Long-Term Postfire Changes of Soil Characteristics in Dark Coniferous Forests of the European North

Resumo

Changes in characteristics of the upper soil horizons in dark coniferous forests in the course of their postfire restoration were assessed. The studies were carried out in the northern taiga forests exposed to fire 8 to 400 years ago in the Kola Peninsula and in the middle taiga forests burned 70 and more than 500 years ago in the northern Cis-Ural region (Pechoro-Ilychskii State Biospheric Reserve). Samples from 23 soil pits on 20 test plots were analyzed. The actual acidity, loss on ignition, contents of exchangeable K, Ca, and Mg and mobile Mn, Fe, and Zn were determined. Two boundaries (~80 and 160–200 years after fire) and three main periods in the postfire dynamics of the upper soil horizons properties were established. The ash and Fe content in the litter was found to decreases about 80 years after the fire. In 160–200 years after fire, the thickness of the forest litter is restored and stabilized at the level of about 9.7 (8.3–10.4) cm; the pH value and the Ca, K, and Mn concentrations in the litter become lower. Thus, it can be concluded that the properties of soils under dark coniferous forests of the European North considerably change in the course of postfire successions.