Background
The authors write that "the productivity and vitality of forest trees depend on their access to soil resources," and that "in forest ecosystems mycorrhizal associations constitute the interface between nutrients in the soil solution and the uptake organs of trees." As a result, the symbiotic association that exists between ectomycorrhizal (ECM) fungi and the fine-roots of trees is extremely important to the health and productivity of earth's forests.

What was done
The twelve-member team of researchers (hailing from the Czech Republic, Finland, France, the Netherlands, Norway, Poland, the Slovak Republic and Slovenia) evaluated, by means of a literature review and subsequent meta-analysis, the overall magnitude of the effect of an approximate doubling of the atmosphere's CO2 concentration on the characteristics of the ECM fungal mantle that typically covers portions of the fine-roots of earth's trees.

What was learned
Cudlin et al. report "there was a significant positive effect of elevated CO2 on ECM parameters," with the ECM fractional cover of fine-roots increasing by 19% and the number of ECM root tips increasing by 32%. In addition, they found that "the response in long-term experiments was significantly higher than that in experiments of shorter duration," which suggests, as they describe it, that "this response is not transient but persistent and even increases over time."

What it means
As the air's CO2 content continues to rise, we can expect that the ECM fungal mantle that covers portions of the fine-roots of earth's trees will become even better established than it is currently, with the result that (1) the planet's forests will likely have better access to the nutrients they need and (2) they will therefore be better able to take advantage of the increased potential for growth that is provided by the increase in rates of needle and leaf photosynthesis that are typically induced by elevated concentrations of atmospheric CO2.