What was done
Open-top chambers maintained at atmospheric CO2 concentrations of 350 and 700 ppm were erected upon a regenerating oak-palmetto scrub ecosystem in Florida, USA, to study the effects of elevated CO2 on productivity and growth in this specialized community.  This paper reports the effects of a doubling of the air's CO2 content on fine root length and distribution within the ecosystem, which is nutrient-poor and often water-stressed.

What was learned
Elevated CO2 increased fine root length densities by 63%, while enhancing the distribution of fine roots at both the soil surface (0-12 cm) and at a depth of 50-60 cm.

What it means
The findings of this paper indicate that oak-palmetto scrub ecosystems will likely exhibit enhanced fine root growth as the air's CO2 content continues to increase, in spite of their nutrient-poor and often water-limited soils.  In this regard, it is interesting to note that elevated CO2 will likely increase the distribution of fine roots near the soil surface, where the greatest concentrations of nutrients are located, and at a depth that coincides with the upper range of this specific site's water table.  Thus, future increases in the air's CO2 concentration will likely increase plant growth in this ecosystem by enhancing fine root development, which should increase the acquisition of soil nutrients and water needed to support enhanced biomass production.