DOI: 10.25338/b8s63t
title: Orchard floor plant communities: Multispecies cover crops in commercial almond orchards

description: Cover crops are an important tool for adding biodiversity to agricultural
 systems that are increasingly pressured by climate change and continued
 intensfication. In California, orchard cropping systems are widespread and
 uniquely impacted by drought and uncertain economic conditions. While the
 cash crop is growing in trees, there are significant amounts of land on
 the orchard floor beneath the trees that could be used to support orchard
 sustainability goals. Cover crops could be planted on the orchard floor
 with specific goals such as increasing soil health, increasing soil water
 holding capacity, providing floral resources for pollinators, or many
 other factors. Understanding how planted cover crops interact with
 resident vegetation on the orchard floor is essential for cover crop
 planning and vegetation management. The data here were collected in a
 two-year, three-site experiment in commercial almond orchards in the
 Central Valley of California. Two different five-species cover crop mixes
 were compared to standard orchard floor management practices. Plants were
 surveyed with point-intercept transect surveys seasonally, both within and
 outside of the winter cover crop growing season.
description: The README file has more information about experimental methods
 and information contained in each column of the dataset.
 The two data files contain the same data, but using treatment
 names in the "Treatment" column that match treatment
 descriptions in the associated manuscript. This was updated on 2021-10-26,
 which matches the filename for the dataset with updated treatment
 names.
description: # Orchard floor plant communities: Multispecies cover crops in commercial
 almond orchards Data collected by
 Steven Haring, UC Davis Design and oversight
 by Amélie Gaudin and Brad Hanson ## Description of the data and file
 structure **EXPERIMENT DESCRIPTION:** The data in this dataset come from
 plant community surveys undertaken within a cover cropping experiment that
 took place in commercial almond orchards in Central California, USA from
 2018 to 2020. The experiment was set up at three locations, one each in
 Tehama, Merced, and Kern Counties in California. Each location had four
 repetitions of the experiment at each year, and the experiment was
 repeated at each location (i.e. six site-years total, with two years at
 each of three locations). Each site had two cover crop treatments (i.e.
 pollinator, soil) and one bare ground treatment. The Kern and Merced sites
 also had a more intensive (i.e. all vegetation controlled) treatment. NONE
 in the species column is associated with bare ground. Other values are
 five-character Bayer Codes, which are also known as EPPO Codes. Bayer
 Codes typically use the first three letters of genus and first two letters
 of specific epithet. The Weed Science Society of America maintains a
 Composite List of Weeds, which may be used to verify Bayer codes. In this
 study, the pollinator mix was planted with SINAL, BRSNC, and RAPSR. The
 soil mix was planted with SINAL, RAPSR, VICVI, TRFRE, and SECCE. If these
 cover crop species are found in a plot from a different treatment, they
 are likely to be volunteer plants or resident plants from the existing
 soil seed bank. All other species are considered to be weedy or resident
 vegetation. **DETAILED METHODS:** Data collection was repeated seasonally
 throughout each year of the experiment. Each experimental plot at each
 survey timing was surveyed with 50-meter long point-intercept transects.
 Each plot had a transect across the middle of the plot (i.e. alley) and
 one transect in the tree strip, where cover crops are not planted and
 intensive herbicide programs are applied. Ground cover was identified at
 each of 50 points evenly spaced along each transect (i.e. observations
 within each zone of each plot at each timing should sum to 50). The
 intercepts column shows how many points along the transect were associated
 with the vegetation type identified in the species column. **DATA
 COLUMNS:** * Year: The year in which data were collected the field *
 Month: The month in which data were collected the field * Day: The day in
 which data were collected in the field * ObservationTiming: The relative
 timing (season) in which data were collected. Simpler to use than dates,
 because we were interested in seasonal variation in plant communities *
 Location: The county from which data were collected, corresponding with
 one of our three experimental sites (Kern, Merced, or Tehama Counties in
 California, USA) * Rep: The replicate or block. There were four replicates
 at each site. Replicates were numbered arbitrarily, and replicate IDs
 stayed consistent throughout the experiment * Treatment: The groundcover
 treatment applied to each plot * OrchardZone: The management zone where
 data were collected, either the STRIP at the base of the trees (associated
 with irrigation and higher-intensity management) or the ALLEY between tree
 rows (covering most of the orchard area) * Species: Lists Bayer codes
 (described above) identifying observed plants, or NONE to represent bare
 ground * Intercepts: A count of the number of times a plant species was
 identified along a 50-m-long, 50-point transect