Spatial diversity of forest regeneration after catastrophic wind in northeastern Poland

Abstract

Abstract: We examined the spatial diversity of young growth established after the catastrophic windthrow occurred in 2002 in the northeastern part of Poland. Our observations and measurements were conducted on permanent circular measurement plots located in the Szast Protected Forest (continental lowland temperate forests) that were established 3 years after the windstorm and left to natural succession. We evaluated the spatial indices characterizing the four main aspects of stand structure: the spatial arrangement of seedlings and saplings, species mingling, tree size diversity at the local spatial scale and the overall structural complexity index. The calculations were conducted in parts of the forest with differing severity of disturbance. The obtained results indicated the prevalence of a random arrangement of young growth. Clumps of regeneration were observed to a lesser degree in all parts of the forest. The species diversity was moderate and was the highest in the slightly or severely disturbed stands. Scots pine formed homogenous groups of regeneration and oaks were intermingled among other tree species. The height of the natural regeneration was moderately or highly differentiated in all stands. The overall structural diversity index showed that stand regeneration in the slightly or moderately disturbed stands was more differentiated than the young growth in the severely disturbed stands. The size differentiation of young growth is a long-lasting process and thus should be considered in practices aimed at the re-growing of areas after a natural disturbance. This process might be used to the replace monocultures with more diversified forests even in poor forest site types.