So plants growing vigorously with more plentiful carbon dioxide and warmer conditions can afford to divert less effort to protecting foliage from consumers – it’s easier to grow more. How does that indicate a problem?
Paleontologists and biologists reported an analysis of insect damage to Eocene fossil plants that has implications for what may happen as a result of present day global warming in the open access peer reviewed journal Public Library of Science on July 18, 2012.
Samples of insect-feeding damage on the two middle Eocene plant groups from the Messel and Eckfeld sites in Germany were examined from specimens from the Messel oil shale housed at the Senckenberg Forschungsinstitut und Naturmuseum, at Frankfurt am Main, Germany and from Eckfeld housed in the collections of the Naturhistorisches Museum Mainz/Landessammlung für Naturkunde Rheinland-Pfalz in Mainz, Germany.
The Eocene was a period of exceptionally warm temperatures. The Messel site date to 47.8 million years ago and the Eckfeld site dates to 44.3 million years ago. A total of 16,082 plant specimens were examined and rated for insect damage.
Insect feeding on evergreen species increased dramatically during the Eocene time period. The researchers attribute the increase to a 2.5-fold increase in atmospheric CO2 that overwhelmed evergreen antiherbivore defenses. The Messel samples show more damage than the Eckfeld samples because the levels of CO2 and the insect behavior caused by the levels of CO2 had decreased in the five million year time span that separates the fossils from the two sites.