UNIVERSITY PARK, Pa. — A Penn State plant scientist has received a $650,000 grant from the U.S. Department of Agriculture to lead a team studying how changes in temperature associated with climate change affect the establishment, persistence and performance of perennial forage crops and their associated weedy plant communities in the U.S. Northeast.

Carolyn Lowry, assistant professor of plant science in the College of Agricultural Sciences, will use the competitive four-year award from USDA’s National Institute of Food and Agriculture to fund research to determine the degree to which forage-management practices — such as variety selection and harvest frequency — may reduce or worsen these effects.

“We are focusing on how farmers can manage for climate change, specifically how they can manage forage stands to take advantage of warming winters, but also ensure plants survive in response to increasing winter weather variability,” she said. “One of the things that we’re seeing is repeated warm spells in winter followed by frigid periods — and that can stress out overwintering plants like alfalfa.”

Perennial forage crops that are cold-sensitive are especially vulnerable to winter weather variability and may experience greater incidences of winterkill because of decreased snow cover and warm spells followed by hard frosts in early spring, she explained. Poor winter survival is one of the leading impediments to reliable alfalfa stand establishment.

Winter injury can decrease yields and, when severe, can necessitate replanting. The management practices that will allow farmers to realize greater yields in response to warming winter temperatures — such as increasing the number of harvests per year and switching to less dormant alfalfa varieties — also are likely to leave alfalfa plants more prone to winter injury.  

The importance of forage crops to agriculture in the Northeast cannot be overstated, according to Lowry. With an economic value of greater than $800 million annually, forages are the backbone of the region’s livestock industries, the largest of which is dairy. Research aimed at evaluating how warmer and more variable weather affects the productivity and stability of perennial forage crop systems is essential to determining optimal forage-management strategies for adapting to the changing climate.

The research will have three major objectives: evaluate the effect that forage management — planting different varieties varying in fall dormancy and forage-harvest frequency — has on alfalfa’s winter injury and survival, as well as forage yield, weed suppression and community composition in response to climate manipulations; characterize the effect of climate manipulations on weed seedbank dynamics and emergence timing; and quantify the extent to which environmental variables within climate manipulations and forage-management treatments predict forage and weed responses.

The project is innovative and complex. It will use hexagonal open-top chambers to manipulate temperature conditions within the plots.

“Using hexagonal open-top chambers is an effective and affordable method to simulate increasing temperatures and increasing weather variability in the field to understand better the impacts climate change may have on perennial forage crops,” Lowry said. “And no one has yet investigated how warmer temperatures and winter weather conditions may affect weed seed persistence in the soil. Our project will provide insight into how climate change will influence perennial forage-weed interactions, as well as weed population and community dynamics more broadly.”

To learn how both increasing temperatures and more frequent winter temperature fluctuations affect perennial forage production systems in the Northeast, researchers will conduct two separate, but complementary, field experiments in Pennsylvania and New Hampshire, both of which will use the hexagonal open-top chambers to passively increase air and soil temperature in a perennial alfalfa and orchardgrass crop.

The forage management experiment will examine the interaction of climate manipulations with forage management — varying harvest frequency and alfalfa varieties differing in fall dormancy.

The second component of the research, called the auxiliary weed experiment, will evaluate how climate manipulations affect weed seedbank dynamics within a perennial forage such as an alfalfa and orchardgrass crop, which is commonly planted by farmers in the Northeast.

Research team members include Luis Duque, assistant research professor in storage root physiology at Penn State, and Richard Smith and Alix Contosta at the University of New Hampshire.