DOI: 10.17026/ls/3dj5tn
title: Tree-ring growth of S polaris on Svalbard under baseline conditions and artificially enhanced summer rainfall

description: # Data &lt;br&gt;
Tucson format .rwl files (unit = 1/100mm) for three salix polaris tree-ring records from Svalbard. &lt;br&gt;
- Location2_sections.rwl &lt;br&gt;
- Location2_shrublevel.rwl &lt;br&gt;
- Location5_sections.rwl &lt;br&gt;
- Location5_shrublevel.rwl &lt;br&gt;
- reference_Endalen_shrublevel.rwl &lt;br&gt; &lt;br&gt;

Site chronologies derived from tree-ring data &lt;br&gt;
- chronology_loc2_new.csv &lt;br&gt;
- chronology_loc5_new.csv &lt;br&gt;
- chronology_Endalen.csv &lt;br&gt; &lt;br&gt;

each chronology dataset contains: &lt;br&gt; 
- year &lt;br&gt;
- std: standard chronology (detrended using age-dependent spline with 20-year rigidity) &lt;br&gt;
- res: residual chronology (detrended using age-dependent spline with 20-year rigidity and corrected for first-order temporal autocorrelation) &lt;br&gt;
- samp.depth (sample depth, nr of shrubs available for year, set to minimum of 3 years) &lt;br&gt; &lt;br&gt;

# Sites &lt;br&gt;
2 - Adventdalen Polygonal Tundra &lt;br&gt;
78.192°N, 15.862°E &lt;br&gt;&lt;br&gt;

5 - Ny-Alesund terrace along Westbyelva &lt;br&gt;
78.920°N, 11.917°E &lt;br&gt;&lt;br&gt;

Endalen - A riverbed north of Endalselva &lt;br&gt;
78.194°N, 15.793°E &lt;br&gt;&lt;br&gt;

# Experimental Design&lt;br&gt; 
Endalen is a reference site. 15 shrubs were sampled, the dataset contains &lt;br&gt;
shrub-averaged ring widths from 7 of these shrubs &lt;br&gt;&lt;br&gt;

Location 2 and 5 are experimental sites in which some plots were subjected to rainfall additions through irrigation (see sample coding) &lt;br&gt;
"I" plots received enhanced rainfall in 2022 &lt;br&gt;
"ES" and "LS" plots received enhanced rainfall in 2023. &lt;br&gt;
See Magnússon et al. (2024) and associated data for site characterizations, treatment information, plot coordinates and plot environmental conditions &lt;br&gt;
Paper: https://doi.org/10.1016/j.scitotenv.2024.173696 &lt;br&gt;
Data: https://doi.org/10.17026/dans-23v-7hcg &lt;br&gt;&lt;br&gt;

# Sample coding &lt;br&gt;
example shrub level (loc 2 & 5): 2ES3A &lt;br&gt;
example sections (loc 2 & 5): 5LS4BR &lt;br&gt;&lt;br&gt;

These samples codes are built up as follows: &lt;br&gt;
- first digit = location (2 or 5) &lt;br&gt;
- followed by treatment code of one or two digits, where: &lt;br&gt;
 - c = control (no extra rain &lt;br&gt;
 - i = 50mm extra rainfall in late summer 2022 &lt;br&gt;
 - es = 50mm extra rainfall in early summer 2023 &lt;br&gt;
 - ls = 50mm extra rainfall in late summer 2023 &lt;br&gt;
- followed by a value A-I indicating the position within the plot (see Magnússon et al., 2024) &lt;br&gt;
- for section level data, followed by section code (C = collar, R = root, S = belowground shoot) &lt;br&gt;&lt;br&gt;

for the endalen shrublevel samples, the sampled shrubs were simply named S1 - s15. &lt;br&gt;&lt;br&gt;

# Tree-ring measurement &lt;br&gt;
sections averages of root segments (below root collar), root collar (assumed oldest part of shrub, root-shoot transition), belowground shoot and aboveground shoot ('shoot-end') , based on three, sometimes 2 radii per section &lt;br&gt;
sections were averaged per shrub for shrub level datasets (omitting the aboveground shiits due to low number of rings) &lt;br&gt;
Software: LASX 4.13 for sample digitization, Coorecorder 9.0 for tree-ring measuement along radii, CDendro for averaging and crossdating of radii to section level (_sections) and to shrublevel (_shrublevel) &lt;br&gt;
.rwl files can be inspected in notepad &lt;br&gt;&lt;br&gt;

# Scripts &lt;br&gt;&lt;br&gt;

1. script_detrending_chrono.R was used for the following datasets: &lt;br&gt;&lt;br&gt;

- Location2_shrublevel to produce a baseline site chronology (excl. I plots from 2022 onwards and ES and LS plots from 2023 onwards) &lt;br&gt;
- Location2_sections to produce section level RWI &lt;br&gt;
- Location2_shrublevel to produce shrub level RWI &lt;br&gt;&lt;br&gt;

- Location5_shrublevel to produce a baseline site chronology (excl. I plots from 2022 onwards and ES and LS plots from 2023 onwards) &lt;br&gt;
- Location5_sections to produce section level RWI &lt;br&gt;
- Location5_shrublevel to produce shrub level RWI &lt;br&gt;&lt;br&gt;

- reference_Endalen_shrublevel to produce a baseline site chronology &lt;br&gt;&lt;br&gt;

this script also produced the chronology plots and chronolgy tables &lt;br&gt;&lt;br&gt;

2. script_climgrowth was applied to all three chronologies for a stand ard minimum available time period from 2003 onwards &lt;br&gt;
this script produced the climate-growth bar plots &lt;br&gt;&lt;br&gt;

3. script_treatment was used on section- and shrub-level detrended RWI data for locations 2 and 5. &lt;br&gt;
this script produced the mixed modelling and posthoc tables and treatment effect bar & jitter plots &lt;br&gt;
description: LAS X, 4.13
description: CooRecorder, 9.0
description: CDendro, 9.0
description: R, 4.1