Root biomass changes after drainage and fertilization of a low-shrub pine bog

Abstract

The stump and root systems of Scots pine (Pinus sylvestris) and field-layer vegetation were sampled before (1984) and three growing seasons after drainage and fertilization (1987) of a low-shrub pine bog. Average below-ground biomass of the field layer was 548 gDW m−2 in 1984, with no significant treatment effects during experimentation. The stump-plus-root biomass of the pine stands was 1464 gDW m−2 in the virgin state, and had increased to 1854 gDW m−2 three years after the NPK-fertilizer treatment. The distribution over fractions also changed with this treatment. The fraction of fine roots (ϕ 10 mm) was improved. The observed changes in root biomass and structure are explained as strategic adaptations to altered hydrological and nutritional circumstances in the root zone after drainage and fertilization.