Around the globe, forests are found to be undergoing strong changes due to human influence already today.
Degradation of woods due to man-made climate change cannot be ruled out for the future, a Special Feature in the Journal of Ecology, led by a team of scientists of the Potsdam Institute for Climate Impact Research (PIK), now shows. To understand and improve the resilience of forests, a combination of approaches from small-scale field experiments to large-scale computer simulations can help, according to the studies. Taking a risk perspective, the scientists caution that global warming puts additional pressure on some of the most valuable ecosystems on Earth.
"Forests are probably more at risk than previously thought,” says Christopher Reyer of PIK, coordinator of the Special Feature and lead-author of an overview article. “The observed changes affect forests as important as the Amazon, but also forests on all continents, possibly pushing some of them towards tipping points.”
Up to now, no example could be found where forests tipped into a state where no regrowth is possible due to man-made climate change. Yet the overview article identifies substantial research gaps. “This is hardly good news,” Reyer says. “It is in fact scary how little we still know about the resilience of forests, despite all the scientific progress we present in this special issue. From a risk perspective, climate change puts additional pressure on an exceptionally valuable ecosystem whose stability up to now cannot be properly assessed.”
**Forests preserve biodiversity, provide timber, store CO2**
Besides being home to a large part of the world’s plants and animals, hence preserving biodiversity, forests are also of great economic relevance. They provide timber in many countries, as well as game and fruit. “Some tropical forests, such as the Amazon, are also key for regional water cycles,” says Milena Holmgren of the University of Wageningen in the Netherlands. "How dense these forests are, affects the amount of rainfall that is recycled and also the amount of water that is retained. When forests become less dense, a smaller amount of water is recycled as rain and also less water is retained in the soil. Less dense forests facilitate also the growth of grass which burns easily in dry seasons. Fire can change the rules of the game drastically because grass burns easily and recovers fast whereas trees are very sensitive and need more time. So once a forest has been opened and starts burning, the end result can be a system that resembles a savanna with much grass and fewer trees. This changes the habitat for plants, animals and people.”
“The fate of forests is important also because they store huge amounts of the greenhouse gas CO2,” adds Holmgren. “Loosing forests and releasing carbon to the atmosphere contributes to climate warming and to the impacts we start to see in many regions of the world.”
**"Alleviating the negative effects of climate change on reforestation efforts" **
To assess the resilience of forests, long time scales are important. Over 2000 years, tropical peat swamp forests from Malaysian Borneo showed to be resilient even under disturbances such as fire or climate variability related to the El Niño weather phenomenon. Recent burning and agricultural expansion however clearly changed the landscape by replacing tropical peat swamp forests with open or even no forest. Still, things are not straightforward. Drought, on the other hand, is found to have variable effects on different tree species in different regions, and seasons, one of the new studies shows. In the end, it is a complex combination of stress factors that is likely to impact forests’ resilience.
In Finland and Australia, scientists performed field experiments on regrowth of forests. A joint dutch-finish team examined how boreal peat bogs can shift to forests and concluded that shrubs can pave the way for greener tree dominated landscapes in the far northern hemisphere. The Australian team studied the timing of seeding and the use of seedlings in restoring sites. “Adapted restoration practices could help alleviate the negative effects of climate change on reforestation efforts,” says Rachel Standish of The University of Western Australia. “We have some encouraging findings here. This is even more important as the area of disturbed forest ecosystems is clearly growing.”
Article: Reyer, C., Brouwers, N., Rammig, A., Brook, B., Epila, J., Grant, R.F., Holmgren, M., Langerwisch, F., Leuzinger, S., Lucht, W., Medlyn, B., Pfeiffer, M., Steinkamp, J., Vanderwel, M., Verbeeck, H., Villela, D. (2014): Forest resilience and tipping points at different spatio-temporal scales: approaches and challenges. Journal of Ecology (online) [DOI:10.1111/1365-2745.12337]
Article: Reyer, C., Rammig, A., Brouwers, N., Langerwisch, F. (2014): Forest resilience, tipping points and global change processes. Journal of Ecology (online) [DOI:10.1111/1365-2745.12342]
Article: Camarero, J.J., Gazol, A., Sangüesa-Barreda, G., Oliva, J., Vicente-Serrano, S.M. (2014): To die or not to die: early warnings of tree dieback in response to a severe drought. Journal of Ecology (online)
Article: Cole, L.E.S., Bhagwat, S.A., Willis, K.J. (2014): Long-term disturbance dynamics and resilience of tropical peat swamp forests. Journal of Ecology (online) [DOI:10.1111/1365-2745.12329]
Article: Holmgren, M., Lin, C.-Y., Murillo, J.E., Nieuwenhuis, A., Penninkhof, J., Sanders, N., van Bart, T., van Veen, H., Vasander, H., Vollebregt, M.E., Limpens, J. (2014): Positive shrub-tree interactions facilitate woody encroachment in boreal peatlands. Journal of Ecology (online)
Article: Jakovac, A.C.C., Peña-Claros, M., Kuyper, T.W., Bongers, F. (2014): Loss of secondary-forest resilience by land-use intensification in the Amazon. Journal of Ecology (online)
Article: Standish, R.J., Daws, M.I., Gove, A.D., Didham, R.K., Grigg, A.H., Koch, J.M., Hobbs, R.J. (2014): Long-term data suggest jarrah-forest establishment at restored mine sites is resistant to climate variability. Journal of Ecology (online)
Article: Steinkamp, J., Hickler, T. (2014): Is drought-induced forest dieback globally increasing? Journal of Ecology (online)
Weblink to the articles once they're published: http://www.journalofecology.org/view/0/specialfeatures.html
For further information please contact:
PIK press office
Phone: +49 331 288 25 07
Jonas Viering | Potsdam-Institut für Klimafolgenforschung
NASA examines Peru's deadly rainfall
24.03.2017 | NASA/Goddard Space Flight Center
Steep rise of the Bernese Alps
24.03.2017 | Universität Bern
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
24.03.2017 | Materials Sciences
24.03.2017 | Physics and Astronomy
24.03.2017 | Physics and Astronomy