长白山阔叶红松林乔木幼苗年际动态及影响因素

Interannual seedling dynamic and influencing factors on seedling survival of tree species in a broadleaved Korean pine( Pinus koraiensis) mixed forest in Changbai Mountains,northeastern China

以长白山原始阔叶红松林样地为平台,对样方中胸径<1 cm的乔木幼苗进行监测,基于2006—2014年的调查数据对该群落中乔木幼苗的物种组成、数量特征、新生与死亡动态以及影响幼苗存活的因素进行分析。结果表明:1)群落乔木幼苗近10年物种组成变化较小,每年都可以监测到9个常见种。2)幼苗个体的大量萌发和大量死亡导致群落乔木幼苗数量有较大的年际变化,其中最多年份幼苗密度可达38.9株/m2,而最少年份仅有3.8株/m2。3)不同年份群落乔木幼苗年龄组成中1年生幼苗数量最多,部分年份略有差异。随着幼苗年龄的增加,幼苗数量不断减少。幼苗总体数量同幼苗新生数量动态变化是一致的,幼苗死亡的峰值较幼苗总体峰值有1年的时滞。4)群落水平上幼苗存活与同种大树胸高断面积和林冠开阔度呈显著正相关,与异种幼苗邻体呈显著负相关。群落中幼苗个体大量萌发和大量死亡的现象证明该群落存在明显的更新限制,在一定程度上有利于群落的物种共存。近10年的幼苗监测有助于我们更加准确地认识群落更新过程,因而长期的动态监测十分必要。

This paper is to understand the interannual dynamic and influencing factors on seedling survival in a broadleaved Korean pine（ Pinus koraiensis） mixed forest in northeastern China. 100 seedling monitoring（ 1 m × 1 m） quadrats were set at Changbai Mountains,of which DBH 〈1 cm seedlings in quadrats were tagged,measured and identified to the species. Based on seven censuses from 2006 to 2014,we analyzed the species composition and interannual dynamic of all seedlings,especially for seedling recruitment and death. We examined the relative importance of biotic neighborhood and habitat heterogeneity on seedling survival by using generalized mixed linear model. A total of 13 tree seedling species were identified and recorded. Results showed that： 1） there were a little difference of the species composition from 2006 to2014,and we monitored 9 common seedling species each year. 2） There were great temporal fluctuation in seedling density,of which the highest was 38. 9 seedlings per m2 and the lowest was 3. 8 seedlings per m2. 3） Tree seedlings had a large number of regeneration and death every year. On the age structure of arbor seedlings in the community,1-year-old seedlings had most individuals in most cases,some years had a little difference. With the increase of seedling age,seedling numbers decreased gradually. The dynamic change of total seedling numbers agreed with that of regenerated seedling numbers. The seedling death peak was 1 year time delay than the seedling total peak. We found that both biotic neighbors and habitat heterogeneity had significant effects on the seedling survival at community level. 4） The basal area at breast height of conspecific adult and canopy openness had significant positive effect on seedling survival,while heterospecific seedling neighbors showed negative effect. Our results suggested that the majority of tree species in Changbai Mountains were recruitment-limited,which might have important consequences for species coexistence. High temporal variability in seedling density emphasized the importance of long term studies to understanding of forest dynamics. Nearly a decade of seedling monitoring can make us understand the community regeneration process more accurately.