Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Plants' defensive responses have downstream effects on nearby ecosystems


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 and our newsroom at

Twitter @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 First time-lapse footage of cell activity during limb regeneration
25.10.2016 | eLife

nachricht Phenotype at the push of a button
25.10.2016 | Institut für Pflanzenbiochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Enormous dome in central Andes driven by huge magma body beneath it

25.10.2016 | Earth Sciences

First time-lapse footage of cell activity during limb regeneration

25.10.2016 | Life Sciences

Deep down fracking wells, microbial communities thrive

25.10.2016 | Earth Sciences

More VideoLinks >>>