Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Ecosystem Management Must Consider Human Impact Too

For a long time, ecologists have believed—and others accepted—that when it comes to whether a land mass is covered with forests or grasslands, climate controls the show. They thought that the amount of rain, temperature and frequency of wildfires determine whether the ground will be covered with trees or grasses.

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
Further information:

More articles from Ecology, The Environment and Conservation:

nachricht Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>