Land used for livestock grazing; referred to as rangeland in the western U.S. and pasture land in the eastern half of the country, encompasses over 584 million acres of non-Federal land and represents a very complex ecosystem.

While the intensity of the management of these lands differs from parcel to parcel, there is no doubt they all play a vital role in livestock production. However, little research has been conducted to determine the affect of climate change and rising amounts of atmospheric carbon on rangelands. With projections estimating a 2 degree Celsius increase in average global temperature and a rise in precipitation rates, the impact could be incredibly detrimental to the livestock industry.

Researchers at the Joint Global Change Research Institute in Maryland have reviewed almost a hundred laboratory studies and field experiments on various plant species found across the United States to develop an understanding of the effects climate change has had and will have in the future. Most of the studies were less than ten years old but some were from as far back as the 1980s. Publications under review had tested the effects of atmospheric carbon at the current levels of 380 parts per million to 760 parts per million.   

Lead author César Izaurralde stated, “One of the most important findings from this study is that pastures and ranges will respond quite differently depending on their regional location and their species makeup. Some plant species will grow more vigorously bathed in extra carbon dioxide, others will wilt in too-high temperatures. For some plants, precipitation amounts will likely be the deciding factor between successful growth or failure.”

Although the review and research conducted examined the effect of climate change on plants in the rangelands, the combined effect of grazing and climate change on the ecosystem was not reviewed.  Nor was the effect of higher temperatures and increased precipitation rates on non-plant species.

Nevertheless, Izaurralde assured that the review was just the first step, adding, "These are critical questions that we need to answer.  There is a need for holistic understanding of climate change impacts on pastures and rangeland ecosystems, including grazing regimes, mutualistic relationships, as well as changes in water, carbon, and nutrient cycling."

The complete results are available in the March/April 2011 issue of Agronomy Journal.

The full article is available for no charge for 30 days following the date of this summary. View the abstract at https://www.agronomy.org/publications/aj/abstracts/103/2/371.