Jack Pine Biomass Accretion on Shallow and Deep Soils in Minnesota

Abstract

AbstractBiomass accretion and standing biomass of jack pine (Pinus banksiana Lamb.) were studied on sballow soils over three different bedrock types; granite, greenstone, and gabbro; and on deep till in northeastern Minnesota. The shallow soils were either Lithic Udorthents or Lithic Dystrochrepts and the deep soils were Typic Dystrochrepts. Individual tree biomass accretion was described by combining diameter‐age and biomass‐diameter relationships. At age 50, the mass of an average surviving tree on till would be 117 kg, and of trees growing on shallow soil over greenstone, granite, and gabbro would be 88, 68, and 57 kg, respectively. As an index of productivity, this ranking agrees with that of rock types based on site index (14.3, 11.2, 10.2, and 9.3 m at 50 years, respectively). Although these results imply differences in yield, the average overstory biomass did not differ between shallow soils, with an average of 81,000 kg/ha, compared to a significantly greater 147,000 kg/ha on the deep till. Stand biomass accretion was estimated by adjusting the relationship between stocking and age, and diameter and age, from a normal yield table to fit the present status of the sampled stands on each rock type. These data were then combined with a tree biomass‐diameter function, yielding a relationship between stand biomass and age for each rock type. The estimated biomass accretion was similar on shallow soils but greater mass occurs at any age on deep soils.