Two sphagnum peat monoliths from the same Tunguska bog (the first collected in 1999, the second one in 2002) have been studied. The peat samples were analysed by means of Particle Induced X-ray Emission technique. A precise dating was performed using excess Pb-210 geochronology and pollen/charcoal counting. The 1908 level has been located at the same depth, where palinological analysis shows a peak in the total pollen and Sphagnum spore counts. Abrupt collapses of tree pollen counting are connected with forest fires leading to subsequent forest declines (see figure, article, 1.15 Mb and abstract, 6 kb).