Habitat Loss and Extinction in the Hotspots of Biodiversity

Abstract

Nearly half the world's vascular plant species and one‐third of terrestrial vertebrates are endemic to 25 “hotspots” of biodiversity, each of which has at least 1500 endemic plant species. None of these hotspots have more than one‐third of their pristine habitat remaining. Historically, they covered 12% of the land's surface, but today their intact habitat covers only 1.4% of the land. As a result of this habitat loss, we expect many of the hotspot endemics to have either become extinct or—because much of the habitat loss is recent—to be threatened with extinction. We used World Conservation Union [ IUCN ] Red Lists to test this expectation. Overall, between one‐half and two‐thirds of all threatened plants and 57% of all threatened terrestrial vertebrates are hotspot endemics. For birds and mammals, in general, predictions of extinction in the hotspots based on habitat loss match numbers of species independently judged extinct or threatened. In two classes of hotspots the match is not as close. On oceanic islands, habitat loss underestimates extinction because introduced species have driven extinctions beyond those caused by habitat loss on these islands. In large hotspots, conversely, habitat loss overestimates extinction, suggesting scale dependence (this effect is also apparent for plants). For reptiles, amphibians, and plants, many fewer hotspot endemics are considered threatened or extinct than we would expect based on habitat loss. This mismatch is small in temperate hotspots, however, suggesting that many threatened endemic species in the poorly known tropical hotspots have yet to be included on the IUCN Red Lists. We then asked in which hotspots the consequences of further habitat loss (either absolute or given current rates of deforestation) would be most serious. Our results suggest that the Eastern Arc and Coastal Forests of Tanzania‐Kenya, Philippines, and Polynesia‐Micronesia can least afford to lose more habitat and that, if current deforestation rates continue, the Caribbean, Tropical Andes, Philippines, Mesoamerica, Sundaland, Indo‐Burma, Madagascar, and Chocó–Darién–Western Ecuador will lose the most species in the near future. Without urgent conservation intervention, we face mass extinctions in the hotspots.

Diversity, distribution, and conservation of endemic island rodents

“…However, it is evident that most of the arboreal/scansorial species of endemic insular genera are today restricted to areas where the rate of the deforestation is rapidly progressing (e.g. Brooks et al, 1997Brooks et al, , 1999Brooks et al, , 2002, such that further losses are to be expected without urgent conservation attention. We highlight a particularly interesting category of rodents of grave conservation concern: those that must now classified as ''pseudo-endemic'' to islands.…”

Responses of Soil Fungi to Logging and Oil Palm Agriculture in Southeast Asian Tropical Forests

“…Tropical forests contain more than two-thirds of all terrestrial plant and animal species [1][2][3], but long-term prospects for their survival are uncertain, as more than half of the original extent of these forests has already been degraded by human land-use change and other perturbations [4]. Agricultural expansion continues to be the main driver of tropical deforestation [5] with more than one third of the global terrestrial land area currently under cultivation [6].…”

Global climate cycles and cyclones: consequences for rainfall patterns and lemur reproduction in southeastern Madagascar

“…More than half of these hotspots consist of tropical rainforest and we know very little about how global climate change is likely to affect the ecosystems and threatened wildlife within by these areas (Brooks et al, 2002). This is especially concerning since tropical rainforest is now limited to only 1.4% of the Earth's landmass.…”