Gley-Podzolic soils (profile Ao-A2hg-Bf-B1-BC-C) of spruce forests of the northern taiga within the Komi Republic are viewed. Climate is rather severe with a mean annual air temperature of -2.3 degr.C, mean annual precipitation of 525 mm, snow cover remaining about 220 days, and snow depth in a forest averaging 40 to 50 cm. According to the temperature regime, Gley-Podzolic soils belong to the group of cold soils with the extended period of seasonal freezing. They are kept in frozen state for 7 to 7.5 months. During this period, temperature at the soil surface is -2 degr.C, freezing depth varies from year to year from 0.6 to 1.2 m. In the lower part of the frozen layer temperature never drops below -1 degr.C. Temperature is rather constant below frozen layer being equal about 1 degr.C. The soil thaws out by May, 10 to 15. Temperature of +5 degr.C spreads deep into the soil at the rate of about 1 m per 1.5 months. Such a slow warming up results from the heat insulated role of the litter (Ao), the latter being 5 to 7 cm thick. The Ao temperature regime differs sharply from that of mineral horizons. The onset of optimum temperatures (15 degr.C and higher) in the litter is observed in the second decade of June, whereas in the podzolic (A2) horizon temperature achieves this level at the end of June and keeps during 10 to 15 days. Warming up of the Bf and B1 horizons is performed with a large delay and is rather short-termed. Root layer is only 0.2 m thick and is warmed up in average up to 7 to 9 degr.C. In the BC and C horizons occuring at the depth of 1.0 to 1.5 m, temperature reaches 5 degr.C in the middle of August. At the first decade of September the heat loss starts. Temperature is rather constant at this depth being equal 2 to 4 degr.C.

The low heat resourses prevent penetration of arboreal plant roots into soil. There is no evidence of cryoturbation in the soils. Period of the active soil forming process (temperature of 5 degr.C and higher) totals 2.5 to 3.0 month. It determines relatively low biological productivity of the Gley-Podzolic soils.

Dr. IYA V. ZABOEVA
Chief Researcher,
Department of Soil Science,
Institute of Biology,
Komi Scientific Center,
Ural Branch,
Russian Academy of Sciences.
RUSSIA 167610 Syktyvkar,
ul.Kommunisticheskaya, 28
Phone: (8212) 425240
Fax: (8212) 420163
E-mail: biol@omkomi.intec.ru