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The effects of fertilizer treatment on the soil nutrient concentrations, biomass production and nutrient consumption of Salix x dasyclados and Salix ‘Aquatica’ were studied in five experiments on three cut-away peatland sites in western and eastern Finland during three years. Factorial experiments with all combinations of N (100 kg ha–1 a–1), P (30 kg ha–1 a–1) and K (80 kg ha–1 a–1) were conducted. The application of P and K fertilizers increased the concentrations of corresponding extractable nutrients in the soil as well as in willow foliage. N-fertilization increased foliar nitrogen concentration. An increase in age usually led to decreases in bark and wood N, P and K concentrations and increases in bark Ca concentrations. N-fertilization increased the three-year biomass yield 1.5–2.7 times when compared to control plots. P-fertilization increased the yield only in those experimental fields whose substrates had the lowest phosphorus concentration. K-fertilization did not increase the yield in any of the experimental fields. The highest total biomass yield of NPK-fertilized willow after three growing seasons, 23 t ha–1, was distributed in the following way: wood 42%, bark 19%, foliage 17%, stumps 6% and roots 16%. As the yield and stand age increased, more of the biomass was allocated in above-ground wood. Three-year-old stands (above-ground biomass 18 t ha–1) contained as much as 196 kg N ha–1, 26 kg P ha–1, 101 kg K ha–1, 74 kg Ca ha–1 and 37 kg Mg ha–1. By far the highest proportion of nutrients accumulated in the foliage. The bark and wood contained relatively high proportions of calcium and phosphorus respectively. With an increase in age and size, the amount of nitrogen and potassium bound in one dry-mass ton of willow biomass decreased while that of phosphorus remained unchanged.

For biomass forestry in the inland parts of southern and central Finland, the obvious choice of willow species is Salix myrsinifolia. However, selection of clones of indigenous species has not yet been completed and more research and selection is needed. In the Piipsanneva old peatland trial, indigenous species of willow, mostly clones of S. myrsinifolia and S. phylicifolia, were compared in terms of biomass production, coppicing, height growth and diameter distributions. In this trial, the mean annual biomass production was not particularly high; more important results were attained in the ranking of clones. This trial strengthens the hypothesis that, over the long term, the biomass production of S. myrsinifolia is higher than that of S. phylicifolia. It was supposed that behind the highest yield there was a clone with uniform quality, one whose diameter distribution would be narrow and positively skewed. Comparisons of parameters of Weibull functions showed that the distributions of the best clones were wide, indicating that those clones use the whole growth space better than these with narrow distribution.

Crown characteristics and the distribution of three yearsâ (1986â88) biomass production of 20 pendulous Norway spruce ( f. (Lawson) Sylvén) trees with heritable narrow crown and 15 normal-growned spruces ( (L.) H. Karst.) were studied in a 19-year-old mixed stand.Picea abiespendulaPicea abies-1-1

The development of shoot number and shoot properties was examined in successive shoot cohorts of young widely-spaced Scots pine trees ( L.) growing in a progeny trial. This was accomplished by reconstructing the branching process of the trees over a period of five years, from tree age 4 to 8. During this time the number of shoots in successive shoot cohorts increased rapidly, while at the same time the mean shoot length decreased. The decrease in shoot lengths from older to younger shoots was accompanied by a decline in the bifuraction frequency of the shoots. In general, rapid changes occurred in the branching characteristics during the yearly development of the trees. The variation in the branching characteristics was reflected in the development of the architecture and biomass production of the trees.Pinus sylvestris