Abstract: In recent years, ancient trees of Cryptomeria japonica var sinensis in Western Tianmushan are declining due to attacks by diseases and insect pests, which were believed to be triggered by acid deposition. The physical and chemical features of soils to provide references for this opinion was analyzed. In this study, soil samples were collected along altitude from 350 m to 1 350 m, with the interval of 200 m. At each sampling site, soil samples were collected from three layers. Soil texture, humidity, bulk density, pH value, organic matter content, contents of total nitrogen and total phosphor were analyzed. Generally, percentage of coarse particles, soil humidity and organic matter content increased with increasing altitude. Soil bulk density and pH value had a declining trend with the increase in altitude. Total nitrogen and phosphor contents had no constant trend along altitude. Compared to the data of 1986 and 1995 years, significant decrease in pH value was observed, indicating a trend of acidification. The observed soil acidification provides evidence for the rapid decline in ancient trees of Cryptomeria japonica var. sinensis triggered by acid deposition.

Key words: soil properties, altitude, soil acidification, Western Tianmushan, soil properties, altitude, soil acidification