Specjacja fosforu w leśnych glebach rdzawych na obszarach popożarowych

The studies on contents and profile distribution of total phosphorus and its fractions extracted according to the procedure of Hedley et al. [1982] in a modification of O’Halloran et al. [1987] in forest Brunic Arenosols of post−fire areas in the Rudy Raciborskie Forest District (S Poland) were undertaken. Five soil profiles developed from fluvioglacial sandy deposits of the Oder Glaciation were described and sampled 21 years after the fire occurrence and analyzed using standard procedures. Total content of the element was among typical for Brunic Arenosols of Poland, ranging from 683.1 to 880.4 mg/kg in Ofh horizons, from 154.2 to 566.5 mg/kg in mineral horizons affected by soil−forming processes and from 115.5 to 384.2 mg/kg in parent material. The content of distinguished phosphorus fractions varied, reflecting the effect of environmental factors and brunification soil−forming process. Residual fraction predominated in parent material, organic in O and most of A−horizons and bounded to sesquioxides in B−horizons. The observed proportions between residual fraction and sum of the remaining fractions were typical for soils of old−glacial areas, reflecting considerable degree of mineral substrate weathering. An effect of fire was not clear due to the lack of a reference soil. However, the studied soils showed some specific features, that can be explained by the influence of fire. Low content of fraction bounded to calcium and apatites is the first and elevated concentration of fraction bounded to sesquioxides in parent material is the other one. Profile distribution patterns of mentioned above fractions suggest leaching of phosphorus labile forms and their stabilization in deeper parts of the studied soils. This process could be initialized or accelerated by fire. Finally, it can be concluded, that studied properties of the contemporary soils are stronger influenced by pine forest vegetation than by fire before 21 years.