Plant community composition in response to litter removal in Riverside, California, USA, 2021-2023

Litter produced by exotic grasses is known to negatively impact native species through multiple mechanisms. While litter removal is a potential restoration tool to recover native species, the effects of litter removal on overall plant community structure are not well understood as most studies focus on native species recovery. In a litter removal experiment in Southern California, USA, we found that plant communities receiving litter removal treatment differed in species composition from control plots and had 4.4% higher native forb relative abundance and 7.0% higher exotic forb relative abundance, on average. These changes in exotic and native forb abundance with litter removal altered community structure by increasing overall Shannon diversity, while only having a modest positive effect on overall species richness. In contrast, we found no effect of litter removal on the species richness or Shannon diversity of native species. Taken together, these findings suggest that in herbaceous ..., Study Site
The experiment was located at a site on the University of California–Riverside campus in Riverside, California, USA (33.967º N, 117.323º W) where the mean annual temperature is 19 ºC and the mean annual precipitation is 238 mm. The site is at 400 m above sea level and is a north-facing slope that was formerly composed of Riversidean CSS dominated by native subshrubs Artemisia californica (California sagebrush; Asteraceae), Encelia farinosa (brittlebrush; Asteraceae), Salvia mellifera (black sage; Lamiaceae), Salvia apiana (white sage; Lamiaceae), Acmispon glaber (deerweed; Fabaceae), and Eriogonum fasciculatum (California buckwheat; Polygonaceae). These native subshrubs are present in small, scattered stands in the adjacent south-facing slopes but not at the experiment site. The experiment site is now an exotic annual grassland dominated by the invasive annual grass Bromus diandrus (ripgut brome; Poaceae) with interspersed exotic and native forbs.
Experimental Design
In 2021,..., , # Plant community composition in response to litter removal in Riverside, California, USA, 2021-2023

[https://doi.org/10.5061/dryad.3xsj3txrj](https://doi.org/10.5061/dryad.3xsj3txrj)

## Description of the data and file structure

This dataset contains our raw data table of species recorded at each sampling point within each plot; as well as several tables containing metrics of species areal cover, species diversity, functional group abundance, and species relative abundances calculated from the raw data, which were used in our analysis. Additionally, we have included a table with all of the species encountered in our study period (species list).

### Files and variables

#### File: plot\_species\_relabund\_matrix.csv

**Description:** A matrix of plots sampled at a time point and the relative abundance of all plant species observed (i.e., a site by species matrix).

##### Variables

* plot_in_year: the plot ID in the year of sampling, as well as the treatment. All plots were unmanip...

外来草本产生的枯落物已被证实可通过多种机制对本土物种产生负面影响。尽管枯落物移除是恢复本土物种的潜在修复手段，但目前学界对枯落物移除对植物群落整体结构的影响仍知之甚少——因多数相关研究仅聚焦于本土物种的恢复效果。在美国加利福尼亚州南部开展的枯落物移除实验中，我们发现：接受枯落物移除处理的植物群落，其物种组成与对照组样地存在显著差异；平均而言，本土非禾本科草本植物（forb）的相对丰度提升4.4%，外来非禾本科草本植物的相对丰度提升7.0%。枯落物移除带来的外来与本土非禾本科草本植物丰度变化，通过提升整体香农多样性（Shannon diversity）改变了群落结构，仅对物种丰富度（species richness）产生微弱的正向影响。与之相反，枯落物移除对本土物种的物种丰富度与香农多样性均无显著影响。综合来看，这些研究结果表明，在草本…… 研究样地
本实验的样地位于美国加利福尼亚州里弗赛德市加利福尼亚大学河滨分校校园内（北纬33.967°，西经117.323°），该区域年平均气温19℃，年平均降水量238毫米。样地海拔400米，为北向坡，原生植被为以本土亚灌木为优势种的里弗赛德型海岸鼠尾草灌丛（Riversidean CSS），优势亚灌木包括：加州蒿（*Artemisia californica*，加州山艾树；菊科Asteraceae）、灰毛银叶菊（*Encelia farinosa*，脆枝木；菊科Asteraceae）、黑鼠尾草（*Salvia mellifera*；唇形科Lamiaceae）、白鼠尾草（*Salvia apiana*；唇形科Lamiaceae）、鹿草（*Acmispon glaber*；豆科Fabaceae）以及加州沙拐枣（*Eriogonum fasciculatum*，加州荞麦；蓼科Polygonaceae）。上述本土亚灌木仅零散分布于邻近的南向坡地，本实验样地内并无此类植被。当前实验样地为入侵性一年生草本占优的外来一年生草原，优势入侵草本为断穗雀麦（*Bromus diandrus*，ripgut brome；禾本科Poaceae），样地内混杂分布有外来与本土非禾本科草本植物。
实验设计
2021年，…… # 美国加利福尼亚州里弗赛德地区枯落物移除对植物群落组成的影响，2021-2023

[https://doi.org/10.5061/dryad.3xsj3txrj](https://doi.org/10.5061/dryad.3xsj3txrj)

## 数据与文件结构说明
本数据集包含各样地内每个采样点记录的物种原始数据表；同时包含多张衍生数据表，涵盖基于原始数据计算得到的物种盖度、物种多样性、功能群丰度以及物种相对丰度等分析所用指标。此外，数据集还包含本研究周期内所有观测到的物种列表（species list）。

### 文件与变量说明
#### 文件：plot_species_relabund_matrix.csv
**描述：** 包含采样时间点样地与观测到的所有植物物种相对丰度的矩阵（即样地-物种矩阵）。

##### 变量说明
* `plot_in_year`：采样年份对应的样地ID及处理组信息。所有样地初始均未经过人工干预……