The global vegetation might be getting a boost from increasing levels of carbon dioxide, but that doesn’t mean it is a good thing at all. The new growth is like junk food for the little creatures such as grasshoppers and other insects that end up eating plants.
Researchers have long acknowledged that the extra CO2 would drive a raise in biomass. The plants, however, reach the same blend of nitrogen, potassium, phosphorus, and other minerals in the soil, so the extra increase ends in something known as nutrient dilution.
How the Plants Influence the Ecosystem
A team of researchers from the US, led by Ellen Welti, hypothesized that plant-consuming insects, many of them have a nutrient-scarce diet, would suffer if what they eat become less nutritious. Researchers examined two decades of data on grasshoppers from a Kansas prairie and discovered something quite alarming.
They found that insect numbers dropped 2.1-2.7 %/year, with lower plant nutrients estimating for almost a quarter of that. The Konza Prairie was chosen due to its extensive data set, but also, as the native tall grasses were uninfluenced by pollution or urban expansion.
The biomass itself grew, increasing up to 60 percent between 1985 and 2016. Though, over decades, ass layers concentrations of nitrogen dropped 42 percent, potassium 54 percent, phosphorus 58 %, and sodium 90 percent, according to the new research.
“We know from a lot of work on grasshopper nutrient needs…that grasshoppers are very sensitive to changes in plant nutrient content,” stated Dr. Welti.
Belinda Medlyn, from the Western Sydney University, explained that the results were correlational, and there’s still potential for some other things to be going as well. So, the modification in nutrient content and plant biomass were, as Prof. Medlyn stated, “too large to be attributable to CO2” – regarding carbon dioxide concentrations that had increased almost a fifth between 1980 and 2015.