辽东山区次生林乔木幼苗分布格局与种间空间关联性

在辽东山区次生林建立4 hm^2样地(200 m×200 m),研究0~50 m尺度范围内乔木幼苗分布格局及种间空间关联性.结果表明:在完全随机零模型下,0~20 m尺度上,95%的树种呈现聚集分布格局;0~16 m尺度上,19个树种呈现聚集分布;随着尺度的增加,聚集分布树种的比例逐渐减少,50 m尺度上,随机分布成为树种分布的主要形式;在异质性泊松过程零模型下,0~24 m尺度上,5%的树种呈现聚集分布,26~50 m尺度上,42%和58%的树种呈现随机和均匀分布.在完全随机零模型下,正相关树种对比例最高,且在50 m尺度下呈现正相关、负相关、无相关3种相关性的树种对比例相同;在异质性泊松过程零模型下,树种对主要呈现负相关,且随尺度增大,负相关的树种对比例逐渐升高.种子扩散限制和生境异质性在某种程度上解释了乔木幼苗的聚集分布格局,乔木幼苗强烈的聚集分布又促使种间空间关联性密切,更新群落稳定性较差.

Spatial pattern and interspecific spatial association of tree seedlings in a secondary forest in montane region of eastern Liaoning Province,China.

We established a 4 hm²(200 m×200 m) temperate secondary forest plot in the montane region of eastern Liaoning Province, China, and analyzed the spatial patterns and interspecific spatial associations of tree seedlings at scales of 0-50 m. The results showed that under complete spatial randomness null model, 95% of the species at the scale of 0-20 m showed a significant aggregation pattern, and 19 species at the scale of 0-16 m showed an aggregation pattern. The proportion of species exhibiting aggregated patterns decreased with the spatial scale. At the scale of 50 m, the random distribution pattern became the main form of tree species distribution. Underheterogeneous Poisson process null model, 5% of the species at the scale of 0-24 m showed a significant aggregation pattern, and 42% and 58% of the species at the scale of 26-50 m showed a random distribution and regularity patterns, respectively. Under complete spatial randomness null model, the proportion of species pairs of positive correlation was the highest, and at the scale of 50 m, the proportion of species pairs showed positive correlation, uncorrelated and negative correlation tended to be equal. Under heterogeneous Poisson process null model, species pairs mainly showed negative correlation, and the proportion of species pairs exhibiting negative correlation increased with spatial scale. The results implied that seed dispersal limitation and habitat heterogeneity could explain the aggregation pattern of tree seedlings. The strong aggregation of tree seedlings also contributed to close interspecific spatial associations and poor stability of the regeneration community.