Objective To explore the natural regeneration in Larix principis-rupprechtii plantation in Guandi Mountain, and explore the effect of gap size on regeneration.

MethodsIn this study, the density, growth status and spatial distribution of seedlings of Larix principis-rupprechtii under different gap sizes were investigated. The K2 function point pattern analysis was performed for exploring spatial pattern of seedlings under different gap sizes.

Results(1) The regeneration density and growth indices of Larix principis-rupprechtii were positively correlated with the increase of gap area (P < 0.05). Gap size had the most significant effect on sapling growth indexes (base diameter, height and age). The maximum mean values of growth indexes mostly appeared in gap grade I (20～50 m²), and the maximum mean values of seedlings and saplings density appeared in gap grade II (50～100 m²) and III (100～150 m²), respectively. (2) Saplings mostly distributed in the canopy projection area and canopy gap edge, and gradually distributed in the center of the gap. (3) In the gap of Larix principis-rupprechtii, most of the saplings were aggregated and distributed in small scale, and few saplings were evenly distributed.

Conclusion Gap size has a significant effect on regeneration of Larix principis-rupprechtii. Gap grade I (20～50 m²) is conducive to seedling establishment and germination. In addition, the gap area could be enlarged to grade II (50～100 m²) by human disturbance to promote seedling survival and sapling growth.