Structural diversity shifts from negative to positive associations with forest productivity via basal area, stand age, and precipitation thresholds

Understanding the relationship between biological diversity and ecosystem productivity is a central challenge in ecology. Structural diversity—the variation in size, height, and spatial arrangement of individuals within communities—has been proposed as a key driver of productivity, yet previous studies have reported mixed results, leaving its role in ecosystem functioning unclear. Clarifying the structural diversity and productivity relationship (SDPR) is essential not only for advancing ecological theory but also for informing biodiversity conservation, resource management, and climate adaptation strategies across ecosystems. Here, we utilized the USDA Forest Service Forest Inventory and Analysis (FIA) database, encompassing 95,602 trees within 3,307 plots throughout most types of forest ecosystems in the contiguous U.S. We investigated the variation of SDPR by analyzing the growth of existing trees under the main and interactive effects of structural diversity with basal area, stand a..., , # Data from: Structural diversity shifts from negative to positive associations with forest productivity via basal area, stand age, and precipitation thresholds

Dataset DOI: [10.5061/dryad.0gb5mkmdq](10.5061/dryad.0gb5mkmdq)

## Description of the data and file structure

We have five datasets for the analysis.

**FIA_Shade_Tolerance.xlsx**, a shade-tolerance metrics, ranging from 1-5 for the species in FIA data.

**tbl.fig.RData,** RData for figures.

**tbl.growth.Norm.DmgTree.Rdata,** Plot-level data w/o standardized variables.

**tbl.site.growth.site.dmgTree.Rdata,** Plot-level data w/ standardized variables.

**tbl.tree.MrgSbPlt.Rdata,** tree-level data after data curation in raw FIA data. Note that this tree-level data were aggregated to create plot-level data.

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**Descriptions**

**Code_JE.R:** Code that includes GAM developments and figures.

**FIA_Shade_Tolerance.xlsx**

* SpcsNm: Species Name (scientific names)
* Shade tolerance: degree of the shade-tolerance, ranging f...,

阐明生物多样性与生态系统生产力之间的关联，是生态学领域的核心挑战之一。结构多样性（Structural diversity）指群落内个体的大小、高度与空间排布的变异程度，此前被认为是驱动生产力的关键因子之一，但既往研究结论莫衷一是，导致其在生态系统功能中的角色仍不明确。明确结构多样性与生产力的关联（Structural diversity and productivity relationship, SDPR），不仅对于推动生态学理论发展至关重要，也可为各类生态系统的生物多样性保护、资源管理与气候适应策略提供科学依据。本研究依托美国农业部林务局森林资源清查与分析（Forest Inventory and Analysis, FIA）数据库，该数据集涵盖美国本土连续分布的3307个样地内的95602株林木，覆盖美国本土绝大多数森林生态系统类型。本研究通过分析现有林木在结构多样性与断面积、林龄……的主效应及交互效应下的生长情况，探究SDPR的变化规律。# 数据来源：基于断面积、林龄与降水阈值，结构多样性与森林生产力的关联从负向转为正向

数据集DOI：10.5061/dryad.0gb5mkmdq

## 数据与文件结构说明
本分析共包含5个数据集：
**FIA_Shade_Tolerance.xlsx**：包含FIA数据中各物种的耐阴性评分，评分范围为1至5。
**tbl.fig.RData**：用于生成图表的RData格式数据文件。
**tbl.growth.Norm.DmgTree.Rdata**：未进行变量标准化的样地级数据集。
**tbl.site.growth.site.dmgTree.Rdata**：已完成变量标准化的样地级数据集。
**tbl.tree.MrgSbPlt.Rdata**：经原始FIA数据整理后的单木级数据集。请注意，该单木级数据经聚合后得到样地级数据集。

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## 数据说明
**Code_JE.R**：包含广义加性模型（Generalized Additive Model, GAM）构建与图表生成的代码文件。
**FIA_Shade_Tolerance.xlsx**
* SpcsNm：物种名称（学名）
* 耐阴性：物种耐阴程度，评分范围为……