Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Invasive species alter habitat to their benefit

11.08.2006
When scientists study habitats that alien species have invaded, they usually find predictable patterns. The diversity of native species declines, and changes occur in natural processes such as nutrient cycling, wildfire frequency and the movement of water through the system.

But simply observing such changes doesn't prove that the invaders are responsible.

University of Michigan researchers Emily Farrer and Deborah Goldberg, however, came up with a way to tease out the cause of environmental changes in northern Michigan wetlands where invasive cattails have taken hold. The cattails, they found, alter the environment in ways that hinder native species but benefit the invaders. Farrer and Goldberg will present their results Aug. 9 at a meeting of the Ecological Society of America in Memphis, Tenn.

"When you have an invasion, you typically see three things happening at once: the invasion, the change in environment and the decrease in diversity," said Farrer, a graduate student in Goldberg's laboratory group. "But they're all happening concurrently, so you can't really tell which is causing the other." Other factors may enter in. For example, human activity, such as the use of fertilizers and road salt and the suppression of natural wildfires, also may result in environmental changes that affect species diversity.

"My question was, are humans causing the changes, or are the invaders?" Farrer said. "Finding the answer has practical implications: if you're trying to restore a natural habitat, you have to know the cause of the decline in native species. Do you target the invader or try to minimize human interference?"

Farrer began by surveying marshes in northern Michigan to find out what kinds of cattails were there. The state is home to three cattail species: the native broad-leaf cattail; the invasive narrow-leaf cattail, which was introduced on the east coast in the early 19th century and eventually found its way inland; and a hybrid of the two species that is larger than either parent and tolerates a wider range of environmental conditions.

In the marshes she studied, Farrer found that hybrids were more common than native cattails. She also noted that the areas of each marsh with lots of hybrid cattails had higher nutrient levels and heavier mats of dead cattail stems than areas with only native wetland plants. The plants growing in these invaded areas also were different, with fewer classic wetland species, such as bulrushes, rushes, and sedges, and more typical land plants like grasses, asters, and goldenrods.

Next, Farrer did transplant experiments to figure out whether the invaders were causing the changes she observed. She set up four study plots in a previously uninvaded section of marsh. In one, she transplanted live hybrid cattails; in the second she added litter---the mats of dead stems that accumulate around hybrids. A third plot received both live hybrids and litter, and the fourth was left alone.

Litter accumulation was the deciding factor, she found. "Plots with the litter treatment had higher levels of nitrogen in the soil and higher turnover rates of nitrogen, along with much lower light levels and lower soil temperatures," Farrer said. "So the litter was creating a pretty different environment."

When she tallied other plants in the experimental plots, she found that both the diversity and the density of native species were lower when litter was present. But while native plants suffered, invaders prospered. "The hybrid plants performed better with litter addition," Farrer said. "They obviously aren't hindered by the litter, and the increase in nutrients may help them grow larger."

The results suggest that invasive cattails set in motion a feedback loop that helps them gain a stronghold. "The invasive cattails change the ecosystem through litter accumulation, producing an environment in which native plants don't perform well but the invaders do," said Farrer. "As the environment changes, the cattails get more abundant and change the environment even more, resulting in even more cattails. It's interesting---and sobering---to think that it's not just humans that go out and mess up the habitat; invasive species can actually initiate that cycle."

Nancy Ross-Flanigan | EurekAlert!
Further information:
http://www.umich.edu

More articles from Ecology, The Environment and Conservation:

nachricht International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht World Water Day 2017: It doesn’t Always Have to Be Drinking Water – Using Wastewater as a Resource
17.03.2017 | ISOE - Institut für sozial-ökologische Forschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>