Spatiotemporal patterns of rising annual plant abundance in grasslands of the Willamette Valley, Oregon (USA)

Context: Plant communities are undergoing compositional changes that affect ecosystem function. These changes are not always uniform across the landscape due to heterogenous topographic and edaphic conditions. To predict areas most at risk of change, it is necessary to identify the landscape drivers affecting plant abundance.
Objectives: Annual plants are increasing across the Wwestern USA, largely driven by non-native annual invasions. Here, we quantified change in annual plant abundance and identified landscape factors contributing to that change over the past 35 years.
Methods: We focused on Willamette Valley (Oregon) grasslands because they represent a new example in this phenomenon. To understand the spatiotemporal patterns of annual plant abundances between 1986 and 2020, we combined a remote-sensing vegetation cover dataset from the rangeland analysis platform with gridded soils data and topographic variables. We determined the rate of change in percent cover for e..., df_RAP.csv: Yearly (1986-2020) vegetation cover data of annual and perennial forbs and grasses for the Willamette Valley were downloaded as TIFF files (30-m resolution) from the Rangeland Analysis Platform's Google Earth Engine catalog. To eliminate forested and other non-grassland areas, we masked RAP data to grassland/herbaceous, pasture/hay, and shrub/scrub classifications in the National Land Cover Database 2019 Land Cover dataset using the raster package in R. Prior to this, we had previously resampled the land cover dataset from 10-m to 30-m resolution and reprojected to WGS 1984 using ArcMap 10.5. For each year in the 1986-2020 RAP dataset, we calculated new rasters for total herbaceous cover by summing the annual and perennial layers. We then filtered to cells with ≥20% average total herbaceous cover across the 35 years to avoid areas which may have skewed estimates due to low herbaceous cover in general (e.g., grassland borders near forests). Finally, we filtered to the 16 site..., , , # Data from: Spatiotemporal patterns of rising annual plant abundance in grasslands of the Willamette Valley, Oregon (USA)

This README file from: Spatiotemporal patterns of rising annual plant abundance in grasslands of the western Pacific Northwest, USA, was generated on 2022-07-06 by Paul B. Reed

#### GENERAL INFORMATION

1. Title of Dataset: Data from: Spatiotemporal patterns of rising annual plant abundance in grasslands of the western Pacific Northwest, USA
2. Author Information
A. Principal Investigator Contact Information
Name: Paul B. Reed
Institution: Institute for Applied Ecology
Address: 4950 SW Hout St
Corvallis, OR 97333
Email: [[e-mail]](mailto:[e-mail])
3. Date of data collection: 2022-02-01
4. Geographic location of data collection: Willamette Valley, Oregon, USA
5. Information about funding sources that supported the collection of the data:
USDA-NIFA postdoctoral fellowship award # 2021-67034-35136

#### SHARING/ACCES...

### 研究背景
植物群落正发生组成结构变化，进而影响生态系统功能。受地形与土壤异质性条件影响，这类变化在整个景观尺度上并非均匀一致。若要预测最易发生变化的区域，需明确调控植物丰度的景观驱动因子。

### 研究目标
美国西部的一年生植物丰度正持续上升，这一现象主要由外来一年生植物入侵所驱动。本研究量化了过去35年间一年生植物丰度的变化情况，并明确了驱动该变化的景观因子。

### 研究方法
本研究聚焦美国俄勒冈州威拉米特河谷的草原，因其为该现象的新研究案例。为解析1986年至2020年间一年生植物丰度的时空分布格局，我们将牧场分析平台（RAP, Rangeland Analysis Platform）的遥感植被覆盖数据集，与网格化土壤数据及地形变量相结合。
关于df_RAP.csv数据集：我们从RAP的谷歌地球引擎（GEE, Google Earth Engine）目录中下载了1986-2020年威拉米特河谷一年生与多年生草本、禾草的年度植被覆盖数据，格式为TIFF文件（分辨率30米）。
为剔除森林及其他非草原区域，我们使用R语言的raster包，基于美国国家土地覆盖数据库2019版（NLCD 2019, National Land Cover Database 2019）中的草原/草本、牧场/干草、灌丛/灌木分类，对RAP数据进行掩膜处理。在此之前，我们已通过ArcMap 10.5将土地覆盖数据集从10米分辨率重采样至30米，并转换至世界大地测量系统1984（WGS 1984）坐标系。
针对1986-2020年RAP数据集的每一年，我们通过累加一年生与多年生图层，计算得到总草本覆盖的新栅格数据。随后我们筛选出35年间平均总草本盖度≥20%的栅格单元，以避免因整体草本盖度较低（例如林缘草地）导致的估计偏差。最终我们筛选得到16个研究站点……

### 数据集来源
本数据集关联研究：《美国俄勒冈州威拉米特河谷草原一年生植物丰度上升的时空格局》
本README文件生成于2022年7月6日，作者为Paul B. Reed

#### 基本信息
1. 数据集标题：《美国太平洋西北西部草原一年生植物丰度上升的时空格局相关数据集》
2. 作者信息
A. 首席研究员联系方式
姓名：Paul B. Reed
所属机构：应用生态研究所（Institute for Applied Ecology）
地址：4950 SW Hout St, 科瓦利斯, 俄勒冈州 97333
邮箱：[e-mail]
3. 数据收集日期：2022年2月1日
4. 数据采集地理区域：美国俄勒冈州威拉米特河谷
5. 数据收集资助来源：美国农业部国家食品与农业研究所（USDA-NIFA）博士后奖学金，项目编号：2021-67034-35136

#### 共享/获取……