MADISON – For farmers struggling against economic forces and doing everything they can to keep afloat, grassland biodiversity may be the last thing they want to worry about.
But expanding crops into grasslands to increase production could further jeopardize their operations’ profitability due to diminished yields, according to University of Wisconsin-Madison researchers. And these areas, while generally not well suited for growing crops, are important to the native biodiversity of the Midwest.
“Croplands are continuing to expand into grasslands and other natural areas at high rates – over a million acres per year are being converted,” says Tyler Lark, an assistant scientist in UW-Madison’s Center for Sustainability and the Global Environment.
In 2015, Lark and his collaborators in the lab of geography and environmental studies Professor Holly Gibbs published their first land-use analysis on cropland expansion, which found 7.3 million acres of primarily grasslands converted to farmland between 2008 and 2012.
In a new study, published last month in the journal Nature Communications, the researchers show that newly added croplands generated, on average, 10 percent less yield than existing cropland. By adding maps of habitat quality to the crop expansion analyses, they also found the cropland-converted grasslands to be areas extremely important to wildlife.
For example, Lark says these areas support three times more milkweed – a plant important to monarch butterflies – and also provide critical nesting access and breeding sites for birds.
“Even though these lands may not be prime for agricultural use, they’re really some of the most important and valuable wildlife habitat that exists in the U.S.,” Lark says. “We’re losing millions of milkweed plants each year due to cropland expansion, which puts land use change on the same order of magnitude as some of the other pre-eminent threats to monarchs.”