Architecture of the skeletal root system of 40-year-old Picea abies on strongly acidified soils in the Harz Mountains (Germany)

Abstract

Altogether 15 root systems, five at each of three plots (north- and south-facing slopes and plateau), of 40-year-old Picea abies (L.) Karst. trees with different symptoms of forest decline were excavated down to a root diameter of 0.5 cm. The object was to investigate the variability of root morphology and to assess the influence of environmental variation on the architecture of the woody root system. For each tree, total height, diameter at breast height, and needle and twig biomasses were determined, and for each root system, biomass, growth, length, cross-sectional area, number and initial direction of branches, and branching forms were determined. The differences in many of the wood parameters within and between the plots were relatively few, so that forest decline symptoms determined at the crown could not be sufficiently related to the root system architecture. The results suggest a small influence of microsite conditions on the structural root systems, an influence of stand density on root distribution and soil exploitation, and a functional difference between horizontal and vertical roots that points out the importance of extensive long vertical roots, which insure a sufficient water and nutrient uptake.