MICROSCALE VARIABILITY OF ACTIVE LAYER PROPERTIES OF TAIGA AND SUBARCTIC TUNDRA OF EASTERN SIBERIA
Georgiadi, Alexander (1), Onishchenko Vladimir (2)
(1) Institute of Geography, Russian Academy of Sciences
(2) Institute of Agrophysics , Russian Agricultural Academy
Special plots were organized for investigation of microscale variability of main water- and thermophysical soil-ground properties within seasonal melting (active) layer at area covered by larch forest in Spasskaya Pad' (in vicinity of Yakutsk) and in tundra area (in vicinity of Tiksi). Plots included 16 and 23 vertical soil profiles accordingly having square form.
It was taken more than 300 samples from main genetic soil horizons and it was measured their thickness as well as depth of permafrost table. These samples were used for determination of following soil properties: density, specific surface, moisture at wilting point, field capacity, relation between water tension and moisture content, coefficient of filtration, relation between water conductivity and moisture content, coefficient of thermal conductivity and others.
Soil properties are characterized by high variability within small area. Coefficient of variation of soil properties in upper layer is near to 1 decreasing along the profile. Depth of permafrost table is varied in limits 110-150 cm (in taiga site) and 25-30 cm (in tundra).
Profile of cryogenic taiga podzolised sandy loam soils is characterized by big differences of soil properties of upper layer and lower one. Leaf litter (Ao) with thickness up to 10 cm which consists of dark-gray, friable, with poorly decomposed leafs of larch, birch, aspen, cowberries, a lot of small roots and horizon A1 (dark humus layer with similar thickness) which is strongly decomposed and it includes a lot of small roots are characterized by the highest values of most of soil properties (thermal conductivity has the lowest value in mentioned horizons). Vertical profile of the some of properties (specific surface, soil moisture content at wilting point, field capacity, relation between water tension and soil moisture content) is characterized by so called C-type distribution. According to this type the highest values are observed in upper soil layer decreasing very quickly along soil profile. Values of soil properties have not big differences from each other in middle part of profile. Values are increased a little bit near to permafrost table.
Profile of swamped cryogenic tundra soil is characterized by considerable differences between upper (At) and lower (A1) horizons. Values of physical properties of two main horizons (At-peated dark brown, saturated by water with vegetation remainders including decomposed ones and roots and A1-dark gray, wet, havey loamy, with small gravel, saturated by water) are differed from each other in 5-10 times.
Features of vertical and spatial distribution of physical properties are analyzed.
Submittal Information
Name :
Date :
Dr. Georgiadi, Alexander
30-May-01-12:19:58
Organization :
Theme :
Institute of Geography, Russian Academy of Sciences
