Edaphic variation and the mesoscale distribution of tree species in a neotropical rain forest
Edaphic variation and the mesoscale distribution of tree species in a neotropical rain forest
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DOI：
10.1046/j.1365-2745.1998.00238.x
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发表时间：
1998-02-01
影响因子：
5.5
通讯作者：
Read, JM
中科院分区：
文献类型：
--
作者：
Clark, DB;Clark, DA;Read, JM
1在短环境梯度上的当地土壤因素是否影响热带雨林树种的分布和丰富度？我们通过研究中美洲哥斯达黎加高地古热带雨林景观中树种对土壤类型、地形位置和坡度的响应来解决这个问题。2研究区域覆盖了216公顷的非沼泽古树，包括山脊到沼泽连带、小流域和冲积梯田等复制景观单元。现有的土壤地图是通过沿规则间隔的网格进行额外采样来细化的。定义了三个土壤单元：玄武岩母质原地风化形成的残留土壤；早期洪水形成的旧冲积阶地土壤；以及溪谷土壤。在一项长期的人口统计学研究中，使用地理信息系统对9个树种的2190个立地后个体进行了土壤类型分配。野外测量了地形位置和坡角。3利用433个均匀分布的样点的数据生成预期的土壤变量分布，并将其与每个土壤类别中每个物种的个体数量进行比较。4在9个物种中，有7个物种在土壤类型之间存在非随机分布，其中6个物种具有地形位置，4个物种具有坡角等级。5通过考虑景观的古老生长特征和土壤单元之间频繁扩散的证据，分析了什么是独立的建立样本的问题。仅用直径4厘米的个体重新分析物种分布表明，原始分析的结果是稳健的。6土壤类型(残留与旧冲积)与直径生长没有显著关系。3种树种在不同土壤类型间的径级分布随直径的增大而有显著差异。7热带雨林树种在旱地土壤上往往沿相对较短的土壤梯度呈非随机分布。未来的研究应该增加分析的物种数量和空间尺度，纳入对土壤变量的更好分析，并包括识别产生这些非随机分布的生态过程的实验。
1 Do local edaphic factors over short environmental gradients affect the distribution and abundance of tree species in tropical rain forests? We addressed this question by examining the responses of tree species to soil type, topographic position and slope angle in an upland old-growth tropical rain forest landscape in Costa Rica, Central America.2 The study area covered 216 ha of non-swamp old growth and included replicated landscape units such as ridgetop to swale catenas, small watersheds, and alluvial terraces. An existing soils map was refined using additional sampling along a regularly spaced grid. Three soil units were defined: residual soils derived from in-place weathering of basaltic parent material; old alluvial terrace soils formed by precontemporary flooding; and soils of stream valleys. A Geographic Information System was used to assign soil type to 2190 post-establishment individuals of nine tree species in a longterm demographic study. Topographic position and slope angle were measured in the field.3 Data from 433 regularly spaced sample points were used to generate an expected distribution of edaphic variables, which was compared with the number of individuals of each species in each edaphic category.4 Non-random distributions among soil types were found for seven of the nine species, with topographic positions for six species, and with slope angle classes for four species.5 The issue of what constitutes an independent sample of establishment was analysed by considering the old-growth character of the landscape and evidence for frequent dispersal among edaphic units. A re-analysis of species' distributions using only individuals > 4cm diameter showed that results from the original analyses were robust.6 Soil type (residual vs. old alluvial) was not significantly related to diameter growth. Three species showed significant differences in size class distributions between soil types with increasing diameter.7 Tree species in tropical rain forests are frequently non-randomly distributed along relatively short edaphic gradients on upland soils. Future studies should increase the number of species and spatial scale analysed, incorporate better analyses of edaphic variables, and include experiments to identify the ecological processes that generate these non-random distributions.