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西天山雪岭云杉不同腐解等级倒木的更新幼苗数量特征及其影响因素

Quantitative Characteristics and Influencing Factors of Regeneration Seedlings of Different Decay Grades of Pinus schrenkiana, Western Tianshan Mountains

  • 摘要: 为探究雪岭云杉(Pinus schrenkiana)更新幼苗数量在不同腐解等级倒木上的差异性以及影响不同腐解等级的倒木上更新幼苗数量具体因素,研究了不同腐解等级倒木上雪岭云杉幼苗数量和高度级组成与倒木含水量、倒木表面积、坡向、坡度及海拔的关系。结果表明:不同腐朽等级倒木上幼苗的出现概率不同,但随着倒木腐解等级的增加,幼苗的存活率也越大。不同腐解等级倒木幼苗高度级结构均为明显的增长型特征,以高度(h)为0 0.05)。进一步对不同高度级幼苗数量的影响因素分析表明,含水量对Ⅱ级腐解的倒木上的A1(0 0.05)。倒木表面积和倒木所处坡向对倒木上死亡幼苗的数量有显著影响。低等级腐解倒木上含水量是影响更新幼苗数量的主要因素,对高等级倒木而言则是表面积,相比之下,高度越低的幼苗,越容易受到影响。

     

    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 A1(0-5 cm) and A2(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 A1 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.

     

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