Hot biodiversity point – Wikipedia

And hot biodiversity , or Biodiversity Critical Zone ^{[ first ]} , is a biogeographic, terrestrial or navy area, having a great richness of biodiversity particularly threatened by human activity.

The concept of biodiversity “hot spots” has been developed since 1988 at the University of Oxford by the Norman Myers team, a British researcher specializing in the relationships between ecology and the economy.

He observed that 44% of plant species on the planet and 35% of land vertebrate species (mammals, birds, reptiles and amphibians) were confined to 1.4% of the continent surface.
It has thus identified 25 more or less extensive sites characterized by an exceptional concentration of endemic species and a serious risk of degradation.

His work has been the subject of a publication in the scientific journal Nature the February 24, 2000 ^{[ 2 ]} .
The concept of biodiversity “hot spots” found a favorable echo with the American Nature Protection Organization Conservation International Who decided to concentrate their means in money and in priority on the conservation of these high places of biodiversity.

In 2001, this concept on the 25 natural sites to be protected, around the world, is the subject of a popular work in French by the Reader’s Digest ^{[ 3 ]} .

The definition given by International Conservation (2004) is an area which contains at least 1,500 species of endemic vascular plants and which has lost at least 70% of its primary vegetation.

With this definition, the number of hot biodiversity points has been reassessed and brought to 34 in 2004 ^{[ 4 ]} .
The “hot spots” cover 15.7% of the earth’s surface, but 88% of ecosystems having disappeared, those remaining cover only 2.3% of the land surface ^{[ 5 ]} .

Warm points are generally part of a larger ecozone: the neotropical ecozone, for example, includes central America, the Caribbean, the Chocó-Magdalena, the tropical Andes, the Cerrado, the Atlantic Forest and the tempered rainforests Valdiviennes. On the other hand, each hot spot contains several ecoregions: the Floral Kingdom of the Cape – one of the smallest – in account 3. Many regions with very rich biodiversity do not appear in this ranking because they still remain little deteriorated, the forest Amazonian is the perfect example.

Particular case: A recent study (2018) points to the importance in the context of climate change to have protected areas capable of protecting polymorphic areas in terms of mues (that is to say areas where winter forms coexist brown and white coats for species that change color depending on the season) ^{[ 6 ]} . Indeed a few species of mammals (e.g. variable hare, arctic belet and fox) and birds having a priori ” ecological functions Importantly drive by changing color depending on the season. This is a camouflage and survival issue for them ^{[ 6 ]} . For 21 species of vertebrates studied in regions under climate change: individuals die by changing color while others remain brown. The regions where seasonal hair color changes are the most variable (mues both in brown and white) could be a source of ecological resilience in the face of global warming. However, the snow room has changed significantly in the world for a few decades, which is a priori unfavorable to animals that remain white in winter where there is no more snow. Areas polymorphs are currently underrepresented among the existing protected areas, they could however be hot spots for “evolutionary rescue” in the current context of climate change ^{[ 6 ]} . THE climatic corridors allowing species that remain white in winter to go back to cold areas are also important.

Biodiversity hot spots: in green the hot spots defined from 2000 by international conservation, in blue those added later.

• Asia
  • Irano -Anatolian desert (30 – Armenia, Azerbaijan, Turkey, Georgia, Turkmenistan, Iran and Iraq)
  • Mountains of Central Asia (31 – Kazakhstan, Kyrgyzstan, Tadjikistan, Ouzbekistan, China, Afghanistan and Turkmenistan)
  • Himalayas (32 – China, India, Bhutan, Pakistan, Afghanistan)
  • Western China mountains (20)
  • Japan (33)
  • Western ghâts (21 – West of India and Sri Lanka)
  • Indo-Burma (19-Bangladesh in the far south-eastern China and northern Burma in southern Thailand)
  • Sunday (16 – Malaysian peninsula, Singapore, Brunei, Borneo, Sumatra, Java and Bali)
  • Philippines (18)
  • Wallacea (17 – Sulawesi, Petites îles de la Sonde, Moluques et Timor)

Because of its very sight, the notion of hot biodiversity was the subject of criticism ^{[ 7 ]} . Among which we find the fact that:

• Classification in hotspot is only done on a double criteria wealth/threat (wealth of total species or rich in endangered species);
• This classification is only based on the number of species of vascular plants (a high floristic diversity is often associated with high fauna and fungal diversity, but this criterion could sometimes favor plant to the detriment of animal, fungal, microbial, etc. taxa, etc. .);
• It does not take into account current and future but past changes; Thus the Congo basin is not classified hotspot , despite its immense richness, because it is still largely intact. Yet deforestation is alarming, but masked by its large area. As a result, very reduced, but today protected areas (California floristic province for example) are classified here in the same rank as regions whose environmental degradation is immense (Madagascar, Sunday, etc.).
• The consideration of smaller hot dots of biodiversity (genetic diversity in particular) is not ensured;
• A recent study has shown that where the change in land allocation was low or zero from 1500 to 2010 biodiversity was better preserved; A rapid change in land use represents an increased threat to endemic plants and is associated with the loss of the diversity of endemic plants. According to this work, other regions spared by a rapid change in land use deserves to be also classified hot biodiversity points: the mountain forests of Altai-Sayan, the Amur-Heilong river basin and subtropical forests from south-eastern China. It is also necessary to ‘ Develop specialized effective conservation strategies to alleviate the effects of rapid changes in land use on biodiversity » ^{[ 8 ]} .

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