Researchers discover rapid change in ecosystem services
Half of the Earth's land mass is made up of rangelands, which include grasslands and savannas, yet they are being transformed at an alarming rate. Woody plants, such as trees and shrubs, are moving in and taking over, leading to a loss of critical habitat and causing a drastic change in the ability of ecosystems to produce food — specifically meat.
Grasslands are being transformed at an alarming rate as woody plants, such as trees and shrubs, take over. This is leading to a loss of critical habitat and causing a drastic change in the ability of ecosystems to produce food. This is one example near the Santa Rita mountains in Arizona.
Credit: Osvaldo Sala
Researchers with Arizona State University's School of Life Sciences led an investigation that quantified this loss in both the United States and Argentina. The study's results are published in today's online issue of the scientific journal Proceedings of the National Academy of Sciences (PNAS).
"While the phenomenon of woody plant invasion has been occurring for decades, for the first time, we have quantified the losses in ecosystem services," said Osvaldo Sala, Julie A. Wrigley Chair and Foundation Professor with ASU's School of Life Sciences and School of Sustainability. "We found that an increase in tree and shrub cover of one percent leads to a two percent loss in livestock production." And, woody-plant cover in North America increases at a rate between 0.5 and two percent per year.
In recent years, the U.S. government shelled out millions of dollars in an effort to stop the advance of trees and shrubs. The U.S. Natural Resources Conservation Service spent $127 million from 2005-2009 on herbicides and brush management, without a clear understanding of its economic benefit.
The research team used census data from the U.S. and Argentina to find out how much livestock exists within the majority of the countries' rangelands. In both countries, the team studied swaths of rangeland roughly the size of Texas — approximately 160 million acres each. These lands support roughly 40 million heads of cattle. Researchers also used remote sensors to calculate the production of grasses and shrubs. And, to account for the effects of different socioeconomic factors, researchers quantified the impact of tree cover on livestock production in two areas of the world that have similar environments, but different level of economic development.
Surprisingly, the presence of trees explained a larger fraction of livestock production in Argentina than in the US.
"What's happening in Argentina seems to be a much narrower utilization of rangelands," added Sala. "The land there is mostly privately-owned and people who have ranches are producing predominantly meat to make a profit. But in the U.S., many people who own ranches don't actually raise cattle. They are using the land for many other different purposes."
While ranchers clearly depend on grasslands to support healthy livestock, ecosystems also provide a range of other services to humans. Stakeholders such as conservationists, farmers, builders, government entities and private landowners, depend on the land for a variety of reasons and each has different values and land use needs.
Why are trees and shrubs taking over grasslands? There are several hypotheses as to why woody plant encroachment is happening. Fire reduction, grazing intensity, climate change, and increased carbon dioxide in the atmosphere are some widely held beliefs as to the cause. However, Sala's study is focused not on the cause, but rather on the cost of this change to people.
"For each piece of land, there are different people who have an interest in that land and they all have different values. And, they are all okay," said Sala. "However, in order to negotiate how to use the land and to meet the needs of these different stakeholders, we need concrete information. We now know how much increase in tree cover is affecting the cattle ranchers."
Sala and his colleagues hope that the information found in their study will be used to inform discussions as policy makers and other stakeholders negotiate changes in land use. Researchers who took part in the study include Sala and Billie Turner II with ASU, José Anadón with City University of New York, and Elena Bennett with McGill University. National Academies Keck Futures Initiative and the U.S. National Science Foundation funded the study.
ASU's School of Life Sciences is an academic unit of the College of Liberal Arts and Sciences.
Sandra Leander | Eurek Alert!
Greenhouse gases unbalanced
25.03.2015 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
Nova Southeastern University researcher part of team researching DNA of tigers
23.03.2015 | Nova Southeastern University
In an experiment at the Department of Energy's SLAC National Accelerator Laboratory, scientists precisely measured the temperature and structure of aluminum as...
The IPH presents a solution at HANNOVER MESSE 2015 to make ship traffic more reliable while decreasing the maintenance costs at the same time. In cooperation with project partners, the research institute from Hannover, Germany, has developed a sensor system which continuously monitors the condition of the marine gearbox, thus preventing breakdowns. Special feature: the monitoring system works wirelessly and energy-autonomously. The required electrical power is generated where it is needed – directly at the sensor.
As well as cars need to be certified regularly (in Germany by the TÜV – Technical Inspection Association), ships need to be inspected – if the powertrain stops...
When an earthquake hits, the faster first responders can get to an impacted area, the more likely infrastructure--and lives--can be saved.
The Atlantic overturning is one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards. Also known as the Gulf Stream system, it is responsible for the mild climate in northwestern Europe.
Scientists now found evidence for a slowdown of the overturning – multiple lines of observation suggest that in recent decades, the current system has been...
Because they are regularly subjected to heavy vehicle traffic, emissions, moisture and salt, above- and underground parking garages, as well as bridges, frequently experience large areas of corrosion. Most inspection systems to date have only been capable of inspecting smaller surface areas.
From April 13 to April 17 at the Hannover Messe (hall 2, exhibit booth C16), engineers from the Fraunhofer Institute for Nondestructive Testing IZFP will be...
25.03.2015 | Event News
19.03.2015 | Event News
17.03.2015 | Event News
26.03.2015 | Trade Fair News
26.03.2015 | Trade Fair News
26.03.2015 | Life Sciences