Fragm. Flor. Geobot. 45(1–2): 203–212, 2000 Distribution of Sorbus aucuparia (Rosaceae) regeneration in relation to trees in a subalpine spruce forest (W Carpathians, Poland) JAN HOLEKSA HOLEKSA, J. 2000. Distribution of Sorbus aucuparia (Rosaceae) regeneration in relation to trees in a subalpine spruce forest (W Carpathians, Poland). Fragmenta Floristica et Geobotanica 45(1–2): 203–212. Kraków. ISSN 0015–931x. ABSTRACT: The distribution of rowan (Sorbus aucuparia L.) saplings was analyzed within and around a large windthrow in a subalpine spruce forest of Babia Góra National Park. Rowan sap- ling density was higher under the spruce canopy than in the open. Young rowans accumulated under trees in the understory of the spruce stand around the windthrow, and their density de- creased with the distance from trunk bases. Seed dispersal by birds and spatial differentiation of ground vegetation are suggested as possible factors determining the distribution of rowan sap- lings. It is suggested that the rowan, a pioneer species, does not necessarily invade gaps in this subalpine forest but rather forms a bank of suppressed individuals in the understory, which are released after stand breakup. KEY WORDS: canopy gap, regeneration, spatial structure, Plagiothecio-Piceetum J. Holeksa, Department of Geobotany and Nature Conservation, Silesian University, Jagiellon ´ska 28, PL–40–032 Katowice * INTRODUCTION One of the most striking features of European subalpine spruce forests is the very simpli- fied structure of tree stands in the optimal phase of their development. Monolayered and dense spruce stands cover large areas, as the optimal phase lasts 100–200 years and is the longest one in the development cycle (Korpel’ 1980; Mayer & Ott 1991). These stands often undergo catastrophic destruction caused by strong wind, hailstorms, snow loads and insect outbreaks (Korpel’ 1982; Fisher 1992). Sorbus aucuparia L., a short-lived and light-demanding deciduous tree (Ellenberg 1986; Kräuchi & Kienast 1993), is one of the most important pioneer species which develops in gaps and large disturbed patches and launches the succession toward spruce stands (Korpel’ 1980; Vacek & Tesar 1991; Fischer et al. 1990; Fischer 1992; Loch 1994; Reif & Przybilla 1995; Kooijman et al. 2000). * Present address: W. Szafer Institute of Botany, Polish Academy of Sciences, Lubicz 46, PL–31–512 Kraków, Poland; e-mail: holeksa@ib-pan.krakow.pl