Permafrost

Cryospheric changes in the West Siberia northern taiga
Moskalenko Nataliya
(Earth Cryosphere Institute SB RAS, Vavilov Street 30/ 6, Moscow, 119991, Russia,
nat-moskalenko@yandex.ru)
Abstract: The monitoring of landscape and permafrost conditions in natural ecosystems and on
sites disturbed by a lining of linear structures will be carried out since 1971 till the present time
in northern taiga of West Siberia. The observations over a soil-vegetation cover, thickness and
moisture of an active layer, soil and ground temperature, engineering geological processes are
carried out on constant profiles and plots. Repeated (with an interval 3 years) landscape
mapping of a gas pipeline route and the adjacent not disturbed territory and repeated leveling
of a constant profile surface, have allowed to lead inventory of ethnogeny disturbances and
forms of engineering geological process displays.
Carried out monitoring observations have revealed the changes of landscape and
permafrost conditions caused by climatic changes and influence of the anthropogenic factor. Air
temperature steadily rose from a beginning 70 years. For example, trend of increase of mean
annual air temperature has made on the data of Nadym weather station for 1972-2004 years
0,03 0 С per one year. The increase of air temperature has caused increase of frequency both
covering by shrubs and occurrence of wood plants in tundra ecosystems. The steady increase of
seasonal thaw depth in all natural complexes, behind exception flat peat land, also is connected
to increase of air temperature in the summer period. The increase of variation amplitude of the
maximal seasonal thaw depth on years is appreciable expressed for last 10-15 years.
The removal of a vegetation cover on a gas pipeline route has resulted in increase of an
active layer thickness in all investigated ecosystems. However size and character of these
changes essentially differ in time in different landscape conditions. So for example, on frost
mounds, composed with a surface by sands underlain by ice-rich silty and clayey deposits, the
active layer thickness has increased in 2 times per the first years after disturbance (from 110 up
to 230cm). The next years the increase of seasonal thaw depth was small (10 % from average
size of the maximal active layer thickness. Last decade the increase of the maximal active layer
thickness as in disturbed (up to 370сm), and in natural conditions (up to 180сm), caused by
increase of air temperature was marked.
On the contrary, on flat peat land per first five years after removal of a vegetation cover the
seasonal thaw depth has increased slightly (with 57сm up to 64сm, i.e. by 13 % from initial
size). However further in connection with a surface subsidence of the disturbed plot and
development of water pools the appreciable increase of seasonal thaw depth up to 120сm in 11
years after disturbance was marked. Through 18 years the maximal active layer thickness
becoming 190сm has exceeded initial size in 3 times. Stabilization of the maximal active layer
thickness is not observed on disturbed peat land for the investigated 33-year's period.
The observable increase of ground temperature in various landscape conditions also is
caused by increase of air temperature. The maximal changes of ground temperature are marked
on big palsa peat land. The ground temperatures at the depth of a layer with annual temperature
fluctuations (10m) on these peat lands for the period of research have increased from -1,8 0 up to
-0,5 0 С. Trend of ground temperature increase has made 0,03 0 С per one year.
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