Dataset DOI: 10.5061/dryad.6djh9w1f4

Description of the data and file structure

This data set includes plant and soil data collected to understand the role of herds of migratory ungulates and soil conditions in controlling grassland production in Yellowstone National Park. The data span three separate studies: 1988 & 1989, 1999 - 2001, and 2012 - 2014. 

Plant biomass, percent live and dead biomass, graminoid/non-graminoid abundance, and plant chemistry data are nested by site and year. At each site, plant data were collected in replicated (n= 8-12) 0.50 x 0.50 cm quadrats in grazed grassland and in the center 0.50 x 0.50 cm of temporary exclosures (1.5 x 1.5 m) (n = 4 - 6) moved approximately every four weeks during each growing season. At 13 of the study sites, plant data were also collected inside 8 x 8 m, 10 x 10 m, or 15 x 15 m “permanent” exclosures erected the summer before sampling and left in place throughout each study.  During the 1999 -2001 and 2012 – 2014 studies, plant sampling at each site occurred inside the permanent exclosure(s) (ungrazed grassland) usually on the same day and occasionally within three days as in the grazed grassland.  During the 1988 and 1989 study, plant data were collected inside permanent exclosures only at peak biomass.  Soil samples from which carbon and nitrogen were determined were sampled only once in the first year of each of the studies.  Carbon and nitrogen were determined on a sample pooled from three to seven random 0-10 cm soil samples collected in grazed grassland at each site at the beginning of the studies.

            Note that the frequency and/or spatial extent of sampling plant biomass (ie, total biomass, live vs dead biomass, graminoid vs nongraminoid biomass), plant chemistry (nitrogen and phosphorus), and soil chemistry (carbon and nitrogen) differed.  Plant biomass was sampled in grazed grassland and inside temporary and permanent exlcosures at replicated locations at multiple timepoints at each grassland site in each year.  The pooled plant tissue collected at a site provided single measure (ppm) of plant nitrogen and phosphorus for a site at each time point plant chemistry was determined.  Soil chemistry was determined once at each site, providing single measures of soil carbon and nitrogen for each of the sites during each study.  Empty cells in the data file reflect missing data.

Files and variables

File: Data_S1.zip

Description:

• siteid:  Unique identifier for each site.

• lat: Latitude location of site (decimal degrees).

• long: Longitude location of site (decimal degrees).

• elev: Elevation of site (meters).

• year: Year that sample was collected.

• trt: Five codes: gr, te,  pe, sgr, and ste. gr refers to samples collected in grazed grasslands; te refers to samples taken inside temporary exclosures in grasslands, and pe refers to those taken inside permanent exclosures in grasslands.  ste refers to samples of herbaceous vegetation growing under individuals of sagebrush (*Artemisia tridentata) *that had been fenced from grazing with temporary exclosures and sgr refers to samples collected under individuals of sagebrush that had not been protected from grazing. Sagebrush occurred at only two sites, lsg and usg.

• sampleinterval.plt: The sequential intervals during which plants at grazed grassland and shrub-grassland (gr, te, sgr, ste) were sampled during each year.  During these intervals, ungrazed grassland (pe) was sampled mostly on the same day that grazed grassland at a site was sampled.  Refer to “dayofyear.plt” to determine the date that plant samples were collected.

• quadrat#: The identifying quadrat number.

• dayofyear.plt: The day of year that plant biomass was sampled.

• totshtbiom: Shoot biomass (g/m^2) estimated nondestructively with canopy intercept method.

• live.percent: Percent of total biomass that was live (green); estimated as the percent of pin contacts with green tissue.

• dead.percent: Percent of total biomass that was dead (tan, red or brown); estimated as the percent of pin contacts with dead tissue.

• gram.percent: Percent of total biomass that was graminoid (grass, sedge, and rush) biomass.  Calculated as the percent of pin contacts on graminoid tissue.

• forb.percent: Percent of total biomass that was non-graminoid biomass.  Calculated as the percent of pin contacts on non-graminoid tissue.

• shrub.percent: Percent of total biomass that was shrub biomass.  Calculated as the percent of pin contacts on shrub tissue.

• dayofyear.np: Day of year that plant tissue samples were collected for N and P analyses.

• lfnppm: Shoot nitrogen concentration (ppm).

• lfpppm: Shoot phosphorus concentration (ppm).

• soilcppm: Total 0 - 10 cm soil carbon (ppm).

• soilnppm: Total 0 - 10 cm soil nitrogen (ppm).