Targeted Grazing By Cattle

Targeted grazing by sheep to control weeds, like our Vines

and Ovines project is becoming more popular, but did you know that cattle are also useful in targeted grazing? Researchers at Oregon State University have discovered that cattle, through targeted grazing benefit forest seedlings. Their work done on conifer plantations of Douglas fir and ponderosa pine used cattle to graze the competing understory. On those plantations the understory of predominately grasses compete with the seedling trees, retarding their growth.

In their study the researchers wanted to find out if by grazing cattle to reduce the common grass orchardgrass, that more soil moisture would be available to the trees.  They found that seedling water stress levels during spring and summer were similar in a cattle-grazed vs. ungrazed area, but in summer, water stress was reduced significantly in the grazed area. Soil water content was higher in the grazed area, especially at the 10-20 cm soil depth. End of season (July) orchardgrass root growth was reduced 18% and 15% with grazing. They concluded that repeated cattle grazing of orchardgrass reduced transpirational surface area and root growth sufficiently to increase soil water availability to seedlings. Thus, prescribed cattle grazing on conifer plantations can enhance seedling physiological status by acting as a regulator of above- and belowground competition.

Additional Reading

Karl, Michael G. and Paul S. Doescher. 1993. Regulating Competition on Conifer Plantations with Prescribed Cattle Grazing. Forestry Sci. 39(3):405-418.