Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Munching Bugs Thwart Eager Trees, Reducing the Carbon Sink

02.03.2015

In a high carbon dioxide world, the trees would come out ahead. Except for the munching bugs.

A new study published today [Monday, March 2, 2015] in Nature Plants shows that hungry, plant-eating insects may limit the ability of forests to take up elevated levels of carbon dioxide in the atmosphere, reducing their capacity to slow human-driven climate change.


Photo courtesy of John Couture, UW-Madison

A forest tent caterpillar rests on an aspen leaf. These caterpillars are found in hardwood forests throughout the United States, where they feed on the leaves of trees like aspen and birch.


Photo courtesy of John Couture, UW-Madison

An aerial view of the Aspen Free-Air Carbon dioxide and ozone Enrichment (Aspen FACE) experiment site once located near Rhinelander, Wisconsin. The circular plots consist of aspen and birch trees, surrounded by PVC pipes that allowed scientists to vent carbon dioxide and ozone gas into the air around the trees, to study what effect high levels of these gases have on the activity of insects that feed on them.

The finding is significant because climate change models typically fail to consider changes in the activities of insects in the ecosystem, says Richard Lindroth, a professor of ecology at the University of Wisconsin-Madison and the leader of the study. The research suggests it’s time to add insects to the models.

Carbon dioxide typically makes plants grow faster and makes them more efficient in how they use nutrients. But the amount of damage caused by leaf-munching bugs in the study nearly doubled under high carbon dioxide conditions, leading to an estimated 70g of carbon-sequestering biomass lost per meter squared per year.

“This is the first time, at this scale, that insects have been shown to compromise the ability of forests to take up carbon dioxide,” Lindroth says.

In addition, as feeding increased, more nutrients moved from the canopy to the forest floor in the form of insect fecal material and chewed-on leaf scraps, mixing into the soil and likely altering the nutrient profile of the forest.

“Insects are munching on leaves and they’re pooping out remnants, so they are changing the timing of nutrient cycling as well as the quality,” Lindroth says.

John Couture, a former graduate student in Lindroth’s lab and the lead author of the study, spent three years with his team studying the impact of elevated carbon dioxide alone, elevated ozone (which is highly toxic to plants) alone, and elevated levels of both gases combined on stands of aspen and birch growing in what was once one of the largest simulated ecosystems in the world, the Aspen Free-Air Carbon dioxide and ozone Enrichment (Aspen FACE) experiment located near Rhinelander, Wisconsin.

Unlike a greenhouse or atmospheric chamber, the FACE site (now decommissioned) was a massive outdoor experimental area that allowed trees to grow under natural conditions, like natural soil, sunlight, and rainfall. The only artificial conditions were those that were experimentally manipulated.

The site consisted of a dozen stands of trees growing in 30 meter diameter plots, surrounded by a network of PVC pipes designed to vent gases into the environment around them.

They were exposed to carbon dioxide and ozone at levels predicted for the year 2050, although Lindroth says the 560 parts-per-million carbon dioxide level studied is probably too low.

The trees were planted as saplings in the mid-1990s and by the time Couture collected data for the study from 2006 though 2008, they had grown to resemble any number of the disturbed forest stands found throughout Wisconsin.

Couture and his team walked through each site, clipping leaves from the canopy using scissors at the end of pruner poles or from scaffolding near the top of the canopy. They also set out frass baskets — laundry baskets lined with sheets — to collect scraps of leaves dropped by messy, munching caterpillars and other bugs dining in the canopy, and to collect their fecal droppings.

Tens of thousands of leaves and countless frass baskets later, Couture measured the amount of leaf area consumed by the insects in each plot and sifted through the frass and food droppings in the baskets to assess just how much eating the bugs were doing, to measure the amount of nutrients leaving the trees via their droppings, and to assess the loss of tree biomass.

Why insects would do more munching in a carbon dioxide rich forest is in part a matter of chemistry. Because carbon dioxide is a limiting resource for plant growth, high levels of the gas change the way trees use other resources, like nitrogen, typically leading to less nutritious plants.

“It’s like a slice of Wonder Bread versus a slice of high density, protein-rich bakery bread; there’s a lot more protein in the bakery bread than the white bread,” says Couture. “Insects have a base level of nutrients they need in order to grow and to reach that, they can choose either to eat higher-nutrient food — unfortunately, insects don’t always have that choice — or to eat more.”

Overall, the team found high ozone plots were less hospitable to insects, reducing their munching behavior and leading to less biomass loss.

With the findings, the researchers created models allowing them to predict what could happen in forests under changing environmental conditions.

“The big question is, will northern forests grow faster under elevated carbon dioxide?” says Lindroth. “Carbon dioxide is a substrate for photosynthesis. It gets converted into sugars, which then become plant biomass. Will trees take up more carbon dioxide and thus help reduce its increase in the atmosphere?”

As humans continue to contribute more carbon dioxide to Earth’s atmosphere, the answer should be yes as trees act as sponges for the greenhouse gas. But it turns out, very hungry caterpillars and their bug brethren — in their own quest for food in an elevated carbon dioxide environment — may limit that growth and reduce the capacity of forests to slow climate warming.

—Kelly April Tyrrell, kelly.tyrrell@wisc.edu, 608-262-9772

Contact Information
John Couture, 269-760-4922 (unavailable 2/28 through 3/6), jjcouture@wisc.edu and Rick Lindroth, 608-886-2999 (from 2/26 through 3/6) or 608-262-6792 anytime thereafter, richard.lindroth@wisc.edu

John Couture | newswise
Further information:
http://www.wisc.edu

Further reports about: Atmosphere Bugs Trees biomass canopy carbon dioxide caterpillars conditions dioxide forests insects leaves models nutrients ozone

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>