秦岭山地锐齿栎次生林幼苗更新特征

Characteristics of seedlings regeneration in Quercus aliena var. acuteserrata secondary forests in Qinling Mountains

分析了秦岭山地锐齿栎次生林群落乔木及木本幼苗物种特征值、更新生态位宽度及不同影响因子下(包括林分密度、坡向、海拔等)乔木的更新动态。结果表明,乔木层物种有25种,锐齿栎占有明显的优势,重要值为149.18%;其次为华山松(Pinus armandii)和千斤榆(Carpinus cordata)等。更新层共有木本植物41种,其中乔木种有28种,占所有木本植物总数量的68%,优势种有青蛙皮槭(Acer grosseri)、木姜子(Litsea pungens)等。林下有丰富的幼苗库,更新方式以实生为主;分析了10种更新优势乔木种群的生态位宽度,同种幼树种群生态位宽度均大于幼苗种群生态位宽度。幼苗种群生态位宽度从大到小依次为榛子(Corylus heterophylla)、锐齿栎、青蛙皮槭等。幼树种群生态位宽度从大到小依次为榛子、青蛙皮槭、锐齿栎等;林分密度对林下乔木幼苗和幼树数量影响不同。当林分密度从720增加到1460株/hm2时,幼苗密度逐渐增大。随后随着林分密度的增加,又呈现出减少的趋势。而幼树密度随着林分密度增加一直呈现出减少的趋势。坡向对锐齿栎次生林林下乔木幼苗和幼树的影响各异,阳坡(南偏西3°)均利于幼苗和幼树的更新。南偏西45°林分内,幼苗密度急剧减少。随着坡向转为阴坡,幼苗密度又逐渐增加。而幼树密度逐渐减少。当海拔从1083 m增加到1547 m时,幼树密度逐渐增加。随后,随着海拔增加到1882m,幼树密度则逐渐减小。而幼苗密度随着海拔的增高一直呈现减小的趋势。

Quercus aliena Blume vat. acuteserrata Maxim. ex Wenz. is an important dominant species in temperate mid- elevation mountainous areas of China with significant functions in water resource conservation and ecological stabilization in forested ecosystems. Forty-two plots, including 210 subplots, were used to document the occurrence of trees, saplings, woody seedlings and habitat characteristics for this tree and associated woody species in a second growth forest in the Qinling Mountains in 2010. We analyzed the important values of trees, saplings and woody seedlings, regeneration niche breath, and tree regeneration dynamics under different conditions, including stand density, aspect, and altitude in Q. aliena var. acuteserrata secondary forests. The results show Q. aliena var. acuteserrata had an important value of 149.18% with none of the other 24 woody tree species in the tree layer approaching that level of importance. The subdominant species in the tree layer were Pinus armandii Franch. and Carpinus cordata Blume. 25 tree species of the 41 woody species in the regeneration layer. The woody plants in the regeneration layer were abundant with trees seedlings dominating. This appearsto be beneficial to the optimization of the community structure and function. The dominant seedling species were Acer grosseri Pax, Litsea pungens Hemsl. , and others. Seedlings of these two species were abundant in the regeneration layer with their height and age class lower than the dominant species. The height class of seedlings and of Q. aliena var. acuteserrata secondary forest shows that woody plants regenerated vigorously saplings in the understory The biological chain of seedling to sapling was complete. Most regeneration was from seedlings rather than stump sprouts. We analyzed ten kinds of dominant regeneration tree populations. The regeneration niche breath of the sapling population was higher than that of seedling population for the same tree species which indicated the saplings has the broader use of community resources. Theniche breath sequence from high to low seedling population was： Corylus heterophylla Fisch. ex Trautv. 〉 Q. aliena var. acuteserrata 〉 A. grosseri 〉 other species. For saplings it was Corylus heterophylla 〉 A. grosseri 〉 Q. aliena var. acuteserrata 〉 other species. Stand density had different effects on the density of saplings and seedlings. Sapling and seedling density increased with the stand density from 720 trees/ha to 1460 trees/ha, then decreased with the stand density increasing. The saplings density decreased continuously as the stand density increased. The direction of slope had various effects on the seedlings and saplings. A sunny SW facing slope of 3 ° was the most beneficial to seedlings and saplings. As the slope changed direction to create a shady slope, the seedlings density increased and the sapling density decreased. Sapling and seedling density c 1547 m, then decreasing with hanged with altitude. The saplings density increased as altitude increased from 1083 m to altitude up to 1882 m. The seedlings density increased from lower altitude to higher altitude