Aboveground biomass and nutrient content of five Douglas-fir stands in France

Despite great interest shown in assessing nutrient removal by forest harvesting, little information is available concerning biomass and nutrient accumulation in French Pseudotsuga menziesii (Mirbel) Franco stands. Five even-aged Douglas-fir stands from three age classes (26–29, 36, and 54 years of age) were selected in several large wood production areas. Regression equations were developed for separate estimates, at the stand level, of stemwood, stembark, branchwood (wood+bark), needle biomass and nutrient contents (N, P, K, Ca, Mg). Soil pools (0–100 cm total N, BaCl2 extractable cations and Dyer’s extractable P contents) were quantified for comparison with the corresponding tree nutrient data. For all stands and elements, mean nutrient concentrations increased in the order stemwood⪡stembark<branchwood⪡needles. Scheffe’s tests indicated significant differences (P<0.05) between stands for most elements and components. The magnitude of the effect and the corresponding stand groupings, however, depended both on the elements and the components. The comparison between restricted and full regression models showed that no common biomass or nutrient content tables could be obtained at P