Regional differences in soil stable isotopes and vibrational features at depth in three California Grasslands

There is an urgent need to investigate soil carbon dynamics in grasslands in differing precipitation and temperature regimes in light of current and future climate change. In this study, we assessed differences in soil stability, turnover, and organic matter composition along a climatic gradient of California grasslands. We focused on organic matter composition across three California grassland sites, from a dry (~300 mm precipitation/year) and hot regime (MAT: 14.6 ) to a wet (~2160 mm precipitation/year) and cool (MAT: 11.7 ) regime. We determined changes in total elemental and stable isotopic concentrations of soil carbon, nitrogen, δ13C, δ15N, and vibrational features as measured through Diffuse Reflectance Infrared Fourier Transformed Spectroscopy (DRIFTS) to 1m soil depth. We measured two isotopic indicators of soil turnover and stability, a natural carbon isotope approach defined as beta ( ), and the relationship between δ15N and C:N values. We did observe significantly more carb..., Study Area 
Soil samples were collected at three annual grasslands: Sedgwick National Reserve (Suttle et al., 2007), University of California Hopland Research and Extension Center and the Angelo Coast Range Reserve in California (fig.1). All three sites are dominated by exotic annual grasses , while forbs are of both native and exotic origin. The dominant vegetation at Angelo is a mix of Aira spp., Bromus spp, and Briza spp. (Foley et al., 2023). At Hopland, it is a mix of Avena spp., Bromus spp., Erodium spp., and Festuca spp. (Foley et al., 2023). At Sedgwick, the dominant vegetation is Avena spp. and Bromus spp. (Foley et al., 2023). At Angelo, soils are part of the Holohan-Hollowtree-Casabonne Complex, are classified as Ultic Haploxeralfs. The parent material is largely gray wacke and mudstone. At Hopland, soils are part of the Yorkville series, and are classified as Typic Argixerolls. Parent material is largely sandstone and shale. Soils at Sedgwick are part of the Salinas series a..., The only programs are Excel and R (though R is only used to process/clean/plot the data, all of this can be done in Excel). , # Organic Matter Dynamics at Depth Across a Precipitation Gradient of California Grasslands

There are 4 xlsx files associated with this dataset:

-Sample_Metadata_Precipitation_Grad gives associated metadata with each sample ID. This metadata includes the location where it was sampled, the replicate, the depth, and so on.

\- Precipitation_gradient_iso_data gives all the isotopic and elemental data assocaited with each sample ID. NAs refer to missing or lacking data. This data sheet represents data that comes out of the Stable Isotope Ecosystem Laboratory at UC Merced, with metadata attached for each sample. The measurements included in this datasheet make (C% and N%) make it possible to calculate carbon stocks, an important bulk density corrected factor, for each site. Measurements of stable isotopes (d13C and d15N) were also important markers of decomposition and turnover for the sites we were analyzing.

-Precip_grad_C_inventories gives all the necessary data to calculate carbon sto...