This is a question of increasing relevance in the field of climate change and is the focus of a new study to be published in the journal Proceedings of the Royal Society of London on 20 February. The study suggests that the answer to this question may have as much to do with the biological interactions that shape communities as with the effects of climate change itself.
The study's insights are based on a novel approach by Eric Post, a Penn State University professor of biology, who simulated climate change and integrated the effects of large, plant-eating mammals in a 10-year arctic field experiment. The results of the research suggest that plant communities in the Arctic are more likely to resist destabilization by climate change if populations of caribou, musk ox, and other large herbivores remain intact. "The study demonstrates that grazing by these large herbivores maintains plant species diversity, while warming reduces it," Post said. "Plant communities with lower diversity display a greater tendency toward instability under warming, a pre-cursor to the loss of such communities."
Post explained that climate-change research in the 1980s and 1990s was focused primarily on how fluctuations in such factors as temperature, precipitation, and nutrient availability directly affected plant communities. "That research was important and enlightening, but what it did not emphasize were the indirect effects of climate change -- how interactions among species may shape the responses of those species to warmer temperatures," Post said. "If the planet continues to warm by 1.5-to-3.0 degrees Celsius over the next century, as the models predict, we need to know not only what the warming will do to plants and animals directly, but also how species' interactions may influence those effects of warming."
Post began the study in a remote, low-Arctic plant community near Kangerlussuaq, Greenland in 2002. To simulate the effects of the 1.5-to-3.0-degrees-Celsius warming that is predicted to occur over the next century, he erected special warming chambers -- cone-shaped hollow structures that create a greenhouse effect. Some areas on which these warming chambers were placed were left open to grazing by caribou and musk ox -- two ecologically important large herbivores in the Arctic -- while separate 800-square-meter areas that also received warming chambers were fenced off to exclude the animals. In this way, Post created two very different environments: one in which plants and herbivores continued to live together as the temperatures climbed within the warming chambers; the other in which the animals were not present and the plants were left ungrazed.
"The study tested a classic ecological hypothesis, but with a new angle," Post said. "Ecologists have argued for decades over whether species-rich plant communities are more stable, and, hence, persistent in the face of environmental disturbance, than species-poor communities. This study added a layer of complexity by asking whether large herbivores contribute to the diversity-stability relationship in a climate-change context."
After 10 years of careful observation of the Kangerlussuaq, Greenland plant communities, Post found that the grazed and ungrazed sections of land did indeed fare quite differently in their responses to warmer temperatures. "This study confirmed that caribou and musk ox act as a buffer against the degradative effects of warming on plant species diversity," Post said. He found that shrubs such as willow and birch became the dominant plants in response to warming where the herbivorous animals were excluded from the ecosystem. "When these shrubs expand in the plant community, they tend to shade their neighbors, and the build-up of leaf litter around the shrubs tends to cool the soil surface, reducing the availability of soil nutrients for other plants," Post said. "As a result, shrubs can quickly out-compete other plants and reduce species diversity in the process. On the other hand, in those areas where caribou and musk ox were able to graze freely, shrub responses to warming were muted, and species diversity within the plant community was maintained."
Post said the take-home message from his study is that, in a warming climate, intact populations of large herbivores may be crucial to the maintenance of plant-community diversity and to the persistence of existing plant communities. "What this experiment suggests is that factors that threaten the persistence of large herbivores may threaten the plant communities they exist in, as well. Conservation of these herbivores in the rapidly changing Arctic will require careful mediation of interacting stressors such as human exploitation, mineral extraction, and the direct effects of climate change," Post said.
Post said that the next step in his research will be to study the contribution of plant diversity to long-term stability of carbon dynamics in the atmosphere and in the soil.
The research was funded by the National Geographic Society's Committee for Research and Exploration, with additional funding from the Office of Polar Programs at the U.S. National Science Foundation.
