While higher levels of CO2 in the atmosphere can promote plant growth, the increase is having a negative effect on insect populations. While the increase in atmospheric CO2 is supplying plants with extra carbon that fuels growth, other nutrients such as calcium, potassium, zinc, and iron are being diminished. The resulting plant growth is less dense in nutrients, affecting animals and insects that rely on plants for food.
Nutrient dilution hypothesis
The effect of CO2 on plant nutrient levels is called the “nutrient dilution hypothesis” by researchers and its having an effect on insects. One group of researchers looked at more than 40 species of grasshopper in the Konza Prairie in Kansas to see the effect of changing plant nutrients on insect populations. Researchers have been collecting data from the Konza Prairie since the 1980s, providing a nearly 50-yearlong record on the grasses, insects, and animals that inhabit this ecosystem. In reviewing past and present data, researchers found that grasshopper populations are declining at a rate of 2% per year which parallels a decline in grassland nutrient levels.
Bruckerhoff, L. A., Connell, R. K., Guinnip, J. P., Adhikari, E., Godar, A., Gido, K. B., … & Welti, E. (2020). Harmony on the prairie? Grassland plant and animal community responses to variation in climate across land‐use gradients. Ecology, e02986. https://doi.org/10.1002/ecy.2986
Welti, E. (2020, March 9). Malnourished bugs: Higher CO2 levels make plants less nutritious, hurting insect populations. The Conversation. https://theconversation.com/malnourished-bugs-higher-co2-levels-make-plants-less-nutritious-hurting-insect-populations-133051