THE STRUCTURE OF FOREST STANDS IN VIRGIN AND MANAGED PEATLANDS - A COMPARISON BETWEEN FINNISH AND RUSSIAN KARELIA

This study investigated the changes caused by management, including dr ainage and thinnings, in peatland forest stand structure. Drained peat land sites in Finnish North Karelia were compared within the same type groups and nutrient status levels of virgin peatlands in the Republic of Karelia, the Russian Federation. The Variables studied, which depi ct stand structure variation, included: (1) the diameter of the median tree; (2) the range of sampled diameters; (3) the basal area of the s tand; (4) the estimated number of tree storeys; and (5) the number of the tree species. The number of tree storeys was determined through no n-parametric Kernel estimation. Over a long duration, management smoot hs the natural multi-modal structure of virgin peatland stocking by de creasing the variation in size-distribution. Management also changes t he natural tree species dynamics on peatland sites by providing a comp etitive advantage to the tree species, which adjust best to the change d growing conditions. These species begin to dominate the habitat and reduce the species diversity. The effect of recent thinnings and clean ing cuttings on the forest structure is dependent upon fertility of th e site and the stage of the forest stock at the moment of silvicultura l operation. Cleaning cuttings may have also an increasing effect on t he structural diversity of peatland forest stand. (C) 1997 Elsevier Sc ience B.V.