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.*

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 July 23, 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 July 23, 2014).

Share This




More Earth & Climate News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

New Orleans Plans to Recycle Cigarette Butts

New Orleans Plans to Recycle Cigarette Butts

AP (July 21, 2014) New Orleans is the first U.S. city to participate in a large-scale recycling effort for cigarette butts. The city is rolling out dozens of containers for smokers to use when they discard their butts. (July 21) Video provided by AP
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
Spectacular Lightning Storm Hits London

Spectacular Lightning Storm Hits London

AFP (July 19, 2014) A spectaCular lightning storm struck the UK overnight Friday. Images of lightning strikes over the Shard and Tower Bridge in central London. Duration: 00:23 Video provided by AFP
Powered by NewsLook.com
A Centuries' Old British Tradition Is Far from a Swan Song

A Centuries' Old British Tradition Is Far from a Swan Song

AFP (July 19, 2014) As if it weren't enough that the Queen is the Sovereign of the UK and 15 other Commonwealth realms, she is also the owner of all Britain's unmarked swans. Duration: 02:18 Video provided by AFP
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