A territory with an area equivalent to that of the State of Minas Gerais in which 82% of plant species and 90% of vertebrates only occur there. Living with this unique biodiversity on the planet, a population with one of the lowest human development indexes (HDI) in the world. Madagascar, an island country on the south-east African coast, has the challenge of harmonizing conservation with development.

A picture of this biological diversity, the main threats and perspectives for its conservation make up two studies published in the journal Science on Thursday (01/12) by researchers from 50 organizations around the world, including a Brazilian one supported by FAPESP.

"From the point of view of conservation, Madagascar has similar challenges to those of Brazil. It is a developing country, but with poor remote areas. Both need to work on conservation along with improving social conditions," says Thaís Guedes, from the Institute of Biology of the State University of Campinas (IB-Unicamp), one of the authors of the studies.

In one of them, the team of researchers makes an extensive review and update of what is known about the evolution, distribution and uses of the island's biodiversity. Scientists show that madagascar species are so proper to that place that the extinction of only one of them can mean at the same time the end of an entire evolutionary lineage.

"We say that Madagascar has unique species in the world, but this goes further. There are categories larger than species that exist only there, such as lemurs [Lemuroidea], a whole order of birds [Mesitornithiformes] and all but three species of mantelid frogs. The loss of a species may represent the end of an entire lineage that took millions of years to form," guedes says.

In the case of lemurs, entire strains have already been extinct, such as those of koala lemurs, monkey lemurs and sloth lemurs. The two species of hippopotamus of the island, giant turtles, and the order of elephant birds have also disappeared from the wild. According to the researchers, extinctions like this represent large-scale implications for the functioning of the ecosystem.

The data updated by the study show that today there are described on the island 11,516 species of vascular plants (82% endemic) and 1,215 briophytes (28% exclusive to the territory). Among terrestrial and freshwater vertebrates, 95% of mammals, 56% of birds, 81% of river fish and 98% of reptiles are not found anywhere else on Earth.

13 endemic species are considered extinct, considering only extinctions after the year 1500. Another 33 extinctions occurred in prehistoric times, still associated with the arrival of the first humans on the island.

Opportunities

In the other published study, the authors reflect on the decline of Malagasy biodiversity, but also point to conservation opportunities for the country. Since a large part of the population withdraws the livelihood of forests in the form of firewood or hunting, the authors see this as an opportunity for a development based on the sustainable use of biodiversity. Of the 40,283 plant species used by humans worldwide, 1,916 (5%) are found in Madagascar, 595 endemic to the country. With 28 million inhabitants, 10.4% of the territory is protected by law.

"So far, the focus has been on creating protected areas and excluding humans from them as much as possible, reducing their impacts on biodiversity. Unfortunately, this has not brought the expected results, because poor communities – the vast majority of the country's population – need to cook and heat their homes and, without alternatives, cut trees from existing reserves to use wood," says Alexandre Antonelli, a são Paulo biologist who is scientific director of the Royal Botanic Gardens in Kew, or Kew Gardens, England.  and coordinated the studies.

Therefore, scientists suggest that the creation of new protected areas should not be the focus, but rather restore forests outside these territories to lessen the pressure on them. Reforestation and conservation, based on scientific evidence and effectiveness, are some of the five opportunities that the authors list for the country. To come up with suggestions, scientists debated with researchers inside and outside Madagascar, as well as conservation and political leaders.

The authors also suggest expanding biodiversity monitoring, including the production and availability of databases on species. In addition, they reinforce the need to increase the effectiveness of the protection of existing areas, either by community engagement, training and income generation opportunities. For this, conservation and restoration initiatives should also include landscapes and communities surrounding the protected areas. Finally, actions to conserve forests must take into account the main causes of biodiversity loss, which includes poverty and food insecurity, problems that also affect Brazil, despite the peculiarities of each country.

"It is of enormous national and global interest that forests in both countries be preserved and degraded areas restored. They capture and store large amounts of carbon, which is essential to combatglobal warming. When they are cut, the consequences affect the most marginalized populations in society," antonelli explains. 

The scientist lists among the problems arising from deforestation the lack of drinking water in streams and groundwater, higher risk of landslides on mountain slopes, lower number of pollinating insects for agriculture near forests and less possibility for human communities to face extreme heat waves, due to lack of shade and cooling factor provided by the evaporation of water from forests.

"In general, the patterns of biodiversity richness that we present to Madagascar are very much shaped by the knowledge of plants and vertebrates. We don't know very well invertebrates and fungi, for example. We need to showcase these little-known groups, as well as employ multiple diversity metrics in future studies. We recommend, both for Madagascar and Brazil, to take into account not only the diversity of species but also the evolutionary history of these places", concludes Guedes.

The study Madagascar's extraordinary biodiversity: Threats and opportunities is available to subscribers here.