Maybe not, say two scientists writing in the Oct. 14, 2011, issue of the journal Science. In a review of their papers in a Perspectives article in the same issue of Science, Michigan Technological University researcher Audrey Mayer suggests that future studies need to consider other factors—specifically, grazing patterns and human activities—when planning for sustainable management of the world’s forests and savannas or prairies.
“Humans like to think everything is linear,” says Mayer, an assistant professor of ecology and environmental policy with joint appointments in Michigan Tech’s School of Forest Resources and Environmental Science and the College of Sciences and Arts Department of Social Science. “So we have assumed that if we want to restore a forest where there is now savanna, that we just need to plant some trees and the spaces between them will fill in with trees. Not so.”
The grasses of savannas and prairies are highly flammable and promote their own spread through frequent fires, she explains. “Simply planting some saplings will mean that those saplings will die in the first fire that sweeps through. Far more effort and understanding is required to restore these ecosystems.”
Mayer’s graduate student, Azad Henareh Khalyani, is a co-author on the Perspectives article. He is studying similar dynamics in oak forests and savannas in Iran.
The papers they discuss are written by A. Carla Staver of Princeton University and colleagues, and Marina Hirota and colleagues of Wageningen University, The Netherlands.
They found that forests, savannas and grasslands worldwide are maintained by the same three mechanisms: a strong feedback between vegetation and precipitation; a strong feedback between rainfall seasonality and grass; and a very strong feedback between grass and fire.
Both reports identify an unstable state at 50 to 60 percent tree cover; either trees take hold and promote their own growth hydrologically (and suppress fire), or grasses take hold and promote their expansion through fire, Mayer says. “This work has implications for the resilience of these ecosystems in the Southern Hemisphere,” she notes.
“Large areas of savanna in Africa could shift to forest if fire and grazing are suppressed, and large areas of forest in South America could convert to savanna as climate change and local human impacts such as logging interact with rainfall seasonality and fire.”
However, Staver and Hirota do not analyze several other important mechanisms, Mayer goes on to say. Large herbivores such as horses and antelope evolved in concert with savannas and grasslands, and their grazing in turn has an impact on the perpetuation of their feeding areas, she explains. “Topography—the surface features of a place—may also influence microclimates and thus, fire spread and vegetation. Finally, prehistoric and historic human activities had a sizable influence on the forests, savannas and grasslands that exist today.”
Human activity will continue to influence the distribution and resilience of forests and savannas in a number of ways, Mayer and Henareh observe. “Fire suppression, grazing of domesticated animals, forest harvests, restoration efforts and contributions to climate change all have effects,” they point out. “Future studies should examine the impacts of human activities on the natural feedback systems in forests and savannas in both hemispheres, to assist the development of better-informed management and restoration plans.”
Jennifer Donovan | Newswise Science News
Waste in the water – New purification techniques for healthier aquatic ecosystems
24.07.2018 | Eberhard Karls Universität Tübingen
Plenty of habitat for bears in Europe
24.07.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig
New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...
Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...
Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.
When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
17.08.2018 | Event News
08.08.2018 | Event News
27.07.2018 | Event News
17.08.2018 | Physics and Astronomy
17.08.2018 | Information Technology
17.08.2018 | Life Sciences