Effects of thinning and nitrogen fertilization on growth of Scots pine trees: total annual biomass increment, needle efficiency, and aboveground allocation of biomass increment

• Published in: Canadian Journal of Forest Research
• Main Author: Valinger, Erik
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1993
• Subjects: Ecology; Forestry; Global and Planetary Change; Northern Sweden
• Online Access: http://dx.doi.org/10.1139/x93-204; http://www.nrcresearchpress.com/doi/pdf/10.1139/x93-204

The effects of thinning and nitrogen fertilization, singly and in combination, on growth of 45-year-old Scots pine (Pinussylvestris L.) trees in northern Sweden were examined for 5 years after treatment. Annual examination of trees determined height growth, diameter growth, crown development, annual biomass increment, aboveground biomass allocation, and needle efficiency in relation to treatments. Nitrogen fertilization increased total dry matter production. The combination of thinning and nitrogen fertilization increased total dry matter production per tree more than the additive effects of thinning and nitrogen fertilization singly. Dry matter production per hectare was increased by nitrogen fertilization. Needle efficiency, i.e., total annual aboveground biomass production per unit of needle mass, was also increased by nitrogen fertilization. The increased aboveground production after nitrogen fertilization resulted from both an increase in biomass of needles and from the increased needle efficiency. The allocation pattern indicated that an increased production of stemwood was a result of a larger biomass of needles. An increase in cone production of the control trees was associated with a decrease in needle efficiency.