Elevated atmospheric CO₂ increases fine root production, respiration, rhizosphere respiration and soil CO₂ efflux in Scots pine seedlings

Abstract

Abstract In this study, we investigated the impact of elevated atmospheric CO 2 (ambient + 350 μmol mol –1 ) on fine root production and respiration in Scots pine ( Pinus sylvestris L.) seedlings. After six months exposure to elevated CO 2 , root production measured by root in‐growth bags, showed significant increases in mean total root length and biomass, which were more than 100% greater compared to the ambient treatment. This increased root length may have lead to a more intensive soil exploration. Chemical analysis of the roots showed that the roots in the elevated treatment accumulated more starch and had a lower C/N‐ratio. Specific root respiration rates were significantly higher in the elevated treatment and this was probably attributed to increased nitrogen concentrations in the roots. Rhizospheric respiration and soil CO 2 efflux were also enhanced in the elevated treatment. These results clearly indicate that under elevated atmospheric CO 2 root production and development in Scots pine seedlings is altered and respiratory carbon losses through the root system are increased.