[ Katrina Voss ]
Barbara Kennedy (PIO) firstname.lastname@example.org, 814-863-4682
Eric Post email@example.com
High-resolution images associated with this research are online at http://www.science.psu.edu/news-and-events/2013-news/Post2-2013.
(for all images): Eric Post, Penn State University
IMAGE CAPTIONS (top to bottom on the webpage listed above)
Image 1: An adult male caribou in Greenland.
Image 2: Two adult male muskoxen in Greenland.
Image 3: Inland ice shelves in Greenland.
Image 4: To study how ecological communities react to rising temperatures, Eric Post erected special warming chambers to simulate a greenhouse effect in a remote, low-Arctic plant community near Kangerlussuaq, Greenland.
Image 5: An adult male muskox in Greenland.
Image 6: Adult male caribou in Greenland.
Image 7: Two adult male muskoxen in Greenland.
Image 8: A cotton-grass plant grows in Greenland.
Image 9: Inland ice shelves in Greenland.
National Geographic Society (7442-03)
National Science Founcation (DEB-0124031)
Barbara Kennedy | Source: EurekAlert!
Further information: www.psu.edu
Further Reports about: ant species > Arctic Ocean > Climate change > greenhouse effect > Greenland > ice shelves > Kangerlussuaq > plant communities > plant species > species diversity > warmer temperatures
More articles from Ecology, The Environment and Conservation:
Atlantic Research Expedition Uncovers Vast Methane-Based Ecosystem
24.05.2013 | University of North Carolina Wilmington
Reforestation study shows trade-offs between water, carbon and timber
24.05.2013 | Arizona State University
This morning at 05:45 CEST, the earth trembled beneath the Okhotsk Sea in the Pacific Northwest. The quake, with a magnitude of 8.2, took place at an exceptional depth of 605 kilometers.
Because of the great depth of the earthquake a tsunami is not expected and there should also be no major damage due to shaking.
Professor Frederik Tilmann of the GFZ German Research Centre for Geosciences: "The epicenter is exceptionally deep, far below the earth's crust in the mantle. Such strong ...
The Ring Nebula's distinctive shape makes it a popular illustration for astronomy books. But new observations by NASA's Hubble Space Telescope of the glowing gas shroud around an old, dying, sun-like star reveal a new twist.
"The nebula is not like a bagel, but rather, it's like a jelly doughnut, because it's filled with material in the middle," said C. Robert O'Dell of Vanderbilt University in Nashville, Tenn.
He leads a research team that used Hubble and several ground-based telescopes to obtain the best view yet of ...
New indicator molecules visualise the activation of auto-aggressive T cells in the body as never before
Biological processes are generally based on events at the molecular and cellular level. To understand what happens in the course of infections, diseases or normal bodily functions, scientists would need to examine individual cells and their activity directly in the tissue.
The development of new microscopes and fluorescent dyes in ...
A fried breakfast food popular in Spain provided the inspiration for the development of doughnut-shaped droplets that may provide scientists with a new approach for studying fundamental issues in physics, mathematics and materials.
The doughnut-shaped droplets, a shape known as toroidal, are formed from two dissimilar liquids using a simple rotating stage and an injection needle. About a millimeter in overall size, the droplets are produced individually, their shapes maintained by a surrounding springy material made of polymers.
Droplets in this toroidal shape made ...
Frauhofer FEP will present a novel roll-to-roll manufacturing process for high-barriers and functional films for flexible displays at the SID DisplayWeek 2013 in Vancouver – the International showcase for the Display Industry.
Displays that are flexible and paper thin at the same time?! What might still seem like science fiction will be a major topic at the SID Display Week 2013 that currently takes place in Vancouver in Canada.
High manufacturing cost and a short lifetime are still a major obstacle on ...
24.05.2013 | Life Sciences
24.05.2013 | Ecology, The Environment and Conservation
24.05.2013 | Physics and Astronomy
17.05.2013 | Event News
15.05.2013 | Event News
08.05.2013 | Event News