Title: Soil Moisture Observations under Different Vegetations in a Boreal Humid Climate.
Abstract: Soil moisture was observed in situ for three years (1992-1994) to compare the effect of different vegetations (forest, grassland and wheat field) on soil moisture under the same meteorological conditions. The observation sites were located in a boreal humid climate where snow covers for about four months annually. The soil moisture was measured by the heat-probe method (Kasubuchi, 1992). It could measure the soil moisture automatically and continuously even under the snow covered condition. Seasonal variations of the soil moisture was characterized into three stages; from thawing to active vegetation (spring to summer), rainy (autumn) and snow covered (winter) period. The soil moisture and temperature were much influenced by the active time and the root system of each vegetation. Differences in soil moisture among the years depended on the meteorological conditions which affected the vegetation growth. From these observations, it became clear that the soil moisture and the soil temperature were affected not only by meteorological conditions but also by the vegetations.