Leather oak (Quercus durata) herbarium leaf N and C stable isotopes and tree ring width index
Data files
Jan 09, 2025 version files 27.16 KB
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Data_File2.xlsx
24.39 KB
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README.md
2.78 KB
Abstract
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 values and stem growth did not change directionally over time, indicating that increasing atmospheric N deposition and CO2 concentration may not translate to increased N uptake or productivity in plants with conservative growth strategies, even in ecosystems thought to be N-limited. In serpentine systems, this could competitively advantage nitrophilic invasive annual grasses and accelerate trends toward native species loss. While the rates of decline in leaf δ15N values were similar between study areas, rates of decline in leaf δ13C values were steeper in Santa Clara County, possibly reflecting its more urban environment. Herbarium samples combined with tree ring data can provide a valuable opportunity to explore the historical record of human-induced changes in N and C cycling and their biotic impacts.
README: Leather oak (Quercus durata) herbarium leaf sample N isotope and tree ring width index
https://doi.org/10.5061/dryad.mcvdnck6p
Description of the data and file structure
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, indicating the delta 15N value of the leaf; %N, indicating the percent N of the leaf; 13C, indicating the delta 13C value of the leaf, and location, indicating the county in which the sample was collected. The Accession or ID # includes an abbreviation for the herbarium (CAS=California Academy of Sciences, UC=University of California). For modern samples, the Accession or ID # column includes an independent identifier number, date = collection date. Tab two, RWI data, includes County, indicating the county where the core sample was collected; Years, indicating the years covered by the core sample. Columns C-W represent the individual tree cores, where T(#) identifies the tree from which the core was taken, and RWI refers to the averaged calculated ring width index for the time period indicated.
Files and variables
File: Data_File.xlsx
Description: Tab 1 Leaf data
Variables
Date, indicating the date the sample was taken
Accession or ID #, indicating the number associated with the herbarium sample. The Accession or ID # includes an abbreviation for the herbarium (CAS=California Academy of Sciences, UC=University of California).
15N, indicating the delta 15N value of the leaf
%N, indicating the percent N of the leaf
13C, indicating the delta 13C value of the leaf
Location, indicating the county in which the sample was collected.
Description: Tab 2 RWI data
Variables
County, indicating the county where the core sample was collected
Years, indicating the years covered by the core sample
Columns C-W represent the individual tree cores, where T(#) identifies the tree from which the core was taken, and RWI refers to the averaged calculated ring width index for the time period indicated
Code/software
excel