Abstract: [Objective] We present a spatial-explicit model of seedlings establishment for scattered individual trees of Pinus sylvestris var. mongolica, which describes the spatial pattern of seedling recruitments. This study will provide a basis for prediction of expanding trend and natural regeneration of Pinus sylvestris var. Mongolica.[Method] A new spatial-explicit seedling recruitment model was developed based on the Von Mises distribution and Weibull distribution. The proposed model was calibrated by the least square method based on the measurement dataset of 1 374 seedlings from 10 scattered individual trees of Pinus sylvestris var. mongolica located at Hulun Buir sandy land in Northeast China. The proposed model simulated the spatial pattern of seedlings from an isolated Mongolian Scots pine with the base diameter of 70 cm.[Result] 1)The spatial pattern of natural regeneration for scattered individual trees of Pinus sylvestris var. mongolica followed the Janzen-Connell hypothesis but had the specific direction. The azimuth of seedlings had two zones of 0°-127° and 216°-360°, and the distance of seedlings to the parent tree was 0.37-10.95 m; 2)The spatial-explicit seedling recruitment model consists of seedling number modules, azimuth modules and distance modules. Derived from the model, we found the mean directions of seedlings dispersal were 16° north by east, and the mean distances of seedlings dispersal were 5.37 m; 3) The simulated spatial pattern of seedling recruitment agreed well with the observed ones.[Conclusion] The distances between seedlings and parent tree followed the Janzen-Connell's hypothesis, but their azimuth had the specific direction. The success of seedling establishment requires low radiation.

Key words: forest dynamics, spatial pattern, spatial-explicit model, Janzen-Connell hypothesis, natural regeneration