What was done
Working in a fire-maintained low-nutrient ecosystem at the Kennedy Space Center near Titusville, Florida, USA - which is dominated by two species of scrub oak (Quercus geminata and Q. myrtifolia) that account for more than 90% of the biomass at the site - and focusing on the abundance of a guild of lepidopteran leafminers that attack the leaves of myrtle oak (Q. myrtifolia), as well as various leaf chewers that also like to munch on this species, the scientists who performed the research described in this paper followed 100 marked leaves in each of sixteen open-top chambers (half of which chambers were exposed to ambient air and half exposed to air containing an extra 350 ppm of CO2) for a total of nine months, after which, in their words, "differences in mean percent of leaves with leafminers and chewed leaves on trees from ambient and elevated chambers were assessed using paired t-tests."

What was learned
The scientists report that "both the abundance of the guild of leafmining lepidopterans and damage caused by leaf chewing insects attacking myrtle oak were depressed in elevated CO2."  Specifically, they found that leafminer abundance was 44% lower (P = 0.096) in the CO2-enriched chambers compared to the ambient-air chambers, and that the abundance of leaves suffering chewing damage was 37% lower (P = 0.072) in the CO2-enriched air.

What it means
The implications of these findings are rather obvious: myrtle oak trees growing in their natural habitat will likely suffer far less damage from both leaf miners and leaf chewers as the air's CO2 concentration continues to rise in the years and decades ahead.