%0 Research article
%T Biomass and nutrition of naturally regenerated and coppiced birch on cutaway peatland during 37 years
%A Hytönen, Jyrki
%A Aro, Lasse
%D 2012
%J Silva Fennica
%V 46
%N 3
%R doi:10.14214/sf.48
%U https://silvafennica.fi/article/48
%X Biomass production and nutrient use of birch thickets with a mixture of  willow on a cut away peatland in southern Finland over a period of 37  years was studied. Dense, naturally regenerated 16-year-old birch stands  were cut down, fertilized with either wood ash (P 108 and K 339 kg ha<sup>–1</sup>) or PK fertilizer (P 50 and K 95 kg ha<sup>–1</sup>)  or left unfertilized. The biomass production of the coppiced stands and  one uncut stand was monitored for a period of 21 years. Soil nutrient  and foliar nutrient concentrations were analyzed several times during  the study period. Ash fertilization supplied more nutrients than PK  fertilization and increased the soil nutrient amounts more. The foliar  phosphorus concentration of birch on control plots indicated a severe  phosphorus deficiency which was removed by PK and ash fertilization.  Fertilization did not increase nutrient concentrations of the stem (wood  + bark) nor the amount of nutrients bound in the biomass. Two energy  wood rotations (16+21 years) produced 124–158 Mg ha<sup>–1</sup> of leafless, above-ground biomass altogether corresponding to 61–78 Mg ha<sup>–1</sup> of carbon. The highest biomass yield was achieved with a rotation of 37 years in the uncut stand (211 Mg ha<sup>–1</sup>). Corresponding values for mean annual increment (MAI) were 3.4–4.3 Mg ha<sup>–1</sup> and 5.7 Mg ha<sup>–1</sup>.  This study shows that the length of the rotation for birch in energy  wood production should be longer than 21 years. PK and ash fertilization  increased the biomass of coppiced 21-year-old birch by 23 Mg ha<sup>–1</sup> and 33 Mg ha<sup>–1</sup>, respectively.