Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Plants' defensive responses have downstream effects on nearby ecosystems

18.03.2015

Chemical changes that occur in tree leaves after being attacked by insects and mammals can impact nearby streams, which rely on fallen plant material as a food source, report scientists from the University of Chicago Department of Ecology and Evolution. The study, published March 17 in the journal Proceedings of the Royal Society B, shows how interactions between terrestrial and aquatic ecosystems are an essential part of understanding ecological responses to climate change.

Graduate student Sara Jackrel and Timothy Wootton, PhD, professor in the Department of Ecology and Evolution, simulated herbivory, or the activity of insects eating leaves, on red alder trees in a forest on the Olympic Peninsula in Washington state.


This is a typical river reach on the Merrill & Ring Tree Farm, Olympic Peninsula, Washington.

Credit: Sara Jackrel

Their research showed caterpillars ate fewer leaves from the stressed trees than those that were left alone. Leaves from these stressed trees also decomposed much more slowly when submerged in nearby streams, and further results suggest that the trees funneled a valuable nutritional resource away from the leaves as a defensive response to animal attacks.

"Terrestrial herbivory could have innumerable effects on leaf chemistry, and our simulation had a very strong effect in streams," said Jackrel, the study's lead author. "The tree's response to herbivory had a cascading effect across an ecosystem boundary, into another trophic level entirely. The important finding was making that indirect link from a terrestrial system into an aquatic system."

Plants generate many defensive responses to being attacked by insects and other animals. Some produce tannins and compounds that are toxic or taste bad to discourage herbivores from eating them. Others may even release chemicals that attract predators for the particular insect attacking the plant.

Insects and microbe decomposers that live in streams depend on a variety of nutritionally diverse leaf litter as a food sources. They play no direct role in the interactions between trees and their herbivores, but the new study shows how the composition of those leaves is shaped by their activity,

During her fieldwork, Jackrel mimicked the activity of caterpillars by systematically punching holes in the alder leaves with an office hole punch. She also painted the leaves with methyl jasmonate, a chemical that trees release under stress, to enhance the defensive response to the hole punches. Some trees were fertilized with phosphorus, while others were not.

Jackrel then buried packages of leaves and placed others underwater in a stream to test how quickly they decomposed in both soil and water. Caterpillars were also allowed to feed on treated and untreated leaves to test their preferences.

Leaves from trees that received both fertilizer and the herbivory treatment decomposed the most slowly. Caterpillars and aquatic insects ate fewer of these leaves than those from untreated trees as well.

Nitrogen levels were also much lower in the treated leaves. Insects value nitrogen as a nutrient, and the study results suggest that trees alter nitrogen levels to deter them from eating more leaves, perhaps by storing it the trunk or roots.

Understanding how trees' defensive responses to natural herbivores impact nearby streams will help scientists better predict the effects of climate change and other human activity like logging and agriculture.

"With climate change, insect communities are going to change," Jackrel said. "So understanding fundamentally how these communities naturally affect leaf chemistry, and how that might affect stream systems, is a critical reference to have. Then we can work to predict how climate change, along with other anthropogenic changes, might be affecting aquatic systems."

###

The study, "Cascading effects of induced terrestrial plant defences on aquatic and terrestrial ecosystem function," was supported by the National Science Foundation, the U.S. Department of Education, the University of Chicago Hinds Fund and an Olympic National Resources grant.

About the University of Chicago Medicine

The University of Chicago Medicine & Biological Sciences is one of the nation's leading academic medical institutions. It comprises the Pritzker School of Medicine, a top 10 medical school in the nation; the University of Chicago Biomedical Sciences Division; and the University of Chicago Medical Center, which recently opened the Center for Care and Discovery, a $700 million specialty medical facility. Twelve Nobel Prize winners in physiology or medicine have been affiliated with the University of Chicago Medicine.

Visit our research blog at sciencelife.uchospitals.edu and our newsroom at uchospitals.edu/news.

Twitter @UChicagoMed

Facebook.com/UChicagoMed

Matt Wood | EurekAlert!

Further reports about: Ecosystem Plants activity aquatic downstream effects ecosystems herbivores herbivory insects leaves terrestrial

More articles from Life Sciences:

nachricht New photocatalyst speeds up the conversion of carbon dioxide into chemical resources
29.05.2017 | DGIST (Daegu Gyeongbuk Institute of Science and Technology)

nachricht Copper hydroxide nanoparticles provide protection against toxic oxygen radicals in cigarette smoke
29.05.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Strathclyde-led research develops world's highest gain high-power laser amplifier

The world's highest gain high power laser amplifier - by many orders of magnitude - has been developed in research led at the University of Strathclyde.

The researchers demonstrated the feasibility of using plasma to amplify short laser pulses of picojoule-level energy up to 100 millijoules, which is a 'gain'...

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

New insights into the ancestors of all complex life

29.05.2017 | Earth Sciences

New photocatalyst speeds up the conversion of carbon dioxide into chemical resources

29.05.2017 | Life Sciences

NASA's SDO sees partial eclipse in space

29.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>