Effects of Climate Change on Pasture Production and Forage Quality

Why Study Climate Change and Pastures? Pastures cover more than 14 million hectares in the eastern half of the United States and support grazing animal and hay production while also contributing to the maintenance of overall environmental quality and ecosystem services. Climate change is likely to alter the function of these ecosystems. This manipulative field experiment evaluated the effect of warming and additional precipitation on forage production and quality. What Did We Do? We initiated a multi-factor climate change study, elevating air temperature (+3º C) and increasing growing season precipitation (+30% of long-term mean annual), in a central Kentucky pasture managed for hay production. Treatments began in May 2009 and have run continuously since. We measured the effects of warming and increased precipitation on pasture production, forage quality metrics, and for endophyte-infected tall fescue, ergot alkaloid concentrations. What Have We Learned? Effects of warming and increased precipitation on total yearly pasture production varied depending on the year of study; however, climate treatments never reduced production below that of the ambient control. Effects on forage quality metrics were relatively subtle. For endophyte-infected tall fescue, warming increased both ergovaline and ergovalinine concentrations (+40% of that in control ambient plots) throughout the study. These results indicate that central Kentucky pastures may be relatively resilient to future climate change; however, warming induced increases in ergot alkaloid concentrations in endophyte-infected tall fescue suggests that animal issues associated with fescue toxicosis are likely to be exacerbated under future climatic conditions. Future Plans We will continue this study for one more growing season and then destructively harvest it (in Fall 2013)