An ecoregional model for estimating volume, biomass and carbon pools in maritime pine stands in Galicia (northwestern Spain)

Stand density management diagrams, including information about stand volume, stand aboveground biomass, stand stem biomass and carbon pools, were developed for maritime pine stands in Galicia, by applying biomass regression functions and carbon estimates to data from a network of 266 plots located throughout Galicia. The models were constructed on the basis of five equations that were fitted simultaneously using the full information maximum likelihood procedure. The first equation relates quadratic mean diameter to the number of stems per hectare and dominant height. The next three equations relate stand volume, stand aboveground biomass, and stand stem biomass to quadratic mean diameter, number of stems per hectare and dominant height. The last equation relates carbon pools in stand aboveground biomass to stand aboveground biomass. Evaluation of the equations used to develop the diagrams, by the non-linear extra sum of squares method and the Lakkis–Jones test, revealed differences for the two ecoregions defined for the species in Galicia. Different stand-level models and the associated diagrams for stand volume, stand aboveground biomass, stand stem biomass, and carbon pool estimation were therefore developed for each ecoregion.