Biomass of Pinus Resinosa in Relation To Potassium Nutrition

Abstract

Nineteen plots ranging in tree age from 29 to 32 years and comprising part of an extensive fertilizer trial on a potassium-deficient site were examined. The most recent potassium additions were made at least 12 years earlier, and a period of stable growth response reached. Net annual bolewood accumulation per hectare in potassium-deficient stands varied from 1.47 metric tons at 2000 stems/ha to 0.84 metric tons at 10,000 stems. Near optimum potassium additions increased net annual bolewood accumulation by 2.7 metric tons/ha. Net annual bole bark accumulation per hectare was 0.23 metric tons in potassium-deficient stands and an additional 0.43 metric tons in potassium-treated plots. Increased branch production following additions of potassium was offset by earlier mortality so that branch biomass was approximately constant irrespective of potassium status. Annual needle production varied from year to year but was not affected by potassium supply. Loss of potassium-deficient needles occurred mainly in the third and fourth years. Stands with added potassium kept needles for about an additional year and carried a total needle mass 2.9 metric tons/ha greater than potassium-deficient stands. Increased stocking significantly decreased stand biomass of 1-year-old needles, total needles, and live branches. Forest Sci. 16: 154-159.