Influence of land relief and soil properties on stand structure of overgrown oak forests of coppice origin with Sorbus torminalis

Traditional forest management as coppicing and coppicing-with-standard are recently considered as beneficial for biodiversity in woodlands. Cessation of coppicing leads to changes in stand structure and often loss of biodiversity. In contemporary Polish forestry coppicing is not applied, however some stands of coppice origin persist in Silesia until present. The overgrown coppice oak forests that cover the southern slopes at the foothills of the Sudetes Mountains (Silesia, Central Europe) are considered to be Euro-Siberian steppic woods with a Quercus sp. habitat (91I0): a priority habitat in the European Union, according to the Natura 2000 system. They support one of the largest populations of wild service tree (Sorbus torminalis Crantz) in Poland. In this study we investigated the relation of stand structure and trees parameters with environmental variables. The results showed considerable variability of stand volume, tree density and stems’ size correlated mostly with soil texture, but not nutrient content. We attributed it to soil dryness which seems to be the crucial factor controlling growth of trees. The natural regeneration of trees concentrated mostly on non-exposed sites on less acidic soils, but seedlings of wild service tree were present almost exclusively on most insolated sites, with shallow acidic soils. However, the regeneration of trees in sapling stage was restrained by browsing. Results suggest that maintaining of Sorbus torminalis requires protection against browsing, and some kind of active management is necessary to retain the observed stand structure with high proportion of wild service trees in stands on more fertile soils.