ARCHITECTURE OF THE SKELETAL ROOT-SYSTEM OF 40-YEAR-OLD PICEA-ABIES ON STRONGLY ACIDIFIED SOILS IN THE HARZ-MOUNTAINS (GERMANY)

Altogether 15 root systems, five at each of three plots (north-and sou th-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 variabil ity of root morphology and to assess the influence of environmental va riation on the architecture of the woody root system. For each tree, t otal height, diameter at breast height, and needle and twig biomasses were determined, and for each root system, biomass, growth, length, cr oss-sectional area, number and initial direction of branches, and bran ching forms were determined. The differences in many of the wood param eters within and between the plots were relatively few, so that forest decline symptoms determined at the crown could not be sufficiently re lated to the root system architecture. The results suggest a small inf luence of microsite conditions on the structural root systems, an infl uence of stand density on root distribution and soil exploitation, and a functional difference between horizontal and vertical roots that po ints out the importance of extensive long vertical roots, which insure a sufficient water and nutrient uptake.