Wpływ właściwości gleb piaszczystych na bonitację drzewostanów sosnowych w południowo-zachodniej Polsce. I. Odczyn, zawartość CaCO3 i cechy związane z głębokością gleby

The research was conducted in 268 Scots pine (Pinus sylvestris L.) stands, separately on soils of different moisture – non−gleyic (215 plots) and gleyic (53). The site index (B) of every Scots pine stand was determine as mean height of the ten thickest trees per 0.1 hectare, recalculated for the base−age of 100 years. The results show clearly negative relationship between the pine site index and pH values, that is probably caused by positive impact of soil acidity on (i) mycorrhiza symbiosis and (ii) nutrients releasing from minerals in weathering processes. The optimum soil pH for Scots pine site index was defined as regarding ca. 4.5 pHH2O and 4.0 pHKCl. There was not stated any impact of CaCO3 content in soil parent material on pine growth. The soil depth was positively related to the site index only when non−gleyic soils were concerned. On gleyic soils any relation between soil depth and pine growth was found. The results showed that in different soil moisture conditions, properties of opposite soil zones play the key role for the pine growth. When pine was planted on non−gleyic soils, the site index was much more related to properties of deeper horizons and parent material than of topsoil, while on gleyic soils the site index was correlated to properties of surface soil layer mainly.