Biodiversity is not spread uniformly across the planet. Certain geographic areas contain an exceptionally high concentration of unique plant and animal species, making them irreplaceable reservoirs of life. These zones, designated as biodiversity hotspots, are scientifically defined regions recognized for their biological value and the significant threats they face. The concept focuses conservation efforts on these relatively small areas to guide international strategies aimed at preserving global species diversity.
Criteria for Hotspot Designation
A region must meet two scientific criteria to be formally recognized as a biodiversity hotspot. The first criterion is based on species richness and uniqueness, demanding a high degree of endemism. An area must contain at least 1,500 species of vascular plants found nowhere else on Earth, representing more than 0.5% of the global total. This ensures the region holds a unique collection of flora.
The second criterion addresses the severity of the threat facing native ecosystems. To qualify, the area must have lost 70% or more of its original primary native vegetation, meaning only 30% or less of the original habitat remains intact.
Global Concentration of Critical Hotspots
There are currently 36 recognized biodiversity hotspots distributed across the globe, with the majority concentrated in tropical and Mediterranean-type climates. These regions collectively cover only about 2.4% of the Earth’s land surface, yet they house nearly 60% of the world’s plant, bird, mammal, reptile, and amphibian species.
In the Americas, a significant concentration of hotspots lies in Central and South America. The Tropical Andes, stretching along the western edge of South America, is considered the most species-rich hotspot globally, containing nearly one-sixth of the world’s plant species. The Atlantic Forest in Brazil, extending into Paraguay and Argentina, is another extensive region known for its high number of endemic tree species and primates. North America contains the California Floristic Province, which is notable for its unique mix of Mediterranean-type climate vegetation, including the iconic giant sequoia and coastal redwood trees.
Asia and Oceania host a large number of island and archipelago hotspots, which often show intense levels of endemism due to long periods of isolation. The Sundaland hotspot, which includes the islands of Borneo and Sumatra in Southeast Asia, is a major center for tropical rainforest biodiversity, housing species like the orangutan and Sumatran rhinoceros. Wallacea, an area comprising Indonesian islands not connected to the Asian or Australian continental shelves, is characterized by a unique mix of species with evolutionary links to both continents. The Philippines, an archipelago with over 7,000 islands, is recognized for its exceptionally high rates of reptile and amphibian endemism.
Africa and the Middle East are home to several distinct hotspots, including the Cape Floristic Region in South Africa. This small area contains over 9,000 plant species, with 69% found nowhere else. Madagascar and the Indian Ocean Islands are a separate hotspot isolated for millions of years, resulting in a staggering 85% endemism rate for its animals and 90% for its plants, including all lemur species. The Mediterranean Basin is a unique hotspot spanning multiple continents, characterized by shrublands and forests adapted to dry summers and mild, wet winters.
Significance of Hotspot Conservation
Focusing conservation efforts on biodiversity hotspots maximizes the impact of limited resources. By targeting areas where high species density and high threat levels overlap, conservationists protect the greatest number of unique species per unit of area. The concentration of endemic life means their loss would result in a disproportionate reduction in global species diversity.
The preservation of these hotspots also maintains global ecosystem stability. These areas provide essential ecosystem services, such as regulating regional climate, purifying water supplies, and sequestering carbon dioxide. The forests within these hotspots act as carbon sinks, helping to mitigate global climate change.
Protecting these small geographic areas is considered one of the most effective strategies for preventing a mass extinction event. The health of these ecosystems underpins the survival of thousands of species and supports many natural processes vital to human life.