Douglas-fir ring width data for reconstructing past periods of western spruce budworm outbreak
Data files
Oct 20, 2025 version files 688.20 KB
Abstract
The western spruce budworm (Choristoneura occidentalis; "WSB") is one of the most widely distributed native defoliators of coniferous forests in North America, where it plays an important role in shaping ecosystem function. Here we provide tree-ring data used to reconstruct periods of past WSB outbreak at 12 sites across central to northern Colorado over the past 300 years.
https://doi.org/10.5061/dryad.bnzs7h4n3
Description of the data and file structure
Tree ring data for reconstructing past periods of western spruce budworm outbreak across Colorado.
Files and variables
This dataset provides site metadata and annual tree-ring measurements for 15 sites across Colorado where Douglas-fir were sampled to reconstruct periods of past outbreak. Metadata information for all sites are provided in the* Host-Metadata.csv* file. Tree-ring data for each site are provided as individual .rwl files. In each of these data files, the data are stored in Tucson decadal format where the first 10 values following the decade are the 10 annual measurements for the 10 years of that decade. The code 999 or -9999 indicate the end of the record code. Measurements are in units of 0.01 mm (end code 999) or 0.001 mm (end code -9999).
File: Host-Metadata.csv
Description: Metadata for each tree-ring
Variables
- SeriesCode: series code ID - Note: This field matches the corresponding .rwl file. So file B18.rwl has B18 in this column.
- SiteName: name for the site where the data were collected
- Location: US state where the site is located
- latitude: latitude of the site in decimal degrees North
- longitude: longitude of the site in decimal degrees East
- elevation: elevation of the site in meters
- speciescode: 4-letter code of the tree species used - Note codes follow standards established used in the International Tree Ring Databank (available here: https://www.ncei.noaa.gov/pub/data/paleo/templates/tree-species-code.csv)
- species: full species name
- startYear: start year in years CE
- endYear: end year in years CE
- investigators: semicolon separated list of investigators (last, first; last2, first2)
File: WB.rwl
Description: Tree-ring data for the Wild Basin site.
File: TI.rwl
Description: Tree-ring data for the Tree Island Lake Trail site.
File: NI.rwl
Description: Tree-ring data for the North Inlet site.
File: SR.rwl
Description: Tree-ring data for the South Rd. 30 site.
File: SP.rwl
Description: Tree-ring data for the Summerland Park site.
File: WR.rwl
Description: Tree-ring data for the West Rd. 211 site.
File: FP.rwl
Description: Tree-ring data for the Frankenberger Point site.
File: SH.rwl
Description: Tree-ring data for the South Hollowell site.
File: EP.rwl
Description: Tree-ring data for the Estes Park site.
File: SS.rwl
Description: Tree-ring data for the Sugarloaf Saddle site.
File: JP.rwl
Description: Tree-ring data for the Lost Jeep site.
File: WW.rwl
Description: Tree-ring data for the Wigwam I site.
File: B18.rwl
Description: Tree-ring data for the Boulder County 18 site.
File: B19.rwl
Description: Tree-ring data for the Boulder County 19 site.
File: LJ.rwl
Description: Tree-ring data for the Lost Junction site.
File: WSBxClimate-v1.0.5.zip
The Zenodo copy of the most recent version of the Github repository for this project (https://github.com/HARTLabGroup/WSBxClimate/). The project has the following structure:
- .gitignore: a plain text file that specifies intentionally untracked files and directories that Git should ignore
- CITATION.cff: the citation file for this repository
- citationstyle.csl: A Citation Style Language file used to format references in the main text file.
- Code: This subdirectory contains all code written for this project. In order for the code to work, files should be run sequentially (i.e., 01-Data-Download.Rmd then 02-PreprocessingDouglasFir.Rmd ... 06-WSBxClimate-MainText.Rmd). All .R scripts are called internally by .Rmd files. For all R markdown files (.Rmd), the knit version is also included as a Microsoft Word document.
- 01-Data-Download.Rmd: This code will download most of the data.
- 02-PreprocessingDouglasFir.Rmd: This code performs basic preprocessing for the Douglas fir tree-ring series.
- 03-PreprocessingPonderosaPine.Rmd: This code performs basic preprocessing for the ponderosa pine tree-ring series.
- 04-IdentifyControlSites.Rmd: This code identifies the three ponderosa pine chronologies that most closely represent the climate patterns present in the growth patterns of Douglas fir at each site.
- 05-StudyArea.Rmd: This code generates a study area map and characterizes the study area climate.
- 06-WSBxClimate-MainText.Rmd: The code for reproducing the main text and results presented therein.
- k1d.R: Code for performing multivariate event analysis from Gavin (2010).
- references.bib: A BibTeX file containing all information for all references used in the project
- Template.docx: A Microsoft Word document used to a style template for generating the main text file.
- TreeRingfuncs.R: Some supplemental functions for manipulating tree-ring data.
- Documents
- PublishedOutbreakHistory.xlsx - A table containing information on the start and ending of published outbreaks pulled from peer reviewed literature.
- License.md: A license file for the project
- README.md: The repository README.
- WSBxClimate.Rproj: The R project file associated with the project.
Ring-width data for reconstructing periods of WSB outbreak were collected from Douglas fir in the 1990s, but unpublished. Sample sites were selected based on the availability of large, old Douglas fir and the absence of evidence of recent (i.e., since c. 1940) fire or logging to minimize the potential effects of other disturbances on radial growth. At each site, tree-ring data were collected by preferentially sampling at least 20 large Douglas fir using an increment borer. Cores were transferred back to the lab, where they were dried, mounted, and sanded to a fine polish, following standard dendrochronological methods. Ring widths were then measured to a 0.01 mm precision using a Velmex UniSlide digital encoded traversing table paired with a standard light microscope. To ensure accurate dating, ring-width series were visually cross-dated using the maker year approach and statistically verified using the dplR package in R.