辽东山区次生林木本植物空间分布

森林木本植物的空间格局有助于揭示群落结构的形成机制与潜在的生态学过程,且对林分经营具有一定指导意义。在0—50 m尺度范围内综合分析了辽东山区4 hm2温带次生林样地多度10的树种空间格局。研究发现:(1)在完全随机零模型下,大部分树种呈现聚集格局,聚集格局树种的比例随尺度增加而降低;在32 m的较大尺度下,随尺度增加,随机和规则格局成为树种分布的主要形式;(2)在异质性泊松过程零模型下,55.9%的树种呈现随机格局,其余大部分树种在10 m的尺度下呈现聚集格局,且随尺度增加,规则格局成为主要形式;(3)在完全随机零模型下,树种属性(林层、径级和多度)显著地影响种群聚集度,而在异质性泊松过程零模型下,树种属性对种群聚集度不存在显著影响。综上,生境异质性、扩散限制和树种属性部分解释了辽东山区次生林木本植物空间分布格局,相对而言,生境异质性的效应更为突出。研究结果有助于揭示次生林群落生物多样性的维持机制。

Distribution patterns of woody plants in a secondary forest in the montane region of eastern Liaoning Province, China

Secondary forests comprise the main forest resource in China. These secondary forests maintain the species composition and habitat of primary forests but differ markedly in terms of structural composition, tree growth, productivity, forest environment, and ecological function. In the montane region of eastern Liaoning province, secondary forests are gradually formed through the destruction of broad-leaved Korean pine forests and they cover an area of 1.2×10⁷ hm², representing 84% of the total forest area. Secondary forests play important roles in soil and water conservation, climate regulation, agricultural production, and economic revitalization of old industrial sites. The spatial pattern of these forests is derived from the combined effects of biological characteristics, interspecific or intraspecific relationships, and environmental conditions, and it is an indicator of the adaptation of populations to environmental resources and ecological processes. The spatial distribution pattern reflects the processes of seed dispersal limitation, competition, habitat heterogeneity, etc. Evaluation of the distribution patterns of woody plants facilitates elucidation of the mechanisms involved in determining community structure and underlying ecological processes in forests. In the present study, we analyzed the distribution patterns of species with more than 10 individuals at spatial scales of 0-50 m in a 4 hm² temperate secondary forest plot located in the montane region of eastern Liaoning province. First, we found that most species showed aggregated spatial patterns under complete spatial randomness null models. The proportion of species exhibiting aggregated spatial patterns decreased with spatial scale, whereas the proportion of species exhibiting random or regular spatial patterns increased with spatial scale and mainly occurred at a scale of >32 m. Second, we found that 55.9% of species showed random or regular patterns under heterogeneous Poisson process null models, whereas the remaining species showed aggregated patterns at a scale of < 10 m. The proportion of species exhibiting random or regular spatial patterns increased with spatial scale and mainly occurred at a scale of > 10 m. Finally, we found that, under complete spatial randomness null models, species attributes (canopy layer, mean DBH, and abundance) clearly influenced the population aggregation; under heterogeneous Poisson process null models, species attributes had no significant influence on the population aggregation. Taken together, our results indicate that the distribution patterns of woody plants in secondary forests in the montane region of eastern Liaoning province may be partially explained by seed dispersal limitation, species attributes, and, in particular, habitat heterogeneity. Our findings provide a valuable insight into the mechanisms of biodiversity maintenance in secondary forests.