Abstract:
In order to explore the difference and influencing factors of the number of regenerated seedlings of Pinus schrenkiana on different decomposed grades of fallen wood, the relationship between the number and height levels of regenerated seedlings on different decomposed grades of fallen wood, and the water content, surface area, slope, slope direction and elevation of fallen wood were investigated respectively. The results showed that the probability of seedlings appearing on fallen wood with different decay grades was different, but the seedlings survival rate increased with the increase the decay grade of fallen wood. The height level structure of fallen wood seedlings with different decomposition grades showed obvious growth characteristics, with seedlings at height of 0-5 cm being the most. The water content of fallen wood had a significant impact on the number of seedlings on grade Ⅰ and grade Ⅱ decayed fallen wood(P<0.05), while the surface area of fallen wood had a significant impact on the number of seedlings on grade Ⅱ, Ⅲ and Ⅳ decayed fallen wood(P<0.01), but the slope and altitude had no significant impact on the number of regenerated seedlings on each grade of decayed fallen wood(P<0.05). Further analysis of the influencing factors on the number of seedlings at different height levels showed that water content had a very significant impact on the number of A
1(0-5 cm) and A
2(5.1-10.0 cm) height level regenerated seedlings on fallen wood with grade Ⅱ decay(P<0.01), and the surface area of fallen wood had a significant impact on the number of A
1 height level seedlings on fallen wood with grade Ⅱ and Ⅲ decay(P<0.05); On the fallen wood with grade Ⅳ decay, these factors had no significant impact on the number of regenerated seedlings at different height grades(P<0.05). The surface area and slope direction of fallen trees had a significant impact on the number of dead seedlings on fallen trees. The water content on low-level decomposed fallen wood was the main factor affecting the number of regenerated seedlings, while for high-grade fallen wood, the surface area was the main factor. In contrast, seedlings with lower heights were more susceptible to the impact.