Joint Study on Northern Environmental Change and Forecast

点击翻译按钮获取中文摘要

1) Boreal Forest Fire Impact to Hydrological Condition in PermafrostIn 1999 July 8^<th>, prescribed forest fire experiment was conducted at Poker Creek Water shed in Alaska as to evaluate the impact of fire to permafrost condition. By the different degree of forest fire to permafrost. On the spot investigation thermal conductivity of uppermost humic layers was affected by fire degree. The reciprocal of the humic or arganic layer thickness and thermal conductivity after fire impact are major factor of deepening of active layer. During fire experiments, direct measurements of ground temperature were conducted by means of small size data loggers. At some location, temperature of frozen layer increased up to 50C degrees. This amount of creased temperature was not due to heat conduction but perorated melt water into the ground.2) Aerosol Emission by boreal forest fire experimentAt the site of FROST FIRE experiment and Barrow, Alaska long term monitoring of aerosol emission was conducted. As the result of measurement, at Barrow in winter and early spring, soot, black carbon, arsenic, and vanadium which were produced by industry were traced, and the occurrence of Arctic Haze was proofed by these materials. At Poker Flat, high amount of black carbon was detected indicationg the influence of boreal forest fire.3) Emission of green house gases from permafrostBy the chamber method on the ground surface, direct influence of forest fire to the emission of green house gas were measured at Poker Creek Water shed. The flux of carbon dioxide from permafrost after fire impact decreased. On the contrary, Methane flux increased indicating of additional thaw of permafrost.