In the face of adverse conditions, people might feel tempted by two radically different options -- hunker down and wait for conditions to improve, or press on and hope for the best. It would seem that trees employ similar options when the climate turns dry and hot.
Two University of Washington researchers have uncovered details of the radically divergent strategies that two common tree species employ to cope with drought in southwestern Colorado. As they report in a new paper in the journal Global Change Biology, one tree species shuts down production and conserves water, while the other alters its physiology to continue growing and using water.
As the entire western United States becomes warmer and drier through man-made climate change, these findings shed light on how woody plants may confront twin scourges of less water and hot weather.
The authors, UW biology graduate student Leander Anderegg and biology professor Janneke Hille Ris Lambers, wanted to understand if different tree species employ similar coping strategies for drought, and how these strategies would affect their future ranges in a warmer and drier climate. They compared how two common tree species differ in terms of shape, growth rate and physiology across wet and dry portions of their native ranges.
"We really wanted to identify the entire suite of strategies that a plant can use to grow in drier environments, as well as which of these strategies each tree would employ," said Hille Ris Lambers.
Along the slopes of the La Plata Mountains in Colorado's San Juan National Forest, dry and hot conditions at lower elevations limit tree growth and survival. The ponderosa pine (Pinus ponderosa) grows along these lower elevations. Higher up the slopes, trembling aspens (Populus tremuloides) dominate, and the lowest point of the aspen's range overlaps with the higher reaches of the ponderosa pine.
In the summer of 2014, Anderegg and a team of UW undergraduates collected leaf, branch and tree ring samples of both trees at the extremes of these ranges to learn how they adapted to drought conditions, measuring qualities like growth rate and water tension within the woody tissue.
Anderegg discovered that the trembling aspen and ponderosa pine adopt opposite strategies to cope with drought, with implications for their range and survival.
"On average, this region has already warmed up over 1.5 degrees Fahrenheit in the last 30 years," said Anderegg. "And what were once 100-year droughts are expected to become more frequent in the coming centuries."
The ponderosa pine used a strategy of "drought avoidance" by conserving water, especially by shutting the tiny openings on its leaves to prevent water loss and slowing growth. The trembling aspen, in contrast, deployed strategies that would allow it to keep growing -- at least for a while -- during drought, with no change to water conservation strategies.
"On the dry end of their range, the trembling aspens are relatively short with these really fat leaves," said Anderegg. "Internally, they also grow really strong xylem vessels, which move water inside of the tree. As a consequence, they are much denser and they also grow slower."
These strategies may influence the contraction of each tree species' range over time. The trembling aspen's push to grow might make it more vulnerable to severe or prolonged drought, especially at its dry lower range. Anderegg believes the aspen's range might shrink in "fits and starts" as a hotter a drier climate settles in. A severe drought in 2002, he notes, already killed off large numbers of trembling aspen at the study site.
The ponderosa pine's strategy of "drought avoidance" might mean that its range will contract more gradually than the trembling aspen's, the authors note. These differences in adaptation will reshape forest ecosystems in the face of climate change, they believe. Anderegg and Hille Ris Lambers would like to identify the tree life stages most vulnerable to drought, which might affect how quickly their ranges contract, and what forest policymakers could do to try to cope with these changes.
"If we know how the forests will change, we can hopefully manage things so that we don't lose the things we love and rely on -- things like air and water purification, erosion control and forest biodiversity," said Anderegg. "We'd like to be able to mitigate some of the negative effects to this vast public resource and keep climate change from being hugely detrimental."
Their research was funded by the UW Biology Edwards Grant, the Charles Redd Center for Western Studies, Sigma Xi, the American Alpine Club and the National Science Foundation.
Grant numbers: DGE-1256082 (NSF).
James Urton | EurekAlert!
Transport of molecular motors into cilia
28.03.2017 | Aarhus University
Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
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...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
28.03.2017 | Life Sciences
28.03.2017 | Information Technology
28.03.2017 | Physics and Astronomy