Leather oak (Quercus durata) herbarium leaf N and C stable isotopes and tree ring width index

Increasing anthropogenic emissions of nitrogen (N) and carbon (C) are major threats to ecosystems globally. Although atmospheric N deposition is likely affecting N cycling and community composition in California’s serpentine ecosystems, a historical record of N inputs to vegetation has yet to be reconstructed for these nutrient-limited biodiversity hotspots. For leather oak (Quercus durata var. durata), a foundational, serpentine-endemic species, we investigated leaf N and C isotopic composition (δ15N and δ13C) and leaf %N of herbarium and modern leaf samples collected from 1899 to 2009 from serpentine ecosystems in two study areas in California: Santa Clara County, and Lake and Napa Counties combined. We also evaluated tree ring growth over a similar time period in long-lived leather oak individuals. Leaf δ15N and δ13C values decreased over time in both study areas, likely reflecting changes in the regional atmospheric N and C pools caused by human perturbation.  However, leaf %N value..., , , # Leather oak (Quercus durata) herbarium leaf sample N isotope and tree ring width index

[https://doi.org/10.5061/dryad.mcvdnck6p](https://doi.org/10.5061/dryad.mcvdnck6p)

## Description of the data and file structure

[https://doi.org/10.5061/dryad.mcvdnck6p](https://doi.org/10.5061/dryad.mcvdnck6p)

This file includes a 1) a data set on tree ring widths and ring width index from cores taken at McLaughlin Reserve in Lake County and Coyote Ridge Preserve in Santa Clara County, California; and 2) a set of leaf N and C stable isotope measurements and leaf %N from herbarium and modern samples collected throughout Lake and Napa Counties and Santa Clara County, California.

## Description of the data and file structure

The files has two tabs. Tab one, Leaf Data, includes the leaf data and tab two includes the tree ring data (ring width index). Variables are Date, indicating the date the sample was taken; Accession or ID #, indicating the number associated with the herbarium sample; 15N, i...