HR: 1340h
AN: C13B-0275    [Abstracts]
TI: Influence Of Clear-cutting On Thermal and hydrological Regime In The Active Layer Near Yakutsk, Eastern Siberia
AU: * Iwahana, G
EM: go@lowtem.hokudai.ac.jp
AF: Research Fellow of the Japan Society for the Promotion of Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 0600819 Japan, Sapporo, 0600819 Japan
AU: Kobayashi, Y
AF: National Institute for Agro-Environmental Sciences, Kannnonji Tukuba, Japan, Tukuba, 305-8604 Japan
AU: Machimura, T
AF: Graduate School of Engineering, Osaka University, 1-1 Yamadaoka Suita, Osaka Japan, Osaka, 565-0871 Japan
AU: Fedorov, A N
AF: Permafrost Institute, Russian Academy of Science, Yakutsk, Russia, Yakutsk, 677018 Russian Federation
AU: Fukuda, M
AF: Institute of Low Temperature Science, Hokkaido University, N19 W8 Kita-ku, Sapporo, 0600819 Japan
AB: Thermal and hydrological conditions in the active layer were investigated simultaneously at a mature larch forest (control site) and a cutover, which experienced clear-cutting in November 2000 during the thawing periods from 2001 to 2003, near Yakutsk, Eastern Siberia. The two sites were located about 100m apart and the cutover was formerly a part of the control larch forest site. The aims were to clarify the characteristics of heat and water budget in the active layer, and to assess the influence of clear-cutting on permafrost and active layer conditions, based on field observations at both intact and clear-cut forest. Clear-cutting enhanced ground thawing and the difference in the active layer thickness between the forest and the cutover (1-year) was 14cm. The soil water content drastically decreased at the forest, while that at the cutover was retained in during the first thawing season after clear-cutting. Marked changes in the active layer conditions were limited only to the first thawing season. The difference in the maximum thaw depth did not expand significantly in the second thawing season despite the increased ground heat flux at the cutover site. Thermal and hydrological analyses of the active layer revealed that the storage of latent heat was a predominant component in the energy balance in the active layer. Thus, the soil moisture condition, especially spring ice content in the active layer, plays an important role in controlling the energy balance of the active layer. Further increases in the maximum thaw depth at the cutover site were inhibited by the thermal inertial effect of the larger amount of ice in the second spring after disturbance.
DE: 1800 HYDROLOGY
DE: 1803 Anthropogenic effects
DE: 1823 Frozen ground
DE: 1866 Soil moisture
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting