Peculiarities of tree-ring series in larch affected by the ground fire of 1908

Nowadays a special attention is paid to the estimation of all sources of the CO 2  released into the atmo-
sphere. It is well – known that heavy forest fires are one of the sources of the atmosphere pollution. 
However, ground fires also make their contribution to the problem. If the volume of the CO 2  emission 
caused by the fires in Russia is, on the average, 230 mln tons a year, then 41% of it is due to the ground fires [1]. 
The method of the analysis of the residual gases in the tree discs developed by the authors has allowed making 
a number of conclusions on the effect of the ground fire in the region of the Podkamennaya Tunguska river in 
1908. It is known that in 1908 a space object exploded there, which resulted in the trees knocked down in an 
area of 2150 ±25km 2  followed by a ground fire that damaged the vegetation in an area exceeding 100km2[2]. 
The investigation was carried out based on the discs of the Gmelin larch (Larix gmelinit (Rupr.) Kuzen.) pre-
sented by the participants of the Complex independent expedition (CIE Novosibirsk, Tomsk) V.D. Yashkov (U) 
and I.K. Doroshin (D). The analysis of the residual gases vacuum – desorbed from the wood of the disc rings 
was performed using a photoacoustic spectrometer with a tunable CO 2  laser. A special procedure was used to 
investigate very thin rings [3]. The cyclic recurrence in the obtained results was revealed by means of the high 
– resolution spectral and cross - spectral analyses based on the maximum entropy method. It was found that the 
event of 1908 in the region of the Podkamennaya Tunguska river had induced the CO 2  (and H 2 O) accumulation 
retained for 30 years in the stem wood in most of the trees that survived the catastrophe (Fig. 1). It is highlyprobable that the excess CO 2  content could diffuse from the stems into the atmosphere. The analysis of the be -
havior of the CO 2  chronologies and the ring width has shown the 1908 catastrophe to cause a change of the 4 – 
year cyclicity in the chronologies for a 3 – year one in the post – catastrophe period. This work increases the list 
of the experimental materials on the above region and can be of interest for specialists dealing with the atmo-
sphere – biosphere exchange in ecologically unfriendly regions.