Biodiversity Hotspots: What They Are and Why They Matter

In 1988, ecologist Norman Myers published a paper in Nature that would reshape conservation strategy for decades: an analysis of where threatened endemic plant species coincided with rapid habitat destruction. Myers identified ten tropical forest "hotspots" — areas where extraordinary biological uniqueness and extreme conservation urgency overlapped. The concept, expanded and formalised by Conservation International, now underpins a global conservation framework of 36 hotspots that guides billions of dollars of annual protection spending.

The Two Qualifying Criteria

A region qualifies as a biodiversity hotspot only if it meets both of the following thresholds simultaneously:

1. At least 1,500 endemic vascular plant species — species of flowering plants, conifers, ferns, and related groups that are found only in that region and nowhere else on Earth. The 1,500-species threshold is demanding: the entire British Isles contains fewer than 1,600 native vascular plant species, with virtually none endemic to Britain alone.
2. Loss of at least 70% of original primary vegetation — the region must already be severely degraded. This ensures that hotspots are not merely diverse, but also urgently threatened. A pristine, intact biome with 2,000 endemic species would not qualify if it retains 90% of its original habitat.

The dual-criterion approach targets conservation investment at areas offering the highest return: regions that are both irreplaceable (unique endemic species that cannot be conserved anywhere else) and critical (habitat so degraded that further delay in protection risks permanent loss).

Scale and Coverage

Together, the 36 recognised hotspots covered approximately 35.5 million km² in their original extent — roughly 23.5% of Earth's land surface. Due to the 70%-loss-of-habitat criterion, intact primary vegetation now remains on only about 2.5% of Earth's land. Yet within these diminished remnants, biodiversity is extraordinary:

• More than 150,000 endemic vascular plant species — approximately 50% of all plant species on Earth
• More than 43% of all bird, mammal, reptile, and amphibian species, as endemics
• Approximately 35% of all vertebrate species

This disproportionate concentration of endemic life in a small fraction of Earth's land surface provides the conservation logic for hotspot prioritisation: protecting and restoring these areas safeguards more of the irreplaceable fraction of biodiversity per hectare than protecting any equivalent area elsewhere.

Selected Hotspot Profiles

The Tropical Andes

Stretching from Venezuela through Colombia, Ecuador, Peru, and Bolivia to northern Argentina, the Tropical Andes is widely regarded as the most biologically diverse terrestrial region on Earth. Altitude creates an extraordinary range of climatic zones — from lowland Amazon rainforest to high-altitude puna grassland and glacial páramo — in compressed horizontal distance, generating exceptional beta diversity. The hotspot contains approximately 15,000 endemic vascular plant species, 600 endemic birds, and more endemic amphibian species than any other hotspot. Around 75% of its original habitat has been lost to agriculture, livestock grazing, and urban expansion.

Sundaland

Sundaland encompasses the western portion of the Malay Archipelago — the Malay Peninsula, Borneo, Sumatra, Java, and associated islands. During glacial periods, much of this region was dry land, allowing species to disperse across what are now sea channels. Today it harbours approximately 15,000 endemic plant species and is one of the last refuges for Sumatran orangutans, Bornean pygmy elephants, and Sumatran rhinos. Deforestation for palm oil, pulpwood, and smallholder agriculture has reduced intact forest to approximately 7% of the original cover.

Madagascar and the Indian Ocean Islands

Madagascar separated from Africa approximately 88 million years ago, creating a natural laboratory for evolution in isolation. More than 90% of its reptile species, 83% of its mammals, and approximately 80% of its plants are endemic. The island's lemurs — over 100 species — are found nowhere else. Slash-and-burn agriculture and charcoal production have destroyed roughly 90% of Madagascar's original forest cover, making it one of the most acute conservation crises globally.

The Mediterranean Basin

Europe's only biodiversity hotspot spans the lands bordering the Mediterranean Sea — from Portugal and Morocco to Turkey and the Levant. It contains approximately 13,000 endemic plant species, many concentrated in the evergreen shrubland (maquis/garrigue) ecosystems characteristic of the climate. Urbanisation, tourism infrastructure, agricultural intensification, and increasingly severe wildfire regimes driven by drought have degraded or destroyed more than 70% of the original natural vegetation.

The Cape Floristic Region

Located at the southern tip of Africa, the Cape Floristic Region is the smallest of the recognised hotspots yet arguably the most species-dense. It contains approximately 6,210 endemic plant species in an area of only 90,000 km² — a species richness comparable to entire continental regions. The fynbos biome, characterised by hard-leaved shrubs and spectacular diversity of the Proteaceae and Restionaceae families, is found nowhere else. Wine and wheat agriculture, invasive Australian acacias and pines, and altered fire regimes are the primary threats.

Threats Within Hotspots

The fact that hotspots are defined in part by historical habitat loss means that ongoing threats are particularly acute. Agricultural expansion — the primary driver globally — is especially damaging in tropical hotspots where remaining forest fragments are small, isolated, and surrounded by agricultural land. Climate change is altering precipitation regimes, fire frequencies, and species distributions in ways that interact poorly with already-fragmented habitats. Invasive species and overexploitation compound these pressures in many hotspot regions.

Conservation Investment and Outcomes

The Critical Ecosystem Partnership Fund (CEPF), co-managed by Conservation International, the World Bank, and several other partners, is the principal multilateral funding mechanism for hotspot conservation. Since its founding in 2000, CEPF has invested over USD 900 million in more than 6,700 projects across 25 hotspots. Successful outcomes include the recovery of several large mammal populations where poaching has been reduced, the restoration of degraded habitat linking isolated forest fragments, and the discovery of hundreds of new species in poorly surveyed hotspot regions each year — reinforcing that biological inventories in hotspots remain incomplete.

Frequently Asked Questions