Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fertilization by invasive species threatens nutrient-poor ecosystems

13.03.2012
Biologists at Bielefeld University have developed a new method for quantifying the effect of non-native species on ecosystem functioning

Invasive species are prolific non-native plants or animals that, when introduced to an ecosystem, may imbalance the system and disrupt its natural functioning. Biologists at Bielefeld University in the team of Junior Professor Dr. Christiane Werner in cooperation with the University of Lisbon have developed non-invasive method for quantifying the spatial impact of such exotic species on the ecosystems which they invade.

They can estimate whether native plants in the neighbourhood of invasive species incorporate the nitrogen fixed by the latter. The biologists examined the Sydney Golden Wattle (Acacia longifolia), an Australian shrub that has established itself in Mediterranean climates worldwide. They found that the invasive species threatens native ecosystems not only through its prolific growth but also by fertilizing the surrounding soil with nitrogen – this effect markedly extended beyond the area occupied by the invader. This innovative method (called 15N isoscapes) is being published today (13 March) in the renowned journal 'Ecology Letters'.

Most plants can only take up nitrogen from the soil. The Sydney Golden Wattle (Acacia longifolia) in contrast, is able to assimilate nitrogen from the air with the help of nitrogenfixing bacteria. As a result, this acacia has a large advantage over native non nitrogen fixing species on nitrogen-poor soils such as the dunes on the Portuguese coast at Tróia which the research team from Bielefeld University are investigating. On some of these dunes, a massive encroachments of the non-native acacia has already taken place. It suppresses other plants by using more than its share of the limited nutrients and rainwater. Its leaves and branches also shade out smaller plants in the understory. The ecologists Professor Dr. Christiane Werner and her team - Katherine G. Rascher, Christine Hellmann, and Cristina Máguas - wanted to know whether the invasive impact of this acacia is even broader.

Through the decomposing leaves of these acacias, large amounts of fixed nitrogen originating from the air are passed into the soil. One central question for the researchers was whether the native plants in the neighbourhood of the invader use this nitrogen. The additional nutrients would then potentially enhance the growth rates of neighbouring native species. Although this seems positive at first glance, it has problematic consequences for the species diversity in the dune system, because 'dunes are sensitive ecosystems that depend on slow growth and a sustainable use of resources', Christiane Werner says. If the plants grow more quickly than usual, then they use more water, soils becomes drier, endangering the sensitive equilibrium between the native plant community.

For testing whether nitrogen from the air passes via the acacia to neighbouring plants that only use nitrogen from the soil, the researchers took advantage of a different isotopic forms of nitrogen: The most common stable isotope of nitrogen, 14N, has seven protons and seven neutrons, that is, 14 nuclear particles. The less abundant 'heavy' isotope of nitrogen has an additional neutron and thus a total of 15 nuclear particles, 15N. The concentration of 15N in the air is higher than that in the soil of the Portuguese dunes. Hence, if one species fixes nitrogen from the air and if neighbouring plants take up this additional nitrogen, then the leaves of these neighbouring plants should also reveal a higher concentration of heavy nitrogen isotopes.

The research team has now confirmed that the Portuguese crowberry (Corema album), a native shrub on the Portuguese coast, uses a significant amount of the nitrogen that the Sydney Golden Wattle fixes from the air. 'The effect of the non-native acacia on these shrubs is considerable', says Christiane Werner. Her team took leaf samples in a section of the dunes while mapping the locations of the plants. Using an isotope ratio mass spectrometer to analyse the proportion of 15N in the samples, they compared the results with the plant distribution maps. 'This showed that the acacias influence the nitrogen level and the growth of native plants for a radius of up to eight metres outside their canopy', says Christiane Werner. 'Although the acacia is present in only one-fifth of the area under study, it changes the nitrogen dynamics in almost two-thirds of this area'.

For the biologists, this is a significant finding, because it helps to understand how invasive species such as the Sydney Golden Wattle from Australia manage to proliferate in new ecosystems and suppress native species: in this case, fertilizing their surroundings contributes greatly to the success of this acacia.

The method the ecologists are applying is called 'isoscaping'. It is normally used to pinpoint the landscape in which material originates by determining the isotope ratios, e.g. of mineral or plant residues. The research team in Bielefeld is the first to downscale the procedure to the level of a plant community. Christiane Werner reports that the new method is not only suitable for measuring the impact of non-native plants. In future, it could also be used to study, for example, the effect of factory effluents or agricultural fertilizers on ecosystems.

