The aim of research is to estimate forest state within the Great Vasuygan mire marginal part using satellite and field data. Specifically, the objective of this study were to: 1) conduct field landscape studies and assessment of paludification intense to create training samples and asses the accuracy of satellite images interpretation; 2) distinguish paludification landscapes in mix forest surroundings raised bog massif by a semiautomatic landscape classification method and assessment mire influence zone; 3) create the classification of the raised bog massif spatial structure. The average length of mire influence zone is 3.9 km with fluctuations in the range of 0.6-8.4 km. Spatial structure is indicator of the development stage and the slope of the raised bog and, as a consequence, the intensity of surface runoff from mire into the surrounding areas. The length of mire influence zone differs between the selected classes of spatial structures and is mainly determined by the distribution of complex microlandscapes, the presence of which reflects the final stage of raised bog massif development.
classification method and assessment mire influence zone; 3) create the classification of the raised bog massif spatial structure. 2
The objects of study are the North-Eastern spurs of the Great Vasyugan Mire – Iksa and Bakchar raised bog
massif (figure 1). The study area is located in the southeast West Siberian plain within Middle Ob River watershed.
The territory belongs biogeographically to the south taiga zone. The fluviolacustrine loams and clays represent a
quaternary deposit. The quaternary deposits thickness on the interfluve of the Bakchar River and the Iksa River
reaches 40-60 m [
The GPR surveys, which covered a total distance of 2.3 kilometers, were conducted in March 2017 and 2018. We employed a GPR system “OKO-2” (“Logical systems”, Russia) with 250 MHz shielded antenna and displacement sensor. We placed marks as vertical lines on radiograms every 50-100 m during the GPR surveys to collect peat core and to binding high-altitude data in summer. The step size between the marks was determined by the peat deposits heterogeneity. The marks, the beginning and end of the GPR transect were located with GPS (accuracy: 5 m).
In accordance with the marks on the GPR profile in the summer of 2018 made contact sensing of peat deposits on
33 points, including definition of peat deposits depth, the allocation of stratigraphic layers by the types and degree of
peat decomposition by the visual method [
The paludification zone definition was conducted on the basis of Landsat 8 data classification using SemiAutomatic classification plugin. The training sample was compiled using the data of field landscape studies and included 4 classes of sites indicating the development of paludification processes within forest: 1) swamp forest areas characterized by mass felling of trees; 2) pine-shrub grass-sphagnum bogs outside the raised bog massif main contour, 3) cedar-birch swamp forest; 4) pine-birch swamp forest. Assessment of the mire influence zone length is determined by the method of landscape profiling. We laid 40 profiles crossing the border of raised bog massifs parallel to the drain lines. We measured. the bog massif length, the distance from the watershed to the marginal part of the mire, the extent of the mire influence zone, the surface slope within the influence zone, a set and the length of the main microlandscapes (hummock-hollow and hummock-pool complexes, pine-dwarf shrubs-sphagnum bogs, grass-moss mires). The length of mire influence zone was measured in accordance with the distribution of plots allocated by the results of Landsat image interpretation on each profile. The surface slope map is drawed by the method of raster interpolation Topo to Raster based on the elevation of topographic maps with correction on the lines of the hydrographic network.
