Effects of thinning and nitrogen fertilization on stem growth and stem form of Pinus sylvestris trees

Abstract

The effects of thinning and fertilization, both singly and in combination, on the growth of 45 year old Pinus sylvestris trees, were studied in northern Sweden for five years after treatment. Based upon annual examination of trees for height and diameter growths, the radial, height and volume increments of the stems in relation to treatments were estimated. Thinning was found to increase stem radial growth after one year, while increased growth after fertilization appeared the second year. Thinning promoted lower bole growth, while fertilization increased upper bole growth. Thinning decreased height growth and fertilization increased height growth in the first year with associated increased volume increment. An increased volume growth for thinned trees was not found until the third year after treatment. Neither treatment caused changes in the length of the seasonal growth response or in the phenology of growth.