Dataset DOI: 10.5061/dryad.bvq83bkq0

Description of the data and file structure

We compiled a dataset of intra-annual, cellular-level conifer wood (xylogenesis) formation observations—GloboXylo. This dataset comprises weekly to biweekly observations from tree stems over the course of at least one growing season. In this study, we use ~ 144 000 cell count observations from 2559 tree × years, collected across 1273 trees between 1998 and 2021. This period reflects the availability of observations rather than a posterior selection. Our dataset covers mostly dominant and co-dominant trees from 27 conifer species. Spruces represented close to half of all observations (three Picea spp, P. mariana + P. abies + P. obovata, 1234 tree × years), followed by pines (12 Pinus spp, 584 tree × years) and larches (three Larix spp, 387 tree × years). These observations are distributed across 105 sites spanning Europe, North and South America, and Asia, and represent a wide climatic space, from boreal to semi-arid forests.

Files and variables

Scripts

• 0_Load_data.R: Loads all data files, defines common variables and factors, and performs initial data formatting used by all subsequent analyses.

• 1_Maps.R: Generates maps showing the geographic distribution of study sites and associated climatic context.

• 2_Cross-biome_variability.R: Quantifies and visualizes variability in growth metrics across climate zones and biomes.

• 3_Relative_importance.R: Assesses the relative importance of growing season length, growth rate using statistical models.

• 4_Model_effect_of_climate.R: Fits and evaluates models describing the effects of climatic variables on growing season length, growth rate, and resulting total annual growth.

All data files are provided in CSV format and are located in the Data/ directory.

'NA' values in the tables stand for 'Not Available'.

clim.csv

Description:
This file contains long-term climate descriptors for each study site, including temperature, precipitation, growing season metrics, and climate classification.

Key variables:

• Site: Site identifier
• MAT: Mean annual temperature (°C)
• MAP: Mean annual precipitation (mm)
• MAVPD: Mean annual vapor pressure deficit (kPa)
• MAR: Mean annual radiation (MJ m⁻² yr⁻¹)
• MAPET: Mean annual potential evapotranspiration (mm)
• AI: Aridity index
• GST: Mean growing season temperature (°C)
• GSP: Growing season precipitation (mm)
• GSVPD: Growing season vapor pressure deficit (kPa)
• GSR: Growing season radiation
• GSPET: Growing season potential evapotranspiration (mm)
• Koppen: Köppen–Geiger climate classification
• Climate_zone: Biome category (e.g. Temperate, Continental)

globoxylo.csv

Description:
This file contains individual tree measurements used to quantify growth dynamics and xylogenesis across species, sites, and years.

Key variables:

• Site: Site identifier
• Species: Tree species
• Tree: Tree identifier
• Year: Observation year
• RCN: Radial cell number at the end of the growing season
• bE: Onset of cell enlargement (DOY)
• cE: Cessation of cell enlargement (DOY)
• dE: Duration of cell enlargement (days)
• tip: Timing of peak cell production (DOY)
• r90: average rate of cell production at which 90% of annual growth is achieved (cells day-1)

met_year.csv

Description:
This file contains yearly climate data and derived anomalies for each site, used to relate interannual climatic variability to growth responses.

Key variables:

• Site: Site identifier
• Year: Calendar year
• Tmin, Tmax, Tmean: minimum, maximum, and mean temperature (°C)
• Rs: Solar radiation
• VPD: Vapor pressure deficit (kPa)
• P: Precipitation (mm)
• PET: Potential evapotranspiration (mm)
• PPET: Precipitation minus PET (mm)
• SPEI3, SPEI6, SPEI12: Standardized Precipitation–Evapotranspiration Index at 3-, 6-, and 12-month scales
• GDD: Growing degree days (°C days)

Climatic variables with no suffix indicate yearly averages.

Variables with suffixes (e.g., _djf) are 3-month seasonal averages for the corresponding metric.

• _djf: winter, which is defined as December–January–February, in the Northern Hemisphere
• _mam: spring, March-April-May
• _jja: summer, June-July-August
• _son: autumn, September-October-November

site_metadata.csv

Description:
This file provides geographical metadata and contributor information for each study site included in the analysis. This file is used to link site-level climatic data with tree- and year-level observations.

Variables:

• PI: Name of the site Principal Investigator
• Site: Short site identifier used across all datasets
• Site_name: Full site name
• Longitude: Longitude (decimal degrees)
• Latitude: Latitude (decimal degrees)
• Elevation: Elevation above sea level (m)
• Years: Years during which data were collected at the site

site_pis.csv

Description:
This file provides full contact information of the Principal Investigator corresponding to each site.

Variables:

• Site: Site identifier
• PI: Name of the site Principal Investigator
• Mail: Email to contact PI at the time of manuscript publication
• Affiliation 1: Principal affiliation of PI at the time of manuscript publication
• Affiliation 2: Secondary affiliation of PI at the time of manuscript publication

site_summary.csv 

Description:
Overview of study sites by combining contributor information, sampling effort, species composition, site location, and key climatic descriptors. This file is used for mapping purposes.

Variables:

• PI: Name of the Principal Investigator
• Group: group of site identifier (individual sites have been grouped for mapping)
• Site_name: Full site name
• Years: Years during which samples were collected at the site
• n: number of sampled trees × years
• Species: number of species present
• Longitude: Longitude (decimal degrees)
• Latitude: Latitude (decimal degrees)
• Elevation: Elevation above sea level (m)
• MAP: mean annual precipitation (mm)
• MAT: mean annual temperature (°C)
• AI: aridity index
• Climate_zone: Biome category
• Koppen: Köppen–Geiger climate classification

soil.csv

Description:
This file contains soil descriptors as obtained from the SoilGrids dataset.

Variables:

• Site: Site identifier
• bdod_0-5cm: Soil bulk density from 0 to 5 cm deep
• bdod_5-15cm: Soil bulk density from 5 to 15 cm deep
• cec_0-5cm: Cation exchange capacity at ph 7 (mmol(c)/kg) from 0 to 5 cm deep
• cec_5-15cm: Cation exchange capacity at ph 7 (mmol(c)/kg) from 5 to 15 cm deep
• clay_0-5cm: Soil clay content (g/kg) from 0 to 5 cm deep
• clay_5-15cm: Soil clay content (g/kg)  from 5 to 15 cm deep
• nitrogen_0-5cm: Soil nitrogen content (cg/kg) from 0 to 5 cm deep
• nitrogen_5-15cm: Soil nitrogen content (cg/kg) from 5 to 15 cm deep
• phh2o_0-5cm: Water pH (pH*10) from 0 to 5 cm deep
• phh2o_5-15cm: Water pH (pH*10) from 5 to 15 cm deep
• soc_0-5cm: Soil organic carbon (t/ha) from 0 to 5 cm deep

soc_5-15cm: Soil organic carbon (t/ha) from 5 to 15 cm deep

tree_metadata.csv 

Description:
Descriptive information for each sampled tree used in the analyses.

Variables:

• Site: site identifier
• Tree: tree code
• Species: species
• Class: social or canopy class
• Age: estimated tree age (years)
• Diameter: stem diameter (cm)
• Height: tree height (m)
• Year: the year of measurement

Additional fields include remarks on tree condition or sampling (Remark), internal coding information (Code).

Code/software

Software requirements

All analyses were conducted using R version 4.3.2.

No platform-specific dependencies are required.

Code structure and reproducibility

All R scripts are located in the Scripts/ directory.
Each script is self-contained but requires sourcing the file:

• 0 Load data.R

Before running the scripts, the working directory must be set to the root folder containing both the Scripts/ and Data/directories.

Scripts are intended to be run sequentially, from 0 to 4.
Running the full sequence will:

• reproduce all figures presented in the manuscript
• reproduce most statistical analyses reported in the text

Total runtime is < 10 minutes on a standard desktop computer.

Access information

Climatic data were derived from the following sources:

• https://www.climatologylab.org/terraclimate.html