Performance of planted and naturally regenerated seedlings in Picea abies-dominated shelterwood stands and clearcuts in Sweden

This study was focussed on regeneration of Norway spruce (Picea abies)-domi nated forests on fertile, drained peatlands located along a north-south gra dient in Sweden. Naturally established seedlings of mainly spruce and pubes cent birch were inventoried with respect to numbers and height, and planted (large, bare-root) spruce seedlings in 10-year-old shelterwoods and clearc uts with respect to survival, damage and height development. Two shelterwoo d densities were studied, 140 and 200 trees ha(-1). The planting treatment also included site preparation (mounding in shelterwoods, mounding and no m ounding in clearcuts). The planted seedlings and the natural regeneration w ere inventoried 9 and 11 growing seasons after cut, respectively. Large numbers of naturally established spruce and birch (Betula sp.) seedli ngs were obtained without soil preparation in the shelterwoods. The height development of these spruce seedlings was, however, much slower than that o f the planted shelterwood seedlings, indicating 2-3 times longer regenerati on period (up to 20 years) for the natural regeneration alternative. In the clearcuts, only birch seedlings established naturally. In all the study ar eas, planting in mounds was equally or more successful (survival, height, d amage) in shelterwoods than in clearcuts. Planting without mounding in the clearcuts was nor successful (low survival rate and height, extensive damag e). In general, the number of naturally established seedlings in shelterwoo ds, and the survival rate of planted seedlings in clearcuts and shelterwood s, were much lower in the study areas in central Sweden than in the areas i n the north and south. The results from the study suggest that shelterwood methods (by natural establishment or planting) used in highly productive sp ruce forests yield acceptable or desirable levels of regeneration. (C) 2000 Elsevier Science B.V. All rights reserved.