Abstracts for the 5th International GAME Conf.

3-5 October 2001

Aichi Trade Center

Nagoya Japan

VARIABILITY OF ACTIVE LAYER THICKNESS, GAME-SIBERIA STUDY AREA, CENTRAL YAKUTIA

Vasiliev, Ivan (1), Gerasimov, Eremey (1)

During the last 4-5 years variability of the active layer thickness has been studied at experimental sites representing five terrain types of the Spasskaya Pad monitoring area: inter-alas, alas, sand-ridge, inter-ridge depression, and slope. Variability of the active layer thickness at a given site depends on variability of biohydrothermal conditions in a given year. In the majority of the terrain types, the active layer thickness attained highest values in 1997 with a moderately warm and moderately wet summer, and lowest values in 1996 with the lowest summer precipitation. In the hottest (1998) and the coolest (2000) summers with small amounts of precipitation, the depths of thawing were close to the long-term average. In the cut areas, the active layer thickness had consistently lowest values throughout the period of observation. Soil moisture content sharply increases in the first years after tree removal, because transpiration from trees is eliminated. Moreover, soil moisture in the landscapes resting on permafrost with abundant ice wedges is recharged not only by precipitation, but by thawing of ground ice. The active layer thickness has intermediate and more stable values on the old clearings with larch forest. Relative stability is attributed to the restoration of the soil moisture regime as new plant species developed. On the clearings, soil moisture content plays a significant role in variation of the thaw depth and rate, being strongly dependent on time since tree removal and succession stages. On the whole, interannual variation of the active layer thickness relative to the long-term average is: 15 to 20% in inter-alas, 5 to 15% in alas, 7 to 15% in sand-ridge, 10 to 30% in inter-ridge depression, and 30 to 40% in slope terrain types. For the disturbed sites, the variation is 2 to 14%.

Submittal Information

Name : Date :
    Vasiliev, Ivan
    30-May-01-18:34:22
Organization : Theme :
    Melnikov Permafrost Institute, Russian Academy of Sciences
    Theme 2
Address : Presentation :
    Yakutsk-10, Permafrost Institute
    Only poster
Country : Abstract ID :
    Russia
    T2VI30May01183422
Phone : Fax :
    4112-44-4887
    4112-44-4476
E-mail :
    fedorov@mpi.ysn.ru