Data publication: Plant data of the Horizon 2020 project NEXT

Plant‑Soil Chemistry Dataset (Raja 2019 Field Campaign)

## 1. Overview  

This repository contains the **final, cleaned chemistry data** that were produced from the 2019 Raja field campaign.  <br>
The data combine:

* Plant tissue concentrations (leaf, bark, needles, …) for a set of selected elements.  <br>
* Corresponding soil‑till depth, point location, lithology and basic tree information.  <br>
* Element‑specific relative‑standard‑deviation (RSD) uncertainties that were calculated from laboratory‑derived uncertainty parameters.

All files are provided in **CSV** format (UTF‑8, `,` separator) and/or the R programming language binary format RData.

*The exact set of tissue files depends on the species/plant‑parts that were sampled; the naming convention is `pl` + lower‑case abbreviation of the tissue (generated by `abbreviate(Plant, minlength = 2)` + `PlantPart`).*

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## 2. Column description (common to all tables)

| Column | Meaning | Type |<br>
|--------|---------|------|<br>
| `PointID` | Unique identifier for the sampling point (e.g., `NEXT‑2019‑257`). | character |<br>
| `X` / `Y` | Projected coordinates (Easting / Northing, EPSG 3067). | numeric |<br>
| `Plant` | Species name (full). | character |<br>
| `PlantPart` | Plant part sampled (`Leaf`, `Bark`, `Fruit`, …). | character |<br>
| `Tissue` | Short code: `&lt;abbr&gt; &lt;PlantPart&gt;` (e.g., `Ac Leaf`). | character |<br>
| `Lithology_updated_Sol` | Detailed lithology description from field notes. | character |<br>
| `Lith_simpl` | Simplified lithology (e.g., `Mafic rocks`). | character |<br>
| `TillDepth_cm` | Soil till depth at the point (cm). | numeric |<br>
| **Element columns** (e.g. `Al`, `As`, `Ca`, …) | Measured concentration **or** relative uncertainty, depending on the file (see below). | numeric |<br>
| `Tissue` (re‑appears) | Same as above – kept for convenience. | character |

### 2.1. Concentration vs. Uncertainty tables  

* **`Plant_all_final.csv`** – contains **concentrations** (units as reported by the laboratory, typically mg kg⁻¹).  <br>
* **`Plant_uncensored_raw.RData`** – contains the very original, untreated data.  <br>
* **`*_uncertainty*.csv`**  – the element columns have been **replaced by their relative standard deviation (RSD)**, i.e. a unit‑less proportion (`0.12` = 12 % RSD).  

If you need both concentration **and** uncertainty for a given point, use the two files together (join on `PointID`).

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## 3. Usage notes  

* **Joining concentration &amp; uncertainty** – the two CSVs 'plant' and 'plant_uncertainty' share the same column order and can be merged on `PointID`.  <br>
* **Missing values** – `NA` indicates either a non‑detected element or that no uncertainty parameter was available for that element.  <br>
* **Spatial reference** – coordinates are in **ETRS89 / Lantmäteriet 3006 (EPSG 3067)**, suitable for Swedish national mapping.  <br>
* **Element selection** – in the subdatasets not every element is present in every tissue file; only the elements that passed the QC selection criteria are kept.