Development of vegetation in managed Scots pine ( Pinus sylvestris L.) stands in an oak–lime–hornbeam forest habitat

Abstract

A regeneration process of oak–lime–hornbeam community ( Tilio-Carpinetum typicum Tracz., 1962), developing after a clear cutting followed by a plantation of Scots pine stand ( Pinus sylvestris L.), is analysed. A study material comes from managed and strictly protected (The Białowieża National Park) part of the Białowieża forest. A series of managed Scots pine stands, comprising developmental phases from thicket to old-growth, is compared with an analogical series of managed pedunculate oak stands – Quercus robur L. (in case of managed stands considered to be in a harmony with a target tree species composition for a given site type), as well as with a series of natural (strictly protected since ca. 80 years) stands, occurring in the Białowieża National Park. The three experimental variants, occurring in similar site conditions, are compared with regard to the vegetation and stand structure, as well as to the chemical properties of two uppermost soil layers. Analysis of vegetation includes, i.a., calculation of a species richness, a share of species typical for Scots pine and oak–lime–hornbeam forest, ecological indicator values, as well as an analysis of overall floristic similarity by means of DCA ordination method. Soil conditions are studied by analysis of, i.a. pH in KCl and base saturation. It is concluded that the development of Scots pine stands on the site of oak–lime–hornbeam community, under conditions of the Białowieża forest, has not brought about neither a persistent site degradation nor degeneration of the community. Some differences between pine and oak managed stands occurring on the site of oak–lime–hornbeam forest in the vegetation and chemical properties of the topsoil are generally confined to the comparatively short time period; from thicket to high polewood stages. The acidifying influence of pine needle litter on the site and ground layer vegetation is balanced, or even overridden, by processes associated with the regeneration of the phytocoenosis, first of all by the influence (shading and litter fall) of a rapidly developing hornbeam ( Carpinus betulus L.) layer. Intensive regeneration processes of natural oak–lime–hornbeam community, supported by site eutrophication, caused by the input of air-borne chemicals and climate warming, lead to the growing discrepancy between Scots pine stands and site conditions. The results obtained suggest that the restoration of more natural conditions in the replacement Scots pine stands can be achieved, in a greater extent than previously assumed, by a means of spontaneous regeneration processes.