Vekst i unge furu- og granbestand paa groeftet og gjoedslet torvmark.
1985
Braekke F.H.
Growth and development of Scots pine and Norway spruce up to 31 years of age are described. Norway spruce was planted on soligenous peat, where potassium and phosphorus fertilization was required for good growth. The Scots pine experiment was established on ombrogenous peat, where also N-fertilizer improved growth. Both fields have a climatically favourable location near the coast. The fertilized pine plots were rather densely stocked (more than 5000 trees/ha), and developed severe instability at age 18 to 20 years and top height 7.3 m. A strong thinning, which reduced the number of trees from about 5050 to 3130, and re-fertilization, stabilized the stands within two to three years. Despite a very high tree number also in the spruce stands, this problem was not present. Total production to 31 years of age was close to 200. Mean annual increment in the last period of revision (1982-83) was 6.3 cbm o.b./ha without fertilization and 14.3 cbm o.b./ha with fertilization. Total yield on fertilized spruce plots was 166 cbm o.b./ha and mean annual growth 16.7 cbm o.b./ha (1981-82). This corresponds to site index F23.0 and G23.0 with mean annual increment at 11-12 cbm o.b./ha over a rotational period of 65-70 years. Severe pine shoot beetle attack (Tomicus spp.) in 1977 gave growth depression. Over a three-year-period the fertilized pine plots lost at least 11 cbm o.b./ha in yield or about one year's production.
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