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

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This study was focussed on regeneration of Norway spruce ( Picea abies)-dominated forests on fertile, drained peatlands located along a north–south gradient in Sweden. Naturally established seedlings of mainly spruce and pubescent birch were inventoried with respect to numbers and height, and planted (large, bare-root) spruce seedlings in 10-year-old shelterwoods and clearcuts with respect to survival, damage and height development. Two shelterwood densities were studied, 140 and 200 trees ha −1. The planting treatment also included site preparation (mounding in shelterwoods, mounding and no mounding in clearcuts). The planted seedlings and the natural regeneration were inventoried 9 and 11 growing seasons after cut, respectively. Large numbers of naturally established spruce and birch ( Betula sp.) seedlings were obtained without soil preparation in the shelterwoods. The height development of these spruce seedlings was, however, much slower than that of the planted shelterwood seedlings, indicating 2–3 times longer regeneration period (up to 20 years) for the natural regeneration alternative. In the clearcuts, only birch seedlings established naturally. In all the study areas, planting in mounds was equally or more successful (survival, height, damage) in shelterwoods than in clearcuts. Planting without mounding in the clearcuts was not successful (low survival rate and height, extensive damage). In general, the number of naturally established seedlings in shelterwoods, and the survival rate of planted seedlings in clearcuts and shelterwoods, were much lower in the study areas in central Sweden than in the areas in the north and south. The results from the study suggest that shelterwood methods (by natural establishment or planting) used in highly productive spruce forests yield acceptable or desirable levels of regeneration.