Grasshopper numbers at a tall grass prairie have declined ca. 2% per year. Ellen Welti leads in identifying a likely culprit: increasing CO2 is diluting plant nutrients, making each bite less and less nutritious over the years. This open access paper at PNAS https://www.pnas.org/content/pnas/117/13/7271.full.pdf earned the 2020 finalist for the Cozarelli Prize for the best PNAS paper in the Environmental Sciences.
An intensive program of sweep netting at @KonzaLTER revealed 37% decline over 22 years. This decadal decline is similar to those found for butterflies, suggesting a common cause. Konza-a large preserve-isn’t destroying habitat or using pesticides. But…
Konza also harvests plants every season to measure production. We show over this time how grass production has ca. doubled. And with no corresponding added nutrients the concentration of nutrients is declining in dominant grasses: grasshopper food. Hence the Dilution Hypothesis.
We are left w the working hypothesis that 5-year fluctuations in climate combine with long-term accumulation of CO2 to reduce the capacity of this tall grass prairie to support a dominant herbivore. How common is Nutrient Dilution? And how do we fix it? Stay tuned.
Originally tweeted 9 March 2020