Functional traits of young seedlings predict trade-offs in seedling performance in three neotropical forests

Understanding the mechanisms that promote the coexistence of hundreds of species over small areas in tropical forest remains a challenge. Many tropical tree species are presumed to be functionally equivalent shade-tolerant species that differ in performance trade-offs between survival in shade and the ability to quickly grow in sunlight.
Variation in plant functional traits related to resource acquisition is thought to predict variation in performance among species, perhaps explaining community assembly across habitats with gradients in resource availability. Many studies have found low predictive power, however, when linking trait measurements to species demographic rates.
Seedlings face different challenges recruiting on the forest floor and may exhibit different traits and/or performance trade-offs than older individuals face in the eventual adult niche. Seed mass is the typical proxy for seedling success, but species also differ in cotyledon strategy (reserve vs photosynthetic) or ..., This dataset combines seedling demographic performance with leaf, stem, and root functional traits also collected on seedlings.  More details on data collection and processing are available in Metz et al. Journal of Ecology.

Seedling dynamics data are collected in networks of 1-m2 plots in large (16-50 ha) Forest Dynamics Plots at each of three Neotropical forests: Yasuní, Ecuador; Luquillo, Puerto Rico; and Barro Colorado Island, Panama.  Each year in each plot, we tag and measure all seedlings of woody species (including trees, shrubs, palms, and lianas), identify all newly recruited seedlings, and determine the fate of previously tagged seedlings. We examined survival and growth across the first year for newly recruited seedlings from multiple cohorts in the longitudinal study at each site.  

Functional traits were quantified on young, field-harvested seedlings at each site. 
, , # Seedling functional traits and demographic performance from three Neotropical forests

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This data table contains functional trait measures and growth and survival for seedlings from species in three Neotropical forests. Different subsets of species were used in different analyses in Metz et al. based on sample size or the availability of different suites of traits, as described in the text.

## Description of the data and file structure

Each row is a species at one of three study sites. Columns are as follows. Each of these is described in much further detail in the accompanying article.

1. *site*, categorical, values are Yasuni, Luquillo or BCI, depending on the study site
2. *sp*, categorical, values are 4-6 letter codes for the seedling species use. Codes are those used in the Forest Dynamics Plot at each site, or as described in the seedling demography datasets archived in the Environmental Data Initiative repository
3. *SLA*, numeric, specific leaf area; units are dm2/g or ...

理解热带森林中小尺度区域内上百个物种共存的维持机制仍是一项挑战。诸多热带树木物种被认为是功能等价的耐阴物种，其在遮阴环境下的存活能力与光照充足环境下快速生长的能力之间存在性能权衡差异。

与资源获取相关的植物功能性状变异，被认为可预测物种间的性能差异，或可解释资源可用性梯度生境下的群落组装机制。然而，诸多研究发现，将性状测量结果与物种种群动态速率相联系时，预测能力往往较低。

幼苗在林床完成定居时面临迥异的生存挑战，其展现出的性状与/或性能权衡，可能与成熟个体在最终成体生态位中所面临的情况有所不同。种子质量通常被用作幼苗存活成功的替代指标，但不同物种在子叶策略（储备型 vs 光合型）上也存在差异……。本数据集将幼苗种群动态性能与同期采集的叶片、茎秆和根系功能性状相结合。有关数据采集与处理的更多细节可参见Metz等人发表于《Journal of Ecology》的研究论文。

幼苗动态数据采集于三个新热带森林的大型（16-50公顷）森林动态样地（Forest Dynamics Plots）内的1平方米样方网络中，这三个样地分别位于厄瓜多尔的亚苏尼（Yasuní）、波多黎各的卢奎洛（Luquillo）以及巴拿马的巴罗科罗拉多岛（Barro Colorado Island）。每年，研究团队会对每个样方内所有木本物种（包括乔木、灌木、棕榈和藤本）的幼苗进行标记与测量，鉴定所有新定植的幼苗，并确定此前已标记幼苗的存活状态。本纵向研究针对每个样地的多个同龄幼苗群，分析了新定植幼苗在头一年的存活与生长情况。

功能性状的量化基于各研究点野外采集的幼年幼苗。

# 来自三个新热带森林的幼苗功能性状与种群动态性能

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本数据表包含来自三个新热带森林物种幼苗的功能性状测量值，以及其生长与存活数据。正如论文中所述，在Metz等人的不同分析中，基于样本量或不同性状组合的可获得性，会使用不同的物种种群子集。

## 数据与文件结构说明

每一行代表三个研究样地中某一物种的数据。各列说明如下，详细描述可参见配套论文：
1. *site*（样地）：分类变量，取值为"Yasuni"、"Luquillo"或"BCI"，对应不同研究样地
2. *sp*（物种代码）：分类变量，为4-6位字母编码，代表研究中使用的幼苗物种。该编码采用各森林动态样地内的标准编码，或参照环境数据倡议（Environmental Data Initiative）仓库中存档的幼苗动态数据集所使用的编码
3. *SLA*（比叶面积，specific leaf area, SLA）：数值型变量，单位为dm²/g或……