吉林蛟河不同演替阶段针阔混交林木本植物幼苗空间分布与年际动态

幼苗的空间分布对群落更新具有重要意义。于2011年夏季在蛟河地区3个不同演替阶段针阔混交林样地内共设置了451个种子雨-幼苗观测样站,并于2012—2014年对幼苗样方内胸径1 cm的木本植物幼苗进行了连续3a的调查。对木本植物幼苗的数量分布以及水曲柳(Fraxinus mandshurica)、五角枫(Acer mono)、杉松(Abies holophylla)和东北枫(Acer mandshuricum)4个主要树种幼苗与大树的空间关系及其年际变化进行了分析,并用Syrjala检验分析了样站尺度上幼苗密度、丰富度空间分布在年际间的差异。结果显示:(1)木本植物幼苗的数量分布在不同群落和年际之间都表现出明显的差异,样站尺度上3个样地内的幼苗密度存在着较大的空间变异性,而幼苗丰富度的空间异质性较低。表明幼苗分布的空间异质性对幼苗密度有着重要影响。(2)样站尺度上幼苗数量和物种数的空间分布在不同年份之间是存在差异的。在一定程度上证实了种子产量、扩散方式和群落组成对幼苗空间分布的影响。(3))从死亡幼苗与大树空间关系来看,4个主要树种的死亡幼苗与成树表现出相似的分布格局,这既表明成体植株的空间分布特征也能够影响幼苗的空间分布格局,也从侧面说明了负密度制约效应对幼苗空间分布的影响。

Spatial distribution and interannual dynamics of tree seedlings at different successional stages in a conifer and broad-leaved mixed forest in Jiaohe,Jilin Province,China

The spatial pattern of seedlings plays an important role in community regeneration. Our study was based on 415 seed-seedling census stations established in three large permanent field plots,each representing one of three successional stages in a conifer and broad-leaved mixed forest. We conducted three censuses from 2012 to 2014 for seedlings < 1 cm in diameter at breast height and analyzed the quantitative distribution of woody seedlings and the spatial relationship between seedlings and adult trees for four major species:Fraxinus mandshurica,Acer mono,Abies holophylla,and Acer mandshuricum. The Syrjala test was used to analyze interannual differences in the spatial pattern of the number of individual seedlings and the number of seedling species at the station level. Our results indicated that(1) there were obvious differences in the quantitative distribution of woody seedlings among communities and years. Seedling density exhibited substantial spatial variability at the station level,whereas spatial heterogeneity of seedling richness was low. These results indicated that spatial heterogeneity of seedling distribution had an important impact on seedling density.(2) Spatial pattern of the number of individual seedlings and the number of seedling species varied among years at the station level. This demonstrated the influence of seed production,dispersal method,and community composition on the spatial distribution of seedlings.(3) Judging from the spatial relationship between dead seedlings and adult trees,dead individuals of the four major seedling species exhibited a similar distribution pattern with that of adult trees,which indicated that the distribution pattern of adult trees might affect the distribution pattern of seedlings,. It further confirmed the negative density dependence of the spatial pattern of seedlings.