Change in critical grasslands diminishing cattle production

August 18, 2014

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.

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. trees and shrubs and grasslands Download Full Image

“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 1 percent leads to a 2 percent loss in livestock production.” And, woody-plant cover in North America increases at a rate between 0.5 and 2 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 levels of economic development.

Surprisingly, the presence of trees explained a larger fraction of livestock production in Argentina than in the United States.

“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 their study will be used to inform discussions as policymakers 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

Assistant Director of Media Relations, ASU Knowledge Enterprise


Keep safety in mind during school year

August 18, 2014

Starting a new academic year is a great time to make friends, learn new subjects and keep safety in mind.

The ASU and Tempe Police Departments are involved in several efforts this year that emphasize student safety. Both departments will conduct a joint awareness campaign during the first weeks of school to enforce traffic laws and alcohol violations. ASU students Download Full Image

“We hope that ASU students have a safe and productive academic year. The ASU and Tempe Police Departments will work closely together to educate students about safety issues,” said Michael Thompson, acting ASU Police Department chief.

ASU Police personnel participate in many back-to-school activities that welcome students to campus, provide safety information and give students a chance to meet their police department. These include new student orientations, international student orientations, move-in, Welcome Week, the off-campus information fair with the Tempe Police Department and Passport to ASU. The department holds mandatory student safety meetings for students living on campus at the beginning of the school year, and they host on average more than 100 events per year where officers educate students about alcohol.

The ASU Police Department is also focusing this year on preventing sexual violence in conjunction with the Tempe Police Department. As the first university police department in Arizona to sign the national “Start by Believing” proclamation in support of victims of sexual violence, the ASU Police Department will work with Tempe police, university departments that serve students and ASU students on this effort.

Traffic and pedestrian safety is another high priority during the first weeks of school. High-traffic focus areas include University Drive and College Avenue, Apache Boulevard and College Avenue, and Apache Boulevard and McAlister Avenue. Traffic warnings will be provided during the first week. After that, tickets will be issued for violations.

Emergency information

Students, faculty and staff are encouraged to add or update their mobile numbers to receive ASU Alert text messages.

ASU Alert is used during major emergencies and incidents that greatly affect university operations. ASU Advisory is considered a tier below ASU Alert, and communicates situations that may not be life threatening and typically affect certain areas of a campus.

To provide or verify your mobile number, follow these steps:

• Visit to manage phone numbers.
• Select mobile as “Phone type.”
• Click “save” to add or update.

To modify Alert and Advisory subscriptions:

• Visit
• Click subscriptions on the left, then edit button next to the subscription.
• Click “save” when done.

More information may be found at

Keep your bike safe

September is the month when most bike thefts occur on and around campus, according to the ASU Police Department. It’s best to use two locks to keep your bike safe – a U-lock to secure the bike to a stationary object, and a cable lock to doubly secure it and lock the wheels to the frame.

Learn how to keep your bike safe by watching a video demonstrating how to properly secure it. In addition, ASU Police uses bait bikes equipped with GPS systems to catch thieves, and the department encourages students, faculty and staff to register bikes at

Safety tips

Additional basic safety tips that members of the ASU community should keep in mind:

• Call 911 in an emergency. Call boxes highlighted at the top by a “blue light” dial directly into an emergency communication center and can be used during any emergency. If you are using a cell phone, give your location.

• Lock your doors. Do not prop doors open. Warn others against leaving their doors open or unsecured.

• When going out, let others know what your plans are and where you will be so they know where to look for you if something should happen.

• Be aware of your surroundings.

• Don’t leave valuable items in your car.

• Properly secure your bike to an authorized rack.

• Watch for passing trains. Never trespass on the tracks or jaywalk across the rails.

• Don’t give personal information to someone you don’t know.

• If someone demands your property, give it to them and immediately contact the police.

• If you are traveling at night, use the buddy system.

A free safety escort service is available on the Tempe campus. Call 480-965-1515 to arrange for an escort. For an escort on another campus or after hours of operation, call ASU Police at 480-965-3456, and an officer or police aide will provide an escort.

Additional information about staying safe at home, at parties, while driving and in other situations may be found at

More information about the ASU Police Department is available at