Marsden et al., 2008. Relating coarse root respiration to root diameter in clonal Eucalyptus stands in the Republic of the Congo.

Marsden, C., Nouvellon, Y., Epron, D., 2008. Relating coarse root respiration to root diameter in clonal Eucalyptus stands in the Republic of the Congo. Tree Physiology 28, 1245-1254.

Abstract

Root respiration is an important component of the carbon balance of a forest ecosystem. We measured CO₂ efflux of excised fine roots and intact coarse roots in 3-, 4- and 13-year-old Eucalyptus stands in the region of Pointe-Noire, Republic of the Congo. A transportable and adaptable closed chamber gas exchange system directly measured CO₂ efflux of roots from 0.5 to 32 mm in diameter. Fluxes were corrected for measurement system leaks and normalized to a reference temperature of 30 °C. Mean fine root respiration rates at the reference temperature varied between 8.5 and 10.8 μmol CO₂ kg⁻¹ s⁻¹ depending on the stand. Coarse root respiration was strongly negatively correlated to root diameter. We propose a model based on a radial gradient of respiratory activity within the root to simulate the exponential decrease in respiration with diameter. Although many sources of uncertainty in the measurements remain, as discussed in this paper, these results provide a basis for scaling up organ-level root respiration measurements to the tree and stand levels.