The higher species richness of calcareous than siliceous communities is explained by lower competition in grasslands but higher facilitation in forests

We aim (i) at testing the hypothesis that higher species richness of calcareous than siliceous communities is due to lower competition in open habitats but to higher facilitation in forests, (ii) at disentangling the direct drivers of the higher facilitation of calcareous than siliceous forest canopies. To address these two aims, we conducted two transplant experiments on the two rock types in the South-west of France. In the first experiment, we transplanted, in dry and wet years, six understory species of contrasting light requirements, with and without neighbors in gaps and forest understories. In the second experiment, we transplanted six understory species of the two bedrock origins, in calcareous closed and semi-closed forests, in siliceous control and fertilized forests, and in calcareous and siliceous gaps. In the first experiment, competition was higher in gaps of siliceous than calcareous bedrocks during wet years, and facilitation by canopy trees was higher on calcareous than..., , # The higher species richness of calcareous than siliceous communities is explained by lower competition in grasslands but higher facilitation in forests

**Date of data collection:** 2016, 2018, 2019, 2020, 2023

**Information about geographic location of data collection:** Gironde department, France

**The file (Data.xlsx), created in 2025, includes 3 sheets:**

* Experiment 1:  RII values of the first experiment (Fig. 1).
* Experiment 2–Targets: Target responses in experiment 2 (Fig. 2-4).
* Experiment 2-Light: Light transmission in experiment 2 (Fig. 5).
* Experiment 2-Litterbags: Litter decay in experiment 2 (Fig. 7).
* Experiment 2–Temp–VPD: Temperature et VPD in experiment 2 (Fig. 6).

**There are no restrictions on the data.**

**Description of methods for data collection or generation**:

Target responses were collected in the field one year after each experiment. Light transmission and T and VPD were collected one day in the early summer. Litter decay was assessed using ...,

我们的研究目标有二：其一，验证假说：石灰质群落相较于硅质群落拥有更高的物种丰富度，源于开阔生境中的竞争压力更低，而森林生境中的促进作用更强；其二，厘清石灰质林冠相较于硅质林冠的促进作用更强的直接驱动因素。为达成这两项研究目标，我们在法国西南部的两种岩性基底上开展了两项移栽实验。在第一项实验中，我们于干旱年与湿润年分别移栽了6种光照需求迥异的林下物种，分别设置有邻体与无邻体两组处理，实验样地涵盖林隙与林下生境。在第二项实验中，我们移栽了源自两种岩性基底的6种林下物种，实验样地包括石灰质封闭林、半封闭林，硅质对照林、施肥林，以及石灰质与硅质林隙。第一项实验结果显示，湿润年硅质岩基底林隙中的竞争压力高于石灰质岩基底，而石灰质生境中林冠树木的促进作用更强……# 石灰质群落相较于硅质群落拥有更高的物种丰富度，这一现象可归因于草原生境中的竞争更低，而森林生境中的促进作用更强。
数据收集年份：2016年、2018年、2019年、2020年、2023年
数据采集地理位置：法国吉伦特省
本数据集文件（Data.xlsx）创建于2025年，包含以下5个工作表：
1. 实验1：第一项实验的相对相互作用指数（Relative Interaction Index, RII）值（对应图1）
2. 实验2-目标响应：第二项实验的目标响应指标（对应图2-4）
3. 实验2-光照：第二项实验的光照透射率（对应图5）
4. 实验2-枯落物袋：第二项实验的枯落物分解情况（对应图7）
5. 实验2-温度与水汽压亏缺：第二项实验的温度与水汽压亏缺（Vapor Pressure Deficit, VPD）（对应图6）
本数据集无使用限制。
数据采集与生成方法说明：
每项实验结束一年后，于野外采集目标响应指标数据；光照透射率、温度与水汽压亏缺数据于初夏的单日完成采集；枯落物分解情况通过……方法进行评估。