G. A. Ivanova

DETERMINING EFFECTS OF AREA BURNED AND FIRE SEVERITY ON CARBON CYCLING AND EMISSIONS IN SIBERIA

The Russian boreal forest contains about 25% of the global terrestrial biomass, and even a higher percentage of the carbon stored in litter and soils. Fire burns large areas annually, much of it in low-severity surface fires – but data on fire area and impacts or extent of varying fire severity are poor. Changes in land use, cover, and disturbance patterns such as those predicted by global climate change models, have the potential to greatly alter current fire regimes in boreal forests and to significantly impact global carbon budgets. The extent and global importance of fires in the boreal zone have often been greatly underestimated. For the 1998 fire season we estimate from remote sensing data that about 13.3 million ha burned in Siberia. This is about 5 times higher than estimates from the Russian Aerial Forest Protection Service (Avialesookhrana) for the same period. We estimate that fires in the Russian boreal forest in 1998 constituted some 14–20% of average annual global carbon emissions from forest fires. Average annual emissions from boreal zone forests may be equivalent to 23–39% of regional fossil fuel emissions in Canada and Russia, respectively. But the lack of accurate data and models introduces large potential errors into these estimates. Improved monitoring and understanding of the landscape extent and severity of fires and effects of fire on carbon storage, air chemistry, vegetation dynamics and structure, and forest health and productivity are essential to provide inputs into global and regional models of carbon cycling and atmospheric chemistry.

Multielement composition of the aerosols of the forest fires of boreal forests upon burning of forest combustibles

Abstract The results of the SRXFA determination of the multielement composition of aerosols forming on fires in the boreal forests of Siberia are given. A comparison of the multielement composition of aerosols in the convective column of large forest fires and smoke plumes of surface fires with that of atmospheric aerosols of the Siberian region shows that the mass concentration of all analyzed elements exceeds the background values upon fires. A substantial change is observed in the quantitative composition of the aerosols.

Succession of vegetation after a high-intensity fire in a pine forest with lichens

This paper presents the results of 20-year studies into the impact made by an experimental high-intensity fire on ecosystem components and postfire succession in a middle-taiga pine forest. About 44% of forest fuel loads burned down during the fire, and the emission of carbon was more than 18 t C/ha. As a result of the fire impact, trees died within 3 years after the fire, and this resulted in a significant accumulation of fuel loads. Twenty years after the fire, the biomass of forest fuel loads surpassed the prefire values 4 times, which led to the possibility of the origin of a repeated high-intensity fire. The initial stage of postfire succession in the pine forest is determined by forest vegetation conditions and takes place with the replacement of dominant grass and shrubs. The agrochemical and hydrothermal soil indicators were revealed to be changed after the fire, and this promoted improved conditions for the origin and development of natural regeneration sufficient for the formation of forest stand.

Holographic method of nanoparticles diagnostics in liquid

The theoretical analysis of the dynamic holograms efficiency in the dispersion liquid medium is carried out. The mechanism of optical nonlinearity of the medium is due to the forces operating on the particles of the dispersed phase in light field. The summary nonlinear response of the nanosuspension includes two concentration mechanisms (electrostrictive and thermo-diffusive) and two thermal ones (light absorbing and particles drift caused by light pressure). The results are relevant for dynamic holography in the nanosuspensions, as well as for optical diagnostics of such media and thermo-optics spectrometry.

A study of thermal diffusion in a two-component liquid by z-scan method

In two-component fluid (binary mixture) the heat flow can cause concentration stream arising from occurrence of thermodiffusion phenomenon (Soret effect). As a result these phenomenon changes the magnitude of the transport coefficients of the mixture. In this paper the theoretical analysis of the light-induced thermodiffusion mass transfer in two-components liquid in a field of Gaussian beam was carried out. It was calculated a concentration contribution to the thermal lens response in the z-scan method.

Thermal mechanism of the radiation self-action in transparent nanogeterogeneous medium

A light induced drift of nanoparticles in a transparent viscous medium was discussed. The heating of the transparent dispersive medium under the influence of forces of light pressure and Dufour effect in a Gaussian light field was analyzed.