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
"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."
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."
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
Barbara Wankerl | EurekAlert!
Listening in: Acoustic monitoring devices detect illegal hunting and logging
14.12.2017 | Gesellschaft für Ökologie e.V.
How fires are changing the tundra’s face
12.12.2017 | Gesellschaft für Ökologie e.V.
DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.
Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
15.12.2017 | Trade Fair News
15.12.2017 | Physics and Astronomy
15.12.2017 | Information Technology