Abstract
In order to confirm a change in properties of surface volcanic deposit on the 2000 tephra mantled slope in a period of a large amount of volcanic gas emission from Miyakejima volcano, we observed surface soil micromorphological characteristics and investigated soil physical and chemical properties, of which we col-lected surface soil samples in 2002 and 2007. We also compared the 2002 sample with the 2007. These results suggested that volcanic deposit covered with litter decreased soil hardness in five years. Structural crust was found in the ground surface without litter where surface erosion occurred. Severe hardening of surface volcanic deposit (Index of soil hardness ＞17 mm) from 2002 to 2007 should be attributed to soil crust. Lime require-ment of the surface deposit with calcium carbonate and aeration method indicated that acidic deposits suffering from most severe volcanic gas and damage of the initial root growth could be due to Al toxicity in low pH. The results indicated that seeding work is difficult to recover vegetation under conditions of high-concentration volcanic gas.
