Featured Research

from universities, journals, and other organizations

Invading Trees Put Rainforests At Risk

Date:
March 6, 2008
Source:
Carnegie Institution
Summary:
To the list of threats to tropical rainforests you can add a new one -- trees. It might seem that for a rainforest the more trees the merrier, but a new study warns that non-native trees invading a rainforest can change its basic ecological structure -- rendering it less hospitable to the myriad plant and animal species that depend on its resources.

3-D Imaging of invasive tree species (reds-pinks) and native Hawaiian lowland rainforest (greens).
Credit: Gregory Asner

To the list of threats to tropical rainforests you can add a new one -- trees. It might seem that for a rainforest the more trees the merrier, but a new study by scientists at the Carnegie Institution warns that non-native trees invading a rainforest can change its basic ecological structure -- rendering it less hospitable to the myriad plant and animal species that depend on its resources. Results are published in the Proceedings of the National Academy of Sciences.*

Related Articles


The research team, led by Gregory Asner of the Carnegie Institution's Department of Global Ecology, used innovative remote sensing technology on aircraft to survey the impact of invasives on more than 220,000 hectares (850 square miles) of rainforest on the island of Hawaii. Previous studies of the impact of invasive plants on forests were limited to small areas. Instruments aboard the Carnegie Airborne Observatory (CAO) penetrate the forest canopy to create a regional "CAT scan" of the ecosystem, identifying key plant species and mapping the forest's three-dimensional structure.

"Invasive tree species often show biochemical, physiological, and structural properties that are different from native species," says Asner. "We can use these 'fingerprints' combined with the 3-D images to see how the invasives are changing the forest."

This is the first use of this approach to track invasives in Hawaii, where roughly half of all organisms are non-native, and approximately 120 plant species are considered highly invasive. Undisturbed Hawaiian rainforests are often dominated by the ohia tree (Metrosideros polymorpha), but these slow-growing native trees are losing ground to newcomers, such as the tropical ash (Fraxinus uhdei) and the Canary Island fire tree (Morella faya).

CAO surveys of rainforest tracts on the Mauna Kea and Kilauea Volcanoes found that stands of these two invasive tree species form significantly denser canopies than the native ohia trees. Less light reaches lower forest levels, and as a result native understory plants such as tree ferns are suppressed.

Introduced trees can also pave the way for more invaders by altering soil fertility. The Moluccan albizia (Falcataria moluccana) "fixes" atmospheric nitrogen, concentrating it in the soil, which speeds the growth of a smaller invasive tree, the Strawberry Guava (Psidium cattleianum). The guava trees form a dense, mid-level thicket that blocks most light from reaching the ground and stifles young native plants.

"All of our invasive species detections were made in protected state and federal rainforest reserves," says Asner. "These species can spread across protected areas without the help of land use changes or other human activities, suggesting that traditional conservation approaches on the ground aren't enough for the long-term survival of Hawaii's rainforests."

"These new airborne technologies, which are sensitive enough to discern saplings and young trees, may make the problem more tractable,"comments study co-author Flint Hughes of the US Forest Service. "They allow scientists to probe the make-up of forests over large areas and detect invasions at earlier stages."

Based on the success of this study, Asner and colleagues plan to expand CAO surveys of the ecological impacts of invaders in other forests on Hawaii and Kauai Islands, where premier, remote rainforest reserves remain virtually unmapped.

The Carnegie Airborne Observatory is made possible by the support of the W.M. Keck Foundation and William Hearst III.

* Authors: Gregory P. Asner, R. Flint Hughes, Peter M. Vitousek, David E. Knapp, Ty Kennedy-Bowdoin, Joseph Boardman, Roberta E. Martin, Michael Eastwood, and Robert O. Green


Story Source:

The above story is based on materials provided by Carnegie Institution. Note: Materials may be edited for content and length.


Cite This Page:

Carnegie Institution. "Invading Trees Put Rainforests At Risk." ScienceDaily. ScienceDaily, 6 March 2008. <www.sciencedaily.com/releases/2008/03/080303190645.htm>.
Carnegie Institution. (2008, March 6). Invading Trees Put Rainforests At Risk. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2008/03/080303190645.htm
Carnegie Institution. "Invading Trees Put Rainforests At Risk." ScienceDaily. www.sciencedaily.com/releases/2008/03/080303190645.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) — Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Blu-Ray Discs Getting Second Run As Solar Panels

Blu-Ray Discs Getting Second Run As Solar Panels

Newsy (Nov. 26, 2014) — Researchers at Northwestern University are repurposing Blu-ray movies for better solar panel technology thanks to the discs' internal structures. Video provided by Newsy
Powered by NewsLook.com
Antarctic Sea Ice Mystery Thickens... Literally

Antarctic Sea Ice Mystery Thickens... Literally

Newsy (Nov. 25, 2014) — Antarctic sea ice isn't only expanding, it's thicker than previously thought, and scientists aren't sure exactly why. Video provided by Newsy
Powered by NewsLook.com
3D Map of Antarctic Sea Ice to Shed Light on Climate Change

3D Map of Antarctic Sea Ice to Shed Light on Climate Change

Reuters - Innovations Video Online (Nov. 24, 2014) — A multinational group of scientists have released the first ever detailed, high-resolution 3-D maps of Antarctic sea ice. Using an underwater robot equipped with sonar, the researchers mapped the underside of a massive area of sea ice to gauge the impact of climate change. Ben Gruber reports. Video provided by Reuters
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:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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