2001 Volume 83 Issue 2 Pages 116-124
The physical properties of soil samples taken from Japanese cypress (Chamaecyparis obtusa Endl.) stand and clearcut areas of Japanese cypress was measured, and aggregate development was analyzed quantitatively by determining the aggregation index. The aggregation index was high in the soil with a crumb structure and a granular structure, and low in the soil with a blocky structure and a single-grain structure or when no structure was recognized. A positive correlation was observed between the aggregation index and the number of large pores ( ?? -6.2 kPa), and between the number of large pores and saturated hydraulic conductivity. It was shown quantitatively that when aggregates developed, the number of large pores increased and permeability became high. The relationship between the degree of aggregate development and physical properties of forest soil may be clarified by quantitative determination of a single value, the aggregation index. Therefore, it was found possible to formulate the relationship between the condition of aggregate development and other physical properties.
