In order to understand the effects of soil condition on tree growth and nutrient cycling, we monitored the changes in stem diameter and analyzed the nutrient content of current-year needles and leaf litter of Picea glehinii growing in Gray Upland and Peat soils. Stem diameter showed diurnal changes that reflected transpiration and water uptake in both soils. However, the increase in stem diameter was larger in Gray Upland soils than in Peat soils, probably due to the longer growing period of Picea glehinii in the former than in the latter. During a rainy day within the growing period, the average increase in stem diameter was 35 μm d^<-1> in Gray Upland soils and 23 μm d^<-1>in Peat soils. These results suggested that the excessive soil water content in Peat soils weakened the response to rainfall of Picea glehinii. The poor soil water condition in Peat soils was reflected in the minimal growth of Picea glehinii in this soil. Litterfall production in Gray Upland soils was more than twice of that in Peat soils and the C/N ratio of the litterfall in Peat soils was statistically higher than that of Gray Upland soils. The poor soil water condition in Peat soils may have restricted the growth and nutrient uptake of Picea glehinii, which resulted to a low production of litterfall and its high C/N ratio. Results of this study have shown that soil conditions affect tree growth and nutrient cycling.
