The forest we are used to looking at is not at all in equilibrium. Since the Ice Age, a number of plants have been 'missing' in Northern Europe, i.e. species that have not yet arrived.
Heartleaf Oxeye is an example of a species that has not yet returned to Northern Europe since the last Ice Age, but which we have helped along by planting in our gardens. Here it was found in the Danish countryside.
Credit: Photo: Jens-Christian Svenning, Aarhus University
The same applies in many other parts of the world. Similarly, there is evidence that -- even today -- it often takes a very long time before plants follow when glaciers retreat, or the climate changes. In future, such disequilibrium will become the norm in the plant communities on Earth. This has been demonstrated by a new synthesis carried out by two researchers at Aarhus University -- Professor of Biology Jens-Christian Svenning and Assistant Professor Brody Sandel.
Professor Svenning explains: "In the climate debate, even researchers have had a tendency to overlook the fact that ecological dynamics can be slow. However, our forests take an extremely long time to adapt. For example, we still have a small amount of small-leaved lime in Denmark, which has held on since the warm period during the Bronze Age, i.e. about 3000 years. Perhaps it will now get another chance to spread when the summers once more get warmer. However, such expansion would take a long time, as lime is not a particularly fast-growing tree or particularly good at dispersing, even under optimum conditions. The climate will change considerably in the course of a single tree generation so we should not assume that the forest we're looking at in a given place is suitable for the climate. Future climate will constantly shift, which will increasingly result in these strange situations of disequilibrium."
Even fast spreaders such as some invasive exotic plants remain in disequilibrium for decades or centuries. Shown here is a Norway maple, a highly invasive tree species in North America that may nevertheless still take many decades to spread across even small landscapes.
Photo: Lennarth Skov Espersen, http://www.fotoinaturen.dk.The challenges we face
This would be challenging for everyone -- for the managers, for the people who use the countryside in one way or another, and also for the researchers who are used to working with ecosystems that are much more balanced. Plant life and ecosystems will become much more dynamic and often out of sync with the climate.
We're causing so many changes to the climate, but at the same time nature is SO slow. Just think of a tree generation. Our entire culture is based on something that was, if not in complete equilibrium, then at least relatively predictable. We're used to a situation where flora, fauna and climate are reasonably well matched. In future, this equilibrium will shift on an ongoing basis, and there will be plenty of mismatches. That's what we'll have to work with."
Professor Svenning also calls for caution: "With nature in such a state of disequilibrium, human introduction of new species will play a key role. Take cherry laurel, for example, which we see in many gardens in Denmark. It's ready to spread throughout the Danish countryside. If it were to migrate unaided from its nearest native site in South-East Europe to Denmark, it would take thousands of years. Horticulturists now help it along. This will help the species survive, but can also cause northern species in Denmark to become extinct more rapidly. The cherry laurel is an evergreen, and if it disperses on the forest floor, it may create too much shade for the existing flora on the forest floor to survive. At the same time, the disequilibrium presents the advantage that such dispersal will take decades despite the contribution of horticulturists," Professor Svenning concludes.
Cherry laurel is another example of a species that has not yet returned to Northern Europe since the last Ice Age, but which we have helped along by planting in our gardens. Here it was found in the English countryside. Photo: Jens-Christian Svenning, Aarhus University.For more information, please contact
Jens-Christian Svenning | EurekAlert!
GPM sees deadly tornadic storms moving through US Southeast
01.12.2016 | NASA/Goddard Space Flight Center
Cyclic change within magma reservoirs significantly affects the explosivity of volcanic eruptions
30.11.2016 | Johannes Gutenberg-Universität Mainz
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy