Roots of Norway Spruce Trees Growing in CO2-Enriched Air
Pokorny, R., Tomaskova, I. and Marek, M.V. 2013. Response of Norway spruce root system to elevated atmospheric CO2 concentration. Acta Physiologiae Plantarum 35: 1807-1816.
The three researchers report that the above-ground biomass of the Norway spruce saplings rose by about 12% in response to the doubling of the atmosphere's CO2 concentration, while their below-ground biomass rose by a more-than-three-times-larger 37%. Interestingly, none of this growth enhancement occurred in primary roots. Instead, it all occurred in secondary and fine roots.
As for the significance of their findings, Pokorny et al. write that "the finest roots showed the highest positive growth stimulation under elevated CO2 conditions," and they note that this phenomenon leads to a "larger root absorbing area per tree," which in turn leads to "better tree water supply under elevated CO2," with its attendant "higher chance to survive dry periods." And, of course, a larger root-absorbing area per tree also results in more nutrients being absorbed by the trees, which enables them to better cope under stressful environmental conditions.