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Amount of boron in Norway spruce stands in eastern Finland

Tamminen, Pekka, Saarsalmi, Anna, Kukkola, Mikko
Forest ecology and management 2012 v.269 pp. 92-98
Picea abies, boron, boron fertilizers, ecosystems, harvesting, mineral soils, nitrogen, stems, trees, Finland
The aim of this study was to determine the amount of boron in three Norway spruce (Picea abies (L.) Karst) stands in eastern Finland, where boron deficiency is common. A further aim was to estimate the effects of logging-residue harvest on boron balance and the boron-to-nitrogen ratio on these sites. The data were obtained from a 30-year-old and a 62-year-old healthy spruce stand as well as from a 35-year-old spruce stand with boron deficiency and growth disorders. Altogether 2.1 and 2.4kgha⁻¹ boron, respectively, were bound in trees+organic layer+0–10cm mineral soil layer in the two healthy stands, and 0.9kgha⁻¹ in the boron deficient stand. For the amount of boron in the healthy stands the trees made up 43% and 49%, respectively, and in the boron deficient stand 38%. Stems contained 30% and 40%, respectively, of the boron in trees in the healthy stands and 37% in the boron-deficient stand. Only 11–13% of the tree boron was in the needles. The amount of nitrogen bound in the ecosystem studied was 2.1 and 2.5Mgha⁻¹, respectively, in the two healthy stands and 3.0Mgha⁻¹ in the boron deficient stand. In the ecosystem the trees contained 21–29% of the amount of nitrogen. Stems contained 14–24%, respectively, and needles 26–36%, respectively, of the nitrogen in the trees on the studied stands. In stem-only harvestings, relatively more boron than nitrogen would be removed from a site. In the boron-deficient stand, boron fertilisation for 3years nearly doubled the amount of boron in the ecosystem. Only 38% of the fertiliser boron (2kgha⁻¹) was found in the ecosystem components studied.