We used the method of cluster analysis to classify spatial structures of raised bog massifs. The comparison of values paludification zone length differences between the classes was conducted using tests of Mann-Whitney and Kruskal-Wallis. The dependence of the paludification zone length, the characteristics of the spatial structure and the surface slope was determined using the principal components method. 3 3.1
Swamp forests with a predominance of Betula pubescens are widespread within the key area. Subdominants of the
tree layer are Pinus sibirica, Pinus sylvestris, Picea obovata, Populus tremula. The tree layer height varies from 15 to
22 m with a cover of 20-60 %. Typical representatives of the shrub layer are Ribes nigrum, Rosa acicularis, Sorbus
sibirica, Rubus idaeus. The layer projective cover usually does not exceed 5-10 %. Various species of sedges (Carex
acuta, C. Elongata, etc.), horsetails (Equisetum palustre, E. Sylvaticum, etc.), reed grasses (Calamagrostis canescens,
C. neglecta, etc.), ferns (Gymnocarpium dryopteris, Athyrium filix-femina, etc.) are widely distributed in the grass
layer. Bryidae occupying a fallen rotten trunks and tree trunks hummock dominate in the moss layer often [
Shallow peat soils with a peat layer depth 0,7–1 m and peat-gley soil with a peat layer less 0,7 dominate within the mire influence zone. The peat deposits depth within the key area reaches 1.75 m, the average value is 0.4 m. Sapric wood and wood-grass peat with a high degree of decomposition dominate in the stratigraphy of swamp forest peat deposits. 3.2
Spatial structure of large raised bog massif within the Great Vasyugan Mire spruces is characterized by a change of plant communities in the following sequence: 1) pine grass-sphagnum bogs, stretching a narrow strip along the mire border, 2) the pine-shrub-sphagnum bog, occupying a large area within the raised bog massifs slopes, 3) ridgehollows and ridge-pool complex pine-shrub grass-sphagnum bogs in the central part of the raised bog massifs. The large raised bog massif northern parts and smaller raised bog massif are characterized by a lack of complex bogs and a simpler spatial structure. The averages width of the raised bog massifs in parallel to the direction of flow is around 11 km, in some areas up to 24 km. The surface slope within the mires ranges 0-0,2°, but for the most part it does not exceed 0.05°. The surface slope does not exceed 0.3° and an average of about 0.1° within the watershed plains occupied by forests and swamp forest (figure 2).
According to principle component analysis the mire influence zone length is largely determined by the raised bog massif width (0.92), a length of ridge-hollow (0,64) and ridge-pool (0,63) complex bog. The surface slope of the areas adjacent to the mire have less influence (0.30) due to the low variation of the values with almost flat relief within the area under study (figure 3).
The raised bog massif spatial structures are combined to four classes as a result cluster analysis of bog microlandscapes length data array.
The first class of spatial structures is characterized by a wide spread of complex bogs, including ridge-pool microlandscapes. The length of ridge-pool microlandscapes reaches its maximum value within the considered area of 15 km, with an average value of 8.7 km (figure 4, 6). Unlike the first, the second class is characterized by a large distribution of ridge-hollow complex, with absence ridge-pool complex. The raised bog massif marginal parts are occupied by wood and wood moss microlandscapes. The mire influence zone length values are maximum in the first and second spatial structures class within the key area. The length reach to 8.4 km from the border of the raised bog massif with an average value of 4.6 km.
The third spatial structure class is characterized by a wide distribution of the grass-moss microlandscapes. The average length of ridge-hollow complex does not exceed 1 km, ridge-pool complexes are absent in most cases. The average length of the mire influence zone is 3.5 km. The fourth spatial structures class is characterized by a lack of a complex and wide distribution of wood and wood moss micro-landscapes. The values of mire influence zone are minimum length in the fourth class within the site under study which average made 1,7 km (figure 5,6). Thus, the study result is assessment of the mire influence zone and forest state within the marginal part of the Great Vasyugan Mire North-Eastern spurs. The average zone length is 3.9 km with fluctuations in the range of 0.6– 8.4 km. The dependence of the mire influence zone length from the characteristics of the spatial structure is statistically confirmed. Spatial structure is indicator of the development stage and the slope of the raised bog surface and, as a consequence, the intensity of surface runoff from mire into the surrounding areas. The length of mire influence zone differs between the selected classes of spatial structures and is mainly determined by the distribution of complex microlandscapes, the presence of which reflects the final stage of development of the raised bog massif. 4
The use of modern research methods based on the analysis of satellite data and GIS mapping allowed to obtain qualitatively new scientific data on the spatial differentiation of adjacent areas to the mires and to assess the length of the influence zone of large raised bog massif. The developed algorithms for modeling the hydromorphic transformation of ecosystems will be universal for the taiga zone of Western Siberia and can be used to assess the paludification processes in large areas. This study was funded by RFBR, research project no. 18-35-00387.