Abstract: By using O-ring statistics in point pattern analysis and Programita software, this paper studied the spatial distribution patterns and associations of different age-class individuals of Taxus chinensis var. mairei populations at Xianyu and Xiaxiang in the mountainous area of southern Anhui Province. The Xianyu population had a random spatial distribution at the scales from 2 m to 25 m but a clumped distribution at the scales ＜2 m, while the Xiaxiang population distributed randomly at all the scales. As for Xianyu population, its individuals of age-class I had a clumped distribution at the scales ＜5 m, while the individuals of elder age-classes tended to be non-randomly distributed at more scales than ＜5 m, which might be related to the features of population regeneration. With increasingly enlarged age-class differences, the spatial association between younger and elder age-classes individuals turned to be negative, but less spatial association was observed between adjacent age-classes individuals. Such a spatial relationship between different age-classes individuals of T. chinensis was beneficial to the effective use of resources. With the grow th of the individuals, T. chinensis population had a transition from clumped to random distribution.

Key words: Taxus chinensis var. mairei population, Programita software, point pattern analysis, spatial association, biological soil crusts, drought process, nitrate nitrogen, net nitrification rate.