Research on the soil seed bank and seedling renewal of different populations of Berberis atrocarpa in the Western Tianshan Wild Fruit Forest

The soil seed bank and seedlings of Berberis atrocarpa Schneid. from three wild populations (Huocheng, Xinyuan and Tekesi) within the Western Tianshan Wild Fruit Forest were surveyed. We collected 54 soil samples, which were taken back to the laboratory to collect B. atrocarpa seeds. Results showed that there were no significant differences in the B. atrocarpa seed quality from the three populations. Intact seeds from the seed banks of the Huocheng, Xinyuan and Tekesi populations accounted for 51.6%, 49.4% and 54.1% of the total seeds, respectively. The vertical distribution of the B. atrocarpa seeds was characterized by the accumulation of 98.4% (Huocheng), 97.4% (Xinyuan) and 100% (Tekesi) of whole seeds in the litter layer, with no seeds found in the 5-10 cm soil layer. The horizontal diffusion distance of soil seeds gradually increased with the increase in slope. The B. atrocarpa seedlings in the Huocheng, Xinyuan and Tekesi populations were all root saplings, which allowed the seedlings to spread 100 cm or more from the mother plant. Grade Ⅱ seedlings (20-40 cm) accounted for the largest number (~50% of total seedlings). The transformation rate of Grade Ⅰ seedlings (0-20 cm) to Grade Ⅱ seedlings (20-40 cm) was 100% in all three populations. The conversions between the height stages of Ⅱ and Ⅲ (40-60 cm) in the Huocheng and Xinyuan populations were 29% and 32%, respectively, which were significantly lower than the 78% in the Tekesi population. Results showed that the B. atrocarpa seeds in the Western Tianshan Wild Fruit Forest were easily retained on the surface of the soil and the seed mildew rate in the soil was high, which may help explain the difficulty in the natural regeneration of B. atrocarpa.