Original publication:
Community scale 15N isoscapes: tracing the spatial impact of an exotic N2-fixing invader. Katherine G. Rascher, Christine Hellmann, Cristina Máguas, Christiane Werner. 13 March 2012, Ecology Letters, http://dx.doi.org/10.1111/j.1461-0248.2012.01761.x, Impact Factor 15.2
Contact:
Junior Professor Dr. Christiane Werner, Bielefeld University
Faculty of Biology/ Experimental and Systems Ecology
Telephone: +49 521 106-5574
Email: c.werner@uni-bielefeld.de

Jörg Heeren | idw
Further information:
http://www.uni-bielefeld.de/biologie/Oekosystembiologie/doc/oeko13.html
http://dx.doi.org/10.1111/j.1461-0248.2012.01761.x

More articles from Ecology, The Environment and Conservation:

nachricht Emissions from road construction could be halved using today’s technology
18.05.2020 | Schwedischer Forschungsrat - The Swedish Research Council

nachricht When every particle counts: IOW develops comprehensive guidelines for microplastic extraction from environmental samples
11.05.2020 | Leibniz-Institut für Ostseeforschung Warnemünde

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: Biotechnology: Triggered by light, a novel way to switch on an enzyme

In living cells, enzymes drive biochemical metabolic processes enabling reactions to take place efficiently. It is this very ability which allows them to be used as catalysts in biotechnology, for example to create chemical products such as pharmaceutics. Researchers now identified an enzyme that, when illuminated with blue light, becomes catalytically active and initiates a reaction that was previously unknown in enzymatics. The study was published in "Nature Communications".

Enzymes: they are the central drivers for biochemical metabolic processes in every living cell, enabling reactions to take place efficiently. It is this very...

Im Focus: New double-contrast technique picks up small tumors on MRI

Early detection of tumors is extremely important in treating cancer. A new technique developed by researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from normal tissue. The work is published May 25 in the journal Nature Nanotechnology.

researchers at the University of California, Davis offers a significant advance in using magnetic resonance imaging to pick out even very small tumors from...

Im Focus: I-call - When microimplants communicate with each other / Innovation driver digitization - "Smart Health“

Microelectronics as a key technology enables numerous innovations in the field of intelligent medical technology. The Fraunhofer Institute for Biomedical Engineering IBMT coordinates the BMBF cooperative project "I-call" realizing the first electronic system for ultrasound-based, safe and interference-resistant data transmission between implants in the human body.

When microelectronic systems are used for medical applications, they have to meet high requirements in terms of biocompatibility, reliability, energy...

Im Focus: When predictions of theoretical chemists become reality

Thomas Heine, Professor of Theoretical Chemistry at TU Dresden, together with his team, first predicted a topological 2D polymer in 2019. Only one year later, an international team led by Italian researchers was able to synthesize these materials and experimentally prove their topological properties. For the renowned journal Nature Materials, this was the occasion to invite Thomas Heine to a News and Views article, which was published this week. Under the title "Making 2D Topological Polymers a reality" Prof. Heine describes how his theory became a reality.

Ultrathin materials are extremely interesting as building blocks for next generation nano electronic devices, as it is much easier to make circuits and other...

Im Focus: Rolling into the deep

Scientists took a leukocyte as the blueprint and developed a microrobot that has the size, shape and moving capabilities of a white blood cell. Simulating a blood vessel in a laboratory setting, they succeeded in magnetically navigating the ball-shaped microroller through this dynamic and dense environment. The drug-delivery vehicle withstood the simulated blood flow, pushing the developments in targeted drug delivery a step further: inside the body, there is no better access route to all tissues and organs than the circulatory system. A robot that could actually travel through this finely woven web would revolutionize the minimally-invasive treatment of illnesses.

A team of scientists from the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart invented a tiny microrobot that resembles a white blood cell...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Dresden Nexus Conference 2020: Same Time, Virtual Format, Registration Opened

19.05.2020 | Event News

Aachen Machine Tool Colloquium AWK'21 will take place on June 10 and 11, 2021

07.04.2020 | Event News

International Coral Reef Symposium in Bremen Postponed by a Year

06.04.2020 | Event News

 
Latest News

Black nitrogen: Bayreuth researchers discover new high-pressure material and solve a puzzle of the periodic table

29.05.2020 | Materials Sciences

Argonne researchers create active material out of microscopic spinning particles

29.05.2020 | Materials Sciences

Smart windows that self-illuminate on rainy days

29.05.2020 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>