Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Warm winters let trees sleep longer

30.10.2013
Climate change alters timing of spring growth in forests

In the temperate zones, vegetation follows the change of the seasons. After a winter pause, plants put out new growth in spring. Research has now brought a new correlation to light: The colder the winter, the earlier native plants begin to grow again.


For their experiments, TUM researchers used twigs around 30 centimeters long from 36 different trees and shrubs, which they exposed to different temperature and light conditions in climate chambers. Each climate chamber experiment lasted six weeks. The twigs came from the "Weltwald" or "World Forest" near Freising, Germany, in which Bavarian state foresters have planted stands of trees from different climate regions.

Credit: Photo by Julia Laube Copyright TU Muenchen

Since warmer winters can be expected as the climate changes, the spring development phase for typical forest trees might start later and later – giving an advantage to shrubs and invasive trees that don't depend on the cold.

In a recently published study, researchers at the Technische Universitaet Muenchen (TUM) investigated 36 tree and shrub species. Their work delivered a surprising result, as lead author Julia Laube explains: "Contrary to previous assumptions, the increasing length of the day in spring plays no big role in the timing of budding. An ample 'cold sleep' is what plants need in order to wake up on time in the spring."

This applies above all to native tree species such as beech and oak, because they rely on resting in the cold to protect themselves from freezing by late spring frosts. A different behavior is observed among pioneer species – including shrubs such as hazel bushes and primary settlers such as birch trees – and among species like locust and walnut that have moved in from warmer climate zones. "These trees take the risk of starting earlier in the spring, because they are less strongly dependent on the cold periods," Laube says, "and in addition they sprout more quickly as temperatures rise."

Advantage for shrubs and new tree species

There may be consequences for the forest ecosystem. After mild winters, the native species run a higher risk of developing their leaves too late. In that case, more daylight reaches the forest floor, and that benefits lower-growing shrubs and invasive tree species. They sprout earlier, to the detriment of native species: Young trees for example, still low to the ground, may not receive the light they need to grow.

"Even under warmer conditions, we won't be seeing 'green Christmases' under freshly blooming trees," says Prof. Annette Menzel, TUM Chair for Ecoclimatology and a fellow of the TUM Institute for Advanced Study. "Nonetheless, the differing growth patterns will affect the entire plant and animal world. The native tree species in our forests have only a limited ability to adapt themselves to climate change."

Shortened winter in the climate chamber

For their experiments, the researchers used twigs around 30 centimeters long from 36 different trees and shrubs, which they exposed to different temperature and light conditions in climate chambers. Each climate chamber experiment lasted six weeks. The twigs came from the "Weltwald" or "World Forest" near Freising, in which Bavarian state foresters have planted stands of trees from different climate regions.

The cold effect showed most strongly with the beeches, the hornbeams, and the North American sugar maple. With shortened cold periods, bud burst occurred significantly later. In contrast, the lilac, the hazel bush, and the birch proved to be less dependent on the cold.

"Overall, however, a chaotic picture emerges," Menzel adds. "Through warmer winters, the usual sequence of leaf development can get completely mixed up. Many of the cultivated species that are at home today in central Europe come originally from warmer climate zones. In the absence of adequate protection against freezing, they could become victims of their own too-flexible adaptation – and freeze to death in a late frost in the spring."

Publication:

Chilling outweighs photoperiod in preventing precocious spring development; Julia Laube, Tim H. Sparks, Nicole Estrella, Josef Höfler, Donna P. Ankerst and Annette Menzel; Global Change Biology (Oct. 30, 2013), doi: 10.1111/gcb.12360

Contact:

Prof. Dr. Annette Menzel
Technische Universitaet Muenchen
Chair of Ecoclimatology
T: +49.8161.71.4740
E: amenzel@wzw.tum.de
W: http://www.oekoklimatologie.wzw.tum.de
Technische Universitaet Muenchen (TUM) is one of Europe's leading research universities, with around 500 professors, 10,000 academic and non-academic staff, and 35,000 students. Its focus areas are the engineering sciences, natural sciences, life sciences and medicine, reinforced by schools of management and education. TUM acts as an entrepreneurial university that promotes talents and creates value for society. In that it profits from having strong partners in science and industry. It is represented worldwide with a campus in Singapore as well as offices in Beijing, Brussels, Cairo, Mumbai, and São Paulo. Nobel Prize winners and inventors such as Rudolf Diesel and Carl von Linde have done research at TUM. In 2006 and 2012 it won recognition as a German "Excellence University." In international rankings, TUM regularly places among the best universities in Germany.

Barbara Wankerl | EurekAlert!
Further information:
http://www.tum.de

More articles from Ecology, The Environment and Conservation:

nachricht Value from wastewater
16.08.2017 | Hochschule Landshut

nachricht Species Richness – a false friend? Scientists want to improve biodiversity assessments
01.08.2017 | Carl von Ossietzky-Universität Oldenburg

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>