Posted: Thursday, December 13, 2012 12:00 PM
By DOUG WARNOCK
For the Capital Press
'All things are interconnected and interdependent in time and space," said Fred Provenza, professor emeritus at Utah State University. Provenza was a featured speaker at the Range School during the 11th annual Quivira Coalition Conference in Albuquerque, N.M., last month.
"Landscapes are relationships among organisms that are adapting to change," Provenza said. To be effective, successful managers of grazing lands, we must understand which plants animals eat, the locations where they forage and how we can influence their grazing habits to optimize usage.
"Changes are happening all the time, so the only constant in life is change," he said. "Organisms decide what is relevant to them in the landscapes they inhabit. Life is a series of decisions." An organism's experience in its environment helps determine its structure.
Plant behavior differs according to the type of landscape in which it lives. In resource-poor areas, plants have low inherent growth rates and high levels of defense in order to survive. In more resource-rich areas, plants have relatively high growth rates and low levels of defense. The environment in which they live influences the chemical characteristics and content of toxins of the plants living there. The primary role of these secondary compounds or toxins in plants is to provide a defense for plant survival.
Plants respond to grazing according to how much tissue is removed (intensity), when it is removed (time) and how often it is removed (frequency).
Animal behavior is based on its consequences. Positive outcomes result in repeating an activity, while negative outcomes result in avoiding the activity. Response of animals to different foods is a result of both their genetic makeup and the environment in which they are living.
Plant palatability is more than taste. Higher nutrient content also increases the palatability of a plant. Animals will seek plants containing nutrients they need or desire.
Provenza cited several case studies where knowledge of behavior helped managers make significant changes in plant communities. In one, a sagebush-steppe landscape was improved through strategic grazing planning. The site had experienced an increase in sagebrush and a decrease in desirable grasses in recent years
The managers changed the timing of grazing and the stock density to impact the sagebrush population. Cattle and sheep were allowed to graze during the late fall and winter when the toxin content of the brush was lower. Supplemental energy and protein was fed to help the animals detoxify and to ensure adequate nutritional levels during the season of minimal plant growth. Higher stock density helped make a significant impact on the sagebrush. As a result of this management, sagebrush populations were decreased, while the number of desirable grasses and forbs was increased.
By understanding animals and their grazing behavior, we can be more successful in using them as a very positive tool to influence the composition and vigor of plant communities on our western landscapes.
Doug Warnock, retired from Washington State University Extension, lives on a ranch in the Touchet River Valley where he consults and writes on ranch management.