A biodiversity hotspot is a region of the Earth that is extremely biologically diverse and also under severe threat due to habitat loss, climate change, or extensive species loss. Around 25 sites worldwide are recognized as such hotspots, and several organizations have made efforts to protect these sites. Guarding these regions from further damage is considered environmentally and culturally important, as they host organisms that are not found anywhere else on Earth.
There is some argument about how to define a biodiversity hotspot, with many definitions focusing heavily on vascular plants, sometimes at the expense of other living organisms. As a general rule, in order for a region to be included in this category, it must be biologically diverse, with a high proportion of species that are not found anywhere else on Earth, and the security of the region must be threatened. Losing more than 70% of native vegetation, for example, is a clear example of a threat.
These regions can be found all over the world, and they vary considerably in size and composition. The California Floristic Province, for example, extends along the West Coast of North America, and covers both land and water, encompassing the rich ocean life off the coast along with the diverse plant and animal species found in California, Oregon, and Northern Mexico. The Succulent Karoo in Africa, on the other hand, covers a relatively small and extremely arid region, in marked contrast to the lush environments of sites like the Atlantic Forest in South America and the countries of New Zealand and Japan, both of which are considered biodiversity hotspots.
These regions contain around 60% of all of the species found on Earth, and because these species are endemic, damage to the regions could cause significant problems. Biodiversity as a whole on the Earth would decline, because many animals would vanish forever if their native habitats were severely compromised. In addition to being simply unfortunate, a decline in biodiversity could mean that humans might lose access to medically important plant species, among many other things.
Some hotspots have been protected through legislation or the acquisition of threatened regions by conservation organizations. Greater protection is needed for most of these regions, however, and some researchers would like to see the definition expanded to cover more areas in danger. The human populations that live near biodiversity hotspots also have a vested interest in the survival of these unique regions of the Earth, since many communities make their living from the diverse plant and animal life in such areas.