Earth`s Cryosphere, 2018, Vol. XXII, № 4, p. 12-19

THE TEMPERATURE REGIME OF SOILS IN NORTHERN YAKUTIA

D.G. Fedorov-Davydov1, S.P. Davydov2, A.I. Davydova2, V.E. Ostroumov1, A.L. Kholodov1, V.A. Sorokovikov1, D.G. Shmelev1

1 Institute of Physicochemical and Biological Problems in Soil Science, RAS, 2, Institutskaya str., Pushchino, Moscow region, 142290, Russia; muss-96@yandex.ru
2 North-Eastern Science Station, Pacific Ocean Geography Institute, FEB RAS, P/O box 18, Cherskiy Community, Nizhnekolymskiy Region, Yakutia, 678830, Russia; davydoffs@mail.ru

Soil profiles in Northern Yakutia differ in average duration of the season of positive temperatures, the difference being 2.3 times between soil types and 1.8 between zonal loam soils, at a depth of 20 cm. The seasons of >0 °C and >5 °C soil temperatures may be shorter in wetter boggy areas with thicker organic horizons. The durations of fall freezing and persistent near-zero temperatures vary from 1–2 months for tundra cryozem and gleyzem (turbic glacic cryosols) to 2.5–3.5 months for taiga cryometamorphic soils (cambic turbic cryosols), organic cryozem (folic cryosol), and tundra podburs (spodic turbic cryosols). The active layer freezes mostly from above (top to base), except some years of cool summers in the tundra zone when it freezes partly from below. The tundra and taiga soils show a warming trend of the soil climate since the late 1990s dynamics according to annual freezing degree-day sums. The soils of Northern Yakutia vary in total heat spent on active layer thawing Qt > 0, the difference reaching 10 times.

Soil temperature regime, soil climate change, active layer, freezing of active layer from above and from below, near-zero temperatures, zero curtain, Northern Yakutia

DOI: 10.21782/EC2541-9994-2018-4(12-19)