorded at Mauna Loa, which is the site with the longest monitoring of atmospheric CO2," explains the researcher, before adding: "The average Pliocene is considered to have experienced thermal conditions very close to those projected for the end of this century. The average global temperature was 2 to 3°C higher than today and the atmospheric CO2 concentration was close to that observed today ".
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