Biomass and aerial productivity of Austrocedrus chilensis forests in Río Negro, Argentina.

The aim of this study was the determination of biomass and aboveground productivity in a monospecific forest of Austrocedrus chilensis, and to assess the effects of structural differences on merchantable products yield. Three stands of secondary forests (R1, R2, and R3) were studied in the Reserva Forestal Loma del Medio-Río Azul, in the vicinity of El Bolsón, Rio Negro Province. The stands were full stocked mature forests showing differences in structure. Three-500 to 1000 m2 circular plots were located in each stand. Size-class frequency distribution was analysed. Biomass was assessed by dimensional analysis, and productivity was estimated as the sum of litterfall and the biomass current annual increment. The three stands did not showed significant differences in total or plant compartments biomass, but they differed in density and size frequency distribution. The structural differences on density, mean quadratic diameter and dominant height were not expressed in noticeable productivity differences (7.2, 5.9 and 6.8 Mg.ha-1.yr-1 for R1, R2 and R3 respectively). However, there were significant differences in merchantable wood products yield, whose value is dependent in size, with 80% and 38% less product volume in R1 and R2 than in R3.

Key words: Dimensional analysis, structure, growth, ciprés de la cordillera.