Evaluation of the trophism of soils in the ‘Rybitew' strict protection area in the Kampinos National Park based on the soil trophic index

The aim of the study was to assess the trophism of soils in the strict nature protection area using the soil trophic index (SIG). The ‘Rybitew’ strict protection area (224.2 ha, created in 1965), is located in the north−eastern part of the Kampinos National Park (central Poland). The results of field and laboratory studies of the physicochemical and chemical properties of soils made it possible to determine their trophism by the SIG index. In the ‘Rybitew’ strict protection area, significant typological diversity of soils (10 subtypes) was found. The soils belong to the following trophic groups determined by the SIG: mixed coniferous forests (BM), mixed broadleaved forests (LM), alder forest (swamp broadleaved forest site) (Ol) and soil developed from low and transitional peatlands. The average value and range of SIG for particular trophic groups was: 19 (15−23) for BM, 26 (25−28) for LM, 34 for Ol was well as 23 for organic soil developed from low peatland and 21 for organic soil made from transitional peatland. Most of the ‘Rybitew’ area is covered by Podzols, Brunic Arenosols and Luvisol occurring in the trophic group of BM and LM. A lot of the soils undergo acidification process, which leads to a reduction in their trophism due to the excessive share of pine in the stand. This causes the podzolization process of Luvisols and significant acidification of the upper horizons, high C:N value and the moder type ectohumus formation, especially in Haplic Gleysols and Haplic Phaeozems. The large typological and trophic diversity of soils and the vegetation covering them in the ‘Rybitew’ strict protection area confirm the rightness of its creation