https://doi.org/10.5061/dryad.rjdfn2zf6

Authors: Andrew Kaul and Brian Wilsey

Affiliation: Iowa State University

Journal: Oecologia

This README provides a brief description of the files associated with this project and for each file, we provide a description of each column variable. This archive contains three data files:

“cc_community_data” – this excel file contains the plot-level measurements of plant community composition in all sampled plots in this study. This data is transcribed from the raw data, recorded on archival notebooks. Each numbered column represents a species. Each row represents a quadrat in a plot in a sample date.

“cc_species” – this excel file contains data on the attributes of each species sampled, including taxonomy, nativity, duration, and functional group membership.

“Cover Crop Function Measures” this excel file contains data on plot-level characteristics of the plant community, sampled in May and July of 2018. Data include measurements of canopy height measured with a Robel pole, and measures of try biomass averaged from 2 0.1m2 clip plots.  

Description of the data and file structure

“cc_community_data” – description of column variables

• Treat
  • Numeral abbreviation for experimental treatment corresponding to which species were added as cover crops.
  • Numbers for each treatment are as follows
    • 1 – Control
    • 2 – Oats (Avena sativa)
    • 3 – Radish (Raphanus satvus)
    • 4 – Oats & Radish
    • 5 – Wild Rye (Elymus Canadensis)
    • 6 – Primrose (Oenothera biennis)
    • 7 – Wild Rye & Primrose
    • 8 – DOT mix
      • These plots are removed from all analyses.
• Sample: Integers 1-5, corresponds to each sample date.
• Plot: Integers 1-80, corresponds to each experimental plot.
• quadrat: Integers 1-2, identifier for each quadrat (0.1 square meters) sampled within each experimental plot and sample date. Quadrats serve as sub-samples and average values were calculated for each species in each plot prior to analyses.
• Columns C – DK: Each column is a unique taxon. The Latin names and other corresponding information for each of these 6-letter codes can be found in the file “cc_species”. Values indicate the abundance of each species in the corresponding quadrat as indicated by the "sample", "plot", and "quadrat" columns. Values for abundance of each species are in units of "hits" or "touches" using point sampling at each of the four corners of the quadrat. Each cell contains the summed number of hits on a pin placed at each of the four corners of the quadrat. If a species was present within the quadrat, but did not touch any of the four pin drops, then it was assigned a value of 0.5 or a half of a hit. See published manuscript methods for further details.

“cc_species” – description of column variables

• Family: Description – taxonomic family designation
• Common: Description – a common name often used for each species, when applicable. This column was not used for any analysis.
• Genus: Description – taxonomic Genus designation
• Epithet: Description – specific epithet
• Taxon: Description – up to 6 letter abbreviation of each species’ name, generally using the structure of first 3 letters of the genus, then the first three letters of the specific epithet. For unknown species, a unique series of 1-6 letters was generated for each species. This corresponds to the column “sascode” in other files.
• Seeded: Description – y = yes, n = no, cc = cover crop species. Species not seeded recruited as volunteers. Cover crops were removed from community level response analyses.
• Nativity: Description – native or exotic. Exotic species are not native to the study region. Taxa not identified to species level are labeled as “unknown” for nativity
• Duration: Description – description of life history. Factor with levels - annual, biennial, perennial, woody, unknown
• Fg: Description – abbreviation for “functional group”. Factor with levels – c3_annual, c4_annual, perennial_forb, woody, c3_perennial_grass, and c4_perennial_grass. “c3” and “c4” describes photosynthetic pathway.

“Cover Crop Function Measures” – description of column variables

• Plot (col A)
  • Integers 1-80 correspond to each of the experimental treatment plots.
  • 10 of these plots were not included in the final analysis because they had a treatment of interest to the grand funder, that is not relevant to this manuscript
• Treat (col B): Experimental treatment. This specifies which species were sown as cover crops. Control plots received no cover crop. The treat “DOT” was a cover crop mixture of three species that the Iowa Department of Transportation (DOT) use in some revegetation projects. Those plots were excluded for all analyses in this manuscript.
• Thistle (col C): Dried biomass (g) of Cirsium arvense, Canada thistle
• Dandelion (col D): Dried biomass (g) of Taraxacum officinale, dandelion
• Other biomass (col E): All dried biomass (g) other than thistle and dandelion
• Total biomass (col F): Thistle + dandelion + other biomass
• Thistle (col G): Dried Canada thistle biomass from the second sample in 2018 (July)
• Grass & forb (col H): All other biomass from the second sample in July
• Total biomass (col I): Cols G + H
• Col J: Difference between the total biomass measures in 2018 (late – early)
• Mean canopy height (col K): Mean (between 2 estimates) canopy height (cm) based on visual assessment using a Robel pole in May 2018. This is an estimate of the highest visible point not fully obstructed viewed from a 1m height at 3 m distance.
• Mean canopy height (col L): A second estimate of canopy height from July 2018
• Mean canopy growth (col M): Col L – col K