Theme: East-West Interdisciplinary Boreal Forest Fire Experiment, Part 3 Moderator: A. Granström and G. Ivanova 8.8.1995 16:30 Room: U16
Ecology of the Forests of the Sym Plain, Krasnoyarsk Territory, Siberia
Furyaev, Valentin V., Ivanova, Gallina A., Angelstam, Per
The Sym plain is an area of low relief, with sandy surface materials of glacial outwash and alluvial origin. Very deep loose deposits are present, and there are numerous lakes and oligotrophic and mesotrophic bogs. Forests are dominated by pure pine stands of the Pinus sylvestrisLedumVaccinium vitis-idaeaPleurozium schreberi, P. sylvestris P. schreberiCladonia sylvatica (40 %), and Pinus sylvestrisPolytrichum commune dwarf shrub Sphagnum (20 %) forest types. Oligotrophic bog ridges with pools covered by P. sylvestrisdwarf shrubSphagnum forest cover 40 % of the landscape. The forest on the experimental fire site is a typical middle taiga pine forest of the Sym plain.
Because Atlantic air masses are transformed to continental over the Western Siberian Lowland, zones and subzones are clearly discernible across the landscape. The climate is cool and moist. Average annual air temperature ranges from 3.2 to 5.7°C. Total annual precipitation is 450500 mm, with wide year-to-year variations. Although most precipitation occurs in the summer, frequent dry periods are caused by dry cyclonic air masses coming from the south. In the past century, 26 droughts have occurred in the area (an average of 23 times per decade).
Fire season lasts from May to September, with most fires in June-July. The area burned is typically high. For Pinus sylvestrislichen forest types, fire periodicity varies from 4050 years in the north to 2529 years in the central part of Krasnoyarsk Territory. For the P. sylvestrisV. vitis-idaeaSphagnum forest type characteristic of the central part of the area, forest fire periodicity is 10 to 80 years. As in the rest of Siberia, periodic extreme fire seasons are common in the area. These seasons are remarkable for long rainless periods (up to 38 days), with relative humidities down to 30 %, and air temperatures up to 3035°C. Until the end of the 19th century, extreme fire seasons in the central Krasnoyarsk Territory occurred from 34 to 7 times a century. This has increased to 2025 events in the 20th century. Most of these fires are human caused, as a result of intense forest exploitation in the area. For the past 50 years, extreme fire seasons associated with mass forest fires have occurred at least twice a decade, sometimes two years in succession.
Key words: landscape, forest, fire season, extreme fire season.
Correspondence: Valentin V. Furyaev, Institute of Forest, Russian Academy of Sciences, Siberian Branch, Forest Fire Laboratory, Akademgorodok, RUS-Krasnoyarsk 660036