DOI: 10.5061/dryad.n8pk0p2rx
title: Plant communities, grazing intensity, soil properties and decomposers in grasslands across elevation in the Eastern Carpathians in Ukraine

description: This data set contains information on plant community properties, grazing
 intensity, elevation, soil properties and density of soil decomposers
 collected in 2006 and 2007 from the 31 semi-natural grasslands exposed to
 cattle grazing along elevation gradient at large topographic scale ranging
 from the Carpathian Mountains, across the adjacent foothills to the plain
 areas. Plant community properties are represented by the following
 variables for each of the 31 study grassland: number of species (species
 number 100 m-2), number of functional groups 100
 m-2 (that is, legumes, grasses, rushes and sedges, and non-legume
 forbs), proportion of undesirable weeds (%), number of
 species of legumes (species number 100 m-2), number of species of
 grasses (species number 100 m-2), number of species of rushes and
 sedges (species number 100 m-2), and number of non-legume forbs
 (species number 100 m-2). Grazing intensity is measured
 as cattle density (livestock units h-1). Soil properties
 are represented for each 31 study grassland by bare soil exposure
 (%) , soil organic carbon content (%), and soil pH. Density of
 soil decomposers are represented by biomass of
 earthworms g m-2 and abundance of soil
 microorganisms cells × 108  g (dry
 soil)-1. Plant community composition is based on individual
 species’ canopy cover. This dataset also contain information on the
 following plant traits for each plant species (n=175 species) found across
 the 31 study pastures across 2006 and 2007 sampling years: family
 of the plant species, belonging to
 legumes, grasses, rushes and sedges, non-legume
 forbs, and undesirable weeds. All data are averages
 across the two sampling years. 
description: Study area
 and site selection We studied 31
 semi-natural grasslands (in 2006 and 2007), that have been used for
 decades as public pastures for cattle grazing. The study grasslands are
 distributed throughout the Chernivtsi Region (47°43' <i>–
 </i>48°41' N × 24°55' – 27°30' E)
 located in the south-west of Ukraine along the rivers Dniester, Prut and
 Siret.  Of the 31
 grasslands sites, 12 were selected within the plains, 12 within the
 foothills and 7 within the mountains. All grasslands have been used as
 common grazing lands for cattle pasturing by private households, which
 typically have 2-3 livestock units per household. Grazing season depends
 on the growing season of
 vegetation and varies