狭果秤锤树自然种群分布格局

  目的  揭示狭果秤锤树Sinojackia rehderiana自然种群不同生活史个体分布格局，为该种群的保护提供科学依据。  方法  以自然分布于江西省永修县的狭果秤锤树种群为对象，采用相邻格子样方调查法、空间代替时间和O-ring完全随机零模型法，对狭果秤锤树自然种群不同生活史阶段个体的空间分布格局和空间关联性进行分析，探讨其空间分布格局形成原因。  结果  狭果秤锤树径级结构和高度级结构完整，幼苗和幼树的数量在整个种群中占绝对优势，种群更新状态良好，属增长型种群。狭果秤锤树种群在从幼苗发育到成树的过程中，在小尺度上聚集分布，大尺度上为随机分布至均匀分布；随着龄级的增加，聚集分布趋势减弱。在较小的尺度上，不同生活史阶段个体表现出正相关或不相关，在较大的尺度上则表现为不相关或负相关；负相关性主要表现在幼苗与中树、幼树与中树、幼树与成树间（P < 0.05）。  结论  在自然状态下，狭果秤锤树分布格局受自身生物学特性和种内、种间竞争影响，幼苗和幼树生长受限但数量较多，种群目前尚未达到稳定状态。

Natural population distribution pattern of Sinojackia rehderiana in an evergreen broadleaf forest

  Objective  To reveal the spatial distribution pattern in different life cycle stages, and to provide a scientific basis for protection of Sinojackia rehderiana, which was naturally distributed in Yongxiu County, Jiangxi Province.  Method  To probe causes of the spatial distribution pattern formation, the adjacent lattice sampling method, the spatial sequence method instead of time sequence, and the O-ring Completely Random Zero Model method were used to analyze the spatial distribution pattern and spatial correlation of individuals in different life cycle stages of a natural population of S. rehderiana.  Result  The DBH class structure and height class structure of S. rehderiana were complete, and the number of seedlings and saplings occupied an absolute advantage for the entire population. Population renewal, which belonged to the growth population, was in a favorable condition. In the process of development from seedling to adult tree, the population of S. rehderiana had an aggregated distribution on a small scale, and had a random to uniform distribution on a large scale. As the age class increased, the aggregated distribution receded. On a small scale, at different life cycle stages of S. rehderiana, there was a significantly positive correlation or no correlation(P=0.05); however, on a large scale there was a negative association or no correlation. The spatial association between seedlings and middle-aged trees, saplings and middle-aged trees, and saplings and adult trees was significantly negative (P=0.05).  Conclusion  In a natural state, the distribution pattern of S. rehderiana was influenced by its own biological factors, intraspecific competition, and interspecific competition; seedling and sapling growth was limited but plentiful; and the population was not currently in a stable state.