A biodiversity hotspot is a biogeographic region that is a significant reservoir of life and is also under threat from human activities. These areas are characterized by exceptional concentrations of species, many of which are found nowhere else on the planet. The idea was introduced to help prioritize conservation efforts, focusing resources on areas where the potential for species loss is greatest.
Criteria for Designation
A region must meet two strict criteria to be formally designated as a biodiversity hotspot. The first is that it must contain at least 1,500 species of vascular plants as endemics. This figure represents more than 0.5% of the world’s total plant species, signifying a unique and dense concentration of life that exists nowhere else.
The second criterion measures the region’s vulnerability. A hotspot must have lost at least 70% of its original primary vegetation. This high degree of habitat loss indicates that the unique species within the region are under severe threat, pinpointing areas where conservation can be most impactful.
This dual-criteria system was developed by scientist Norman Myers in 1988 and later refined in 2000. The goal was to create a systematic way to identify the planet’s most threatened centers of life. Currently, 36 regions around the globe meet these requirements, making them focal points for global conservation organizations.
Where Are Biodiversity Hotspots Found?
Biodiversity hotspots are distributed across the globe but are particularly concentrated in tropical regions and on islands. These 36 designated areas cover just 2.4% of Earth’s land surface, yet they support nearly 60% of the world’s plant, bird, mammal, reptile, and amphibian species. Their locations often coincide with areas that have complex geology and have experienced periods of climatic stability, allowing for the evolution of a wide array of species.
One prominent example is the California Floristic Province, which stretches along the Pacific coast of North America. This region’s unique Mediterranean climate supports a diversity of flora, including iconic species like the Giant Sequoia. It is home to more than 3,400 native plant species, over 60% of which are endemic.
Another globally recognized hotspot is Madagascar and the surrounding Indian Ocean Islands. Isolation has driven the evolution of a unique assemblage of wildlife, with over 90% of its species found nowhere else on Earth. The island is famous for its many species of lemurs, a primate group entirely endemic to the region.
The Tropical Andes, stretching through South America, is considered the world’s most diverse hotspot. This mountainous region hosts an estimated 30,000 vascular plant species, with about half of them being endemic. Its varied elevations create a multitude of microclimates, each supporting its own distinct community of plants and animals.
The Role of Endemic Species
Endemism refers to a species being unique to a defined geographic location, such as an island or nation. A high concentration of these geographically restricted species is what makes a biodiversity hotspot so irreplaceable. The fate of these species is directly tied to the health of their limited habitat.
When a region rich in endemic species suffers habitat destruction, the species living there face the risk of global extinction. This is because they have no other populations elsewhere in the world to draw from. If their only home is destroyed, they are gone forever, which elevates the conservation importance of hotspots.
In contrast, other ecosystems might have a high number of total species, but these species may be widespread. While the loss of such a habitat is still a negative event, the species themselves are less likely to face complete extinction. The focus on endemism within the hotspot criteria, therefore, directs conservation funding toward preventing the permanent loss of unique life forms.
Threats to Biodiversity Hotspots
The primary threat to biodiversity hotspots is habitat destruction, which is largely caused by human activities. The expansion of agriculture, logging operations, and the spread of urban areas all contribute to the fragmentation and elimination of natural environments.
Climate change presents another significant pressure on these sensitive areas. As global temperatures and weather patterns shift, habitats can become unsuitable for the species that have evolved there. Their ability to migrate is often limited by geographical barriers or the fragmented nature of the remaining habitat.
The introduction of invasive species poses a further danger to the native inhabitants of hotspots. Non-native plants and animals, often introduced by humans, can outcompete endemic species for resources or introduce new diseases. These invaders can disrupt ecological balances and drive endemic species toward extinction.