2018 Volume 60 Issue 2 Pages 45-54
In this study, the effects of forest clearing were quantitatively investigated by monitoring the water content and ground temperature of the surface soils within and outside a cutover area. First, the soil types, microtopographical units, and surface soil thickness were determined, and then the soil water content and ground temperature as well as their seasonal changes were measured and compared at 34 points. Except for the winter, the soil water content and ground temperature showed quite different values between outside and within the cutover area; especially at a head slope, the difference reached nearly 10%. And more, within the cutover area, there was major difference between upper and lower slopes on soil water content. Drier condition was observed at the lower slopes where would be originally wetter condition; the authors visually confirmed weakly dried yellow soils (YC type) after digging some soil pits. In tropics, buffer zones are usually established along streams in mountainous area for the sake of controlling soil runoff. In case of clearing in sub-tropical areas including Okinawa Island, it is necessary to avoid felling and establishing buffer zone at lower slope where is easily dried.
