SPATIAL PATTERN OF A PIONEER TREE SEEDLING BANK IN OLD-GROWTH EUROPEAN SUBALPINE SPRUCE FOREST

摘要

The study concerns the spatial relationships between rowan seedlings and variability of field-layer vegetation, density of spruce stand and distribution of adult rowan trees. A network of 0.05 ha circular plots spaced 40x40 m was established in the central part of a large, 27 ha rectangular tract in a subalpine spruce forest in the massif of Babia G6ra (Polish West Carpathians). On each circular plot rowan seedlings were counted, thedbhof all spruces was measured, and Lhe percentage of area covered with field-layer species was assessed. All adult rowans were measured and mapped over 27 ha and then their distances to 0.05 ha plots were measured. The recruitment of rowan seedlings starts before the destruction of the spruce stand and a seedling bank is formed. After gap creation rowan regeneration is hampered. Exuberant growth of the field-layer plants, especially the fetaAthyrium distentifolium, seems to be the most important factor limiting rowan regeneration under sparse spruce canopy and in gaps. The regeneration is not enhanced under conspecific adults growing in old gaps. It is still limited by exuberant field-layer vegetation, mainly A. distentifolium, that exists under rowan trees. The size of seedling bank is related to the distance to fruiting trees. Beyond 60 m from the nearest fruiting tree the number of young rowans drops distinctly. The lack of abundant seedling bank at longer distances from mature trees suggests that the development of dense rowan thickets is possible only in gaps situated in the neighbourhood of fruiting individuals up to several dozen meters from them.