Abstract: A plot (100 m×70 m) of Picea crassifolia stand was set up in Tianlaochi catchment of the Qilian Mountains, to analyze the spatial distribution pattern of different age classes and the spatial correlation based on point pattern analysis. The results showed that: (1) The age structure of P. crassifolia was relatively stable, being in a slight growing trend. (2) The ageclass Ⅰ showed aggregated distribution at different spatial scales; the ageclass Ⅱ showed aggregated distribution within 0-31 m, while showed the random distribution at >31 m scale. An aggregation distribution pattern was found at scales from 6-24 m, and random distribution patterns at the other scales for the ageclass Ⅲ individuals. On the whole, the spatial pattern showed random distribution with the increase of P. crassifolia’s age. (3) The correlation between the ageclass Ⅰ and the ageclass Ⅱ was significantly negative at 0-20 m spatial scale, gradually weakened at 20-23 m, but became positive over 23 m. The ageclass Ⅰ and ageclass Ⅲ individuals presented significantly negative correlations at all spatial scales. Ageclass Ⅱ and ageclass Ⅲ individuals showed negative correlations at any scale. Based on the large number and gathered distribution of young individuals at a small scale, we should take thinning to reduce the survival pressure and expand living space of remaining individuals, from a longterm perspective.

Key words: moss crust, net soil N mineralization rate, close-top tube incubation, seasonal dynamics.