XyloDensMap: a georeferenced dataset for the wood density of 110,000 trees from 156 European species in France
The XyloDensMap collaboration has assembled a dataset of 110,763 individual tree records of wood density from 156 species, across a broad range of ecological conditions in France, reflecting a large set of European climates. Data include the measurement of the average anhydrous wood density (mass of dry wood divided by the dry volume) and an estimate of the basic wood density (mass of dry wood divided by the green volume, estimated using volumetric shrinkage coefficients gathered from a literature review) of radial wood cores extracted from tree stem at a conventional breast height on 20,697 forest plots of the French National Forest Inventory (NFI). Additional information on stand’s geographical position, climatic conditions, tree age, height and circumference at stem breast height are provided. Further, wood shrinkage has been measured around one spatially systematic fraction (1/4th) of the collected cores, providing data for further refined modelling of this shrinkage, in addition to reference values available in the literature.
The dataset is composed of three comma-separated files, one R code, and one metadata file.
- The first file (xdm_individual_density_data.csv) provides tree- or stand-level information for each of the 110,763 increment cores, along with the corresponding mean anhydrous wood density (WD0), weighted mean anhydrous wood density (WD0w), mean basic wood density (WDb), weighted mean basic wood density (WDbw) and the wood volumetric shrinkage (WS) used to convert anhydrous into basic wood density. Missing values are denoted by NA.
- The second file (xdm_species_density_data.csv) provides statistics at species level for the mean weighted basic wood density (WDbw).
- The third file (xdm_individual_shrinkage_data.csv) provides the wood volumetric shrinkage measured on a subset of 23,828 wood cores. These values can be used as an alternative to the default literature shrinkage values used to estimate the basic wood density, either by estimating volumetric shrinkage means by tree species (see example in the fourth file), or by a more sophisticated modelling approach taking into account individual tree or core attributes.
- The fourth file (xdm_R_import_and_manipulate_data.R) is an R code designed to guide the user through data import and manipulation, with examples of data operations and visualizations, a theoretical example of biomass calculation using the species wood density means provided in the second file, and an example of recalculation of the basic wood density using the shrinkage values contained in the third file instead of the shrinkage values of the literature.
- The fifth file (xdm_metadata.txt) is a metadata file containing all definitions and units for each table and each variable.