亚热带-温带气候过渡区落叶阔叶林物种-生境关联分析

物种-生境关联分析有利于更好地理解物种共存理论和群落构建机制。根据秦岭落叶阔叶林25 hm²固定监测样地的调查数据,将树种分为幼苗、幼树和成树3个生活阶段,利用Torus-translation检验方法分析物种与不同生境类型之间的关联性。结果表明: 生境对各物种的影响不同。与高坡显著关联的物种数最多,其中95.7%为负关联;与低坡呈负相关的物种占89.5%;与山脊呈显著负关联的物种占90.9%;物种与高谷生境多存在显著正关联,呈负相关的只有1种,占0.03%。物种在幼苗、幼树和成树阶段与生境分别存在80、44和23个关联,表明幼苗阶段对生境的依赖程度更大。幼苗阶段的物种中有38个(占总物种数的90.5%)至少与一类生境存在显著的关联性;幼树阶段有25个(占总物种数的58.1%)至少与一类生境存在显著关联;成树阶段只有17个(占总物种数的39.5%)至少与一类生境存在显著关联。同一生境对不同生活史阶段物种的影响存在差异,到生活史阶段后期,生境的影响逐渐减弱。由于特定的环境需求,多数物种在不同生活史阶段表现出不同的生境偏好。

Species-habitat association of a deciduous broadleaved forest in the subtropical and tempe-rate transition zone

The species-habitat association analysis facilitates a better understanding of species coexis-tence and community assembly. Here, all trees in a 25-hm² broadleaved deciduous forest plot in the Qinling Mountains of North-central China were classified into three life stages (i.e., seedling, sapling, and adult). The Torus-translation test was used to examine the species-habitat association. The results showed that the association of species with habitats varied across different species. Most species were significantly associated with high slopes, 95.7% of which showed negative association. 89.5% and 90.9% of tree species were negatively associated with low slopes and ridges, respectively. Most species had positive association with high valley, with only one negative association (0.03%). There were 80, 44 and 23 significant associations with habitats at seedling, sapling and adult stages, respectively, indicating that a greater dependence of seedlings on habitat. 38 species at seedling stage and 25 species at the sapling stage were associated with at least one habitat type, while only 17 species at the adult stage were significantly associated. The effects of habitat on species varied across life stages, showing a weaker species-habitat association at the later stage. Due to the specific environmental demands, most species showed different habitat preferences across life stages.