By Scout Nelson
A decades-long field study in Minnesota has uncovered the harmful effects of rising carbon dioxide (CO2) and nitrogen pollution on grassland biodiversity. While it's well known that nitrogen pollution reduces plant species richness, scientists have struggled to determine whether rising CO2 levels exacerbate this effect.
University of Minnesota researchers began their study in the 1990s at the Cedar Creek Ecosystem Science Reserve to address this knowledge gap. Over more than two decades, the researchers manipulated CO2, nitrogen, and plant diversity across more than 100 grassland plots, analyzing how these factors influence species richness.
Their findings revealed that rising CO2 worsens nitrogen pollution’s impact on biodiversity. "If rising carbon dioxide generally makes the negative impacts of nitrogen deposition on plant diversity even worse, as observed in our study, this bodes poorly for conservation of grassland biodiversity worldwide," said Peter Reich, the study’s lead author.
In the early years of the study, nitrogen reduced species richness by 13% under ambient CO2 and only 5% under elevated CO2. However, in the final years, nitrogen reduced species richness by 19% under elevated CO2—nearly tripling the losses compared to the earlier period.
These losses were primarily due to increased competition for light, a trend that will likely affect grasslands worldwide. With dominant species thriving under higher nitrogen and CO2 levels, smaller species struggle to survive in shadier conditions.
This research, supported by the National Science Foundation and the hard work of over 200 students, highlights the urgent need for action to protect grassland ecosystems in the face of climate change.
Photo Credit:minnesota-department-of-agriculture
Categories: Minnesota, Energy, General