Relationships between forest tree species, stand production and stand nutrient amount

Abstract

Data from the literature concerning stand aerial biomass, stand nutrient amount (i.e. N, P, K, Ca and Mg) of four major forest tree species of the temperate area were compiled in order to propose simple general relationships to quantify nutrient depletion associated with biomass harvesting. The objectives was to identify the tree species effect on nutrient loss through biomass removal. Mean weighted nutrient concentrations of aerial biomass decreased rapidly until the maximum current annual increment of stands was reached (adult stands''); the concentration then became more or less constant. For adult stands, linear relations existed between aerial biomass and their nutrient amount. Using total aerial biomass (TAB) or stem biomass including bark (SBB) as references against the corresponding nutrient amount showed: i) that correlation coefficients were higher in the latter case, ii) that nutrient amount per unit of biomass was lower for SBB than for TAB, and iii) that these relations were species-dependent. For a same SBB, species were ranked as follows: mean concentration of N and K, European beech > Douglas fir = Norway spruce = Scots pine; Ca, European beech = Norway spruce $geq$ Scots pine $geq$ Douglas fir; Mg, European beech $geq$ Scots pine $geq$ Norway spruce $geq$ Douglas fir. For P, no significant difference was found for the tested species. The relationships between biomass and nutrient amount can be easily used by foresters to quantify the nutrient amount exported from a site during both thinning and harvesting operations, as well as the nutrients which remain in the logging residues left on the site and which will slowly yield available elements to the new plantation or the naturally regenerated stand.