Lusk Christopher H, Kelly Colleen K
Departamento de Botánica, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
Division of Biodiversity and Ecology, School of Life Sciences, University of Southampton, UK.
New Phytol. 2003 Jun;158(3):535-541. doi: 10.1046/j.1469-8137.2003.00760.x.
• The safe site concept could have utility in community ecology if predictive relationships between plant traits and safe site characteristics could be identified. Here we examine the proposal that the nature and relative abundance of safe sites are systematically related to seed size, in an assemblage of 17 woody species in a temperate forest. • We compared the degree of association of seedlings of each species with elevated microsites, and examined life-history correlates of this variation. • Seed size explained 45% of interspecific variation in percentage of seedlings growing on logs and other elevated substrates. Neither specific leaf area nor an index of light requirements gave significant increases in explanatory power. Phylogenetically independent contrasts gave a similar, but weaker, relationship with seed size. Most small-seeded species were overrepresented on elevated microsites, whereas two large-seeded taxa were underrepresented on these substrates. Safe sites of small-seeded species were therefore more spatially restricted than those of large-seeded taxa, as elevated surfaces occupied only 8% of the forest floor. • Safe site differentiation may help to explain the wide range of seed size present within many communities, as well as species coexistence in forests.
• 如果能够确定植物性状与安全位点特征之间的预测关系，那么安全位点概念在群落生态学中可能具有实用价值。在此，我们研究了这样一个提议：在一个温带森林中由17种木本植物组成的集合里，安全位点的性质和相对丰度与种子大小存在系统关联。
• 我们比较了每个物种的幼苗与高微生境的关联程度，并研究了这种变异的生活史相关性。
• 种子大小解释了在原木和其他高底物上生长的幼苗百分比种间变异的45%。比叶面积和光照需求指数均未显著提高解释力。系统发育独立对比与种子大小呈现出相似但较弱的关系。大多数小种子物种在高微生境上的占比过高，而两个大种子类群在这些底物上的占比过低。因此，小种子物种的安全位点在空间上比大种子类群的安全位点受到的限制更大，因为高表面仅占林地的8%。
• 安全位点分化可能有助于解释许多群落中存在的广泛种子大小范围以及森林中的物种共存现象。
