Carbon and nutrient stocks in mature Quercus robur L. stands in NW Spain

In the present study, the distribution of C and nutrients in biomass (above- and below-ground) and soil were estimated in native Quercus robur stands in NW Spain. This information can be used to design future strategies to preserve and improve these forests, which are subjected to severe degradation as a consequence of poor management and fire damage. Biomass equations for tree components were fitted simultaneously using the data corresponding to 31 trees felled in 4 representative mature stands. The C accumulated in aerial biomass, roots, litter layer and mineral soil made up 40, 10, 8 and 42% respectively, of the C in the whole forest system. Tree biomass contained higher amounts of macronutrients than the available reserves in the soil. Stem wood was the major tree compartment for most nutrients, with the exception of Ca, which was mainly accumulated in stem bark. In comparison with commercial forest plantations in the region, particularly high amounts of nutrients were accumulated in the litter layer because of the high amounts of litterfall and higher foliar concentrations of nutrients.