Landscape analysis of fire resistance and fire frequency index of forest geosystems in the south of the Selenga middle mountains
A.A. FROLOV, D.A. BYSTROVA
V.B. Sochava Institute of Geography, Siberian Branch, Russian Academy of Sciences, Irkutsk, Russia
Keywords: landscape map, components of geosystems, moisture exchange potential, satellite images, complex indicator, land surface temperatures
Abstract
We present the principles of landscape analysis of a territory and demonstrate the experience of implementing these principles on a step-by-step basis (functional, complex, dynamic, classification-hierarchical, and discrete) was demonstrated for assessing the fire resistance of forest geosystems in the south of the Selenga middle mountains. The practical expression of the step-by-step implementation of these principles involves analyzing the landscape-forming factors and conditions, selecting complex indicators of the functioning of geosystems, creating a landscape-information basis for assessment, and carrying out a correlated analysis of the resulting complex indicators and the landscape-typological map, followed by an assessment of fire resistance of different types of forest geosystems. Within the framework of this research program, intra-landscape conditions and features of forest geosystems (relief, nature of underlying rocks and soils, and vegetation) were analyzed, determining their fire resistance, and a landscape-information basis (landscape-typological map) of forest geosystems was built. The value of the near-surface temperature that characterizes the level of moisture exchange between the components of geosystems, which determines the micro- and mesoclimatic features of landscapes, is used as a complex indicator. To determine the moisture exchange potential, a correlative analysis of index images characterizing land surface temperatures (LST) and moisture (normalized difference moisture index, NDMI) was carried out, which were calculated on the basis of infrared channels of Landsat 8 OLI and TIRS satellite images. Forest geosystems with high fire resistance are characterized by a higher level of moisture exchange and by minimum values of LST. Further, a correlative analysis of results obtained by the data overlay method was carried out: a grid of landscape map selections was superimposed on the LST and NDMI index images to identify modal values of the land surface temperature characteristic of each type of geosystems. It was found that the minimum level of fire resistance is characteristic of pine forests of steppizated, sometimes dead-cover, forests on plains and foothill elevations, composed of aeolian and deluvial-proluvial deposits on soils of light mechanical composition. The reliability of the results from assessing the fire resistance of geosystems is confirmed by the analysis of the actual fire frequency index of forests conducted on the basis of a time series of Landsat satellite images over the past 50 years when fires affected approximately 51 % of the area of all forests of the study area.
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