Islands important part of any global conservation strategy

WASHINGTON - A new study has found that rare and unique ecological communities will be lost if oceanic islands aren’t adequately considered in a global conservation plan.

Although islands tend to harbor fewer species than continental lands of similar size, plants and animals found on islands often live only there, making protection of their isolated habitats our sole chance to preserve them.

Many conservation strategies focus on regions with the greatest biodiversity, measured by counting the number of different plants and animals.

“Normally you want to focus on the most diverse places to protect a maximum number of species,” said Holger Kreft, a post-doctoral fellow at the University of California, San Diego and one of the two main authors of the study.

“But, you also want to focus on unique species which occur nowhere else,” he added.

To capture that uniqueness, Kreft and colleagues at the University of Bonn, UC San Diego and the University of Applied Sciences Eberswalde used a measure of biodiversity that weights rare species more than widespread ones.

They carved the terrestrial realm into 90 biogeographic regions, calculated biodiversity for each, then compared island and continental ecosystems.

By this measure, island populations of plants and vertebrate animals are eight to nine times as rich.

The southwest Pacific island of New Caledonia stands out as the most unique with animals like the kagu, a bird with no close relatives found only in the forested highlands that is in danger of extinction, and plants like Amborella, a small understory shrub unlike any other flowering plant that is thought to be the lone survivor of an ancient lineage.

Fragments of continents that have broken free to become islands like Madagascar and New Caledonia often serve as a final refuge for evolutionary relicts like these.

The source of diversity is different on younger archipelagos formed by volcanoes such as the Canary Islands, the Galapagos and Hawaii, which offered pristine environments where early colonizers branched out into multiple related new species to fill empty environmental niches.

The new measure doesn’t distinguish between the two sources of uniqueness, which may merit different conservation strategies.

Although islands account for less than four percent of the Earth’s land area, they harbor nearly a quarter of the world’s plants, more than 70,000 species that don’t occur on the mainlands.

Vertebrate land animals - birds, amphibians, reptiles and mammals - broadly follow this same pattern.

“Islands are important and should be part of any global conservation strategy,” Kreft said. “Such a strategy wouldn’t make any sense if you didn’t include the islands,” he added. (ANI)