Featured Research

from universities, journals, and other organizations

Biological Diversity: Islands Beat Mainland Nine To One

Date:
May 18, 2009
Source:
University of California - San Diego
Summary:
Rare and unique ecological communities will be lost if oceanic islands aren't adequately considered in a global conservation plan, a new study has found. 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.

Biodiversity and rarity of plants. The map with its 90 regions shows both in a combined index. It reveals that oceanic islands are particularly valuable. Among the mainland areas with the highest values are tropical mountains and regions with a Mediterranean climate.
Credit: Image courtesy of University of California - San Diego

Rare and unique ecological communities will be lost if oceanic islands aren't adequately considered in a global conservation plan, a new study has found. 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."

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 Galαpagos 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."

Threats to biodiversity may also rise faster for islands than for mainlands, the team reports. Scenarios based on a measure of human impact projected to the year 2100 warn that life on islands will be more drastically affected than mainland populations.

"That threat is expected to accelerate particularly rapidly on islands where access to remaining undeveloped lands is comparatively easy" said Gerold Kier, project leader at the University of Bonn and lead author of the study. Expanding farmlands, deforestation, and other changes in how people use land are among the alterations expected to cause the greatest damage.

The researchers also considered future challenges posed by climate change and report mixed impacts. Rising sea levels will swamp low-lying areas and smaller islands, but the ocean itself is expected to moderate island climates by buffering temperature changes. "Although disruptions to island ecosystems are expected to be less severe than on the continents, climate change remains one of the main threats to the biodiversity of the Earth," Kier said. "If we cannot slow it down significantly, protected areas will not be much help."

"We now have new and important data in our hands, but still have no simple solutions for nature conservation," Kreft said. "In particular, we need to answer the question how protected areas with their flora and fauna can complement each other in the best way. The part played by ecosystems, for example their ability to take up the green-house gas carbon dioxide, should be increasingly taken into account."

Co-authors included Tien Ming Lee and Walter Jetz of UC San Diego; Pierre Ibisch and Christoph Nowicki of the University of Applied Sciences Eberswalde; and Jens Mutke and Wilhelm Barthlott of the University of Bonn.

The Academy of Sciences and Literature Mainz, the Wilhelm Lauer Foundation, and the German Federal Ministry of Education and Research funded the research. Holger Kreft holds a Feodor-Lynen Fellowship from the Alexander von Humboldt Foundation.


Story Source:

The above story is based on materials provided by University of California - San Diego. Note: Materials may be edited for content and length.


Journal Reference:

  1. Gerold Kier, Holger Kreft, Tien Ming Lee, Walter Jetz, Pierre L. Ibisch, Christoph Nowicki, Jens Mutke & Wilhelm Barthlott. A global assessment of endemism and species richness across island and mainland regions. Proceedings of the National Academy of Sciences, May 11, 2009 DOI: 10.1073/pnas.0810306106

Cite This Page:

University of California - San Diego. "Biological Diversity: Islands Beat Mainland Nine To One." ScienceDaily. ScienceDaily, 18 May 2009. <www.sciencedaily.com/releases/2009/05/090511180651.htm>.
University of California - San Diego. (2009, May 18). Biological Diversity: Islands Beat Mainland Nine To One. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2009/05/090511180651.htm
University of California - San Diego. "Biological Diversity: Islands Beat Mainland Nine To One." ScienceDaily. www.sciencedaily.com/releases/2009/05/090511180651.htm (accessed July 22, 2014).

Share This




More Plants & Animals News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Michigan Plant's Goal: Flower and Die

Michigan Plant's Goal: Flower and Die

AP (July 22, 2014) — An 80-year-old agave plant, which is blooming for the first and only time at a University of Michigan conservatory, will die when it's done (July 22) Video provided by AP
Powered by NewsLook.com
San Diego Zoo Welcomes New, Rare Rhino Calf

San Diego Zoo Welcomes New, Rare Rhino Calf

Reuters - US Online Video (July 21, 2014) — An endangered black rhino baby is the newest resident at the San Diego Zoo. Sasha Salama reports. Video provided by Reuters
Powered by NewsLook.com
Shark Sightings a Big Catch for Cape Tourism

Shark Sightings a Big Catch for Cape Tourism

AP (July 21, 2014) — A rise in shark sightings along the shores of Chatham, Massachusetts is driving a surge of eager vacationers to the beach town looking to catch a glimpse of a great white. (July 21) Video provided by AP
Powered by NewsLook.com
$23.6 Billion Awarded To Widow In Smoking Lawsuit

$23.6 Billion Awarded To Widow In Smoking Lawsuit

Newsy (July 20, 2014) — Cynthia Robinson claims R.J. Reynolds Tobacco Company hid the health and addiction risks of its products, leading to the death of her husband in 1996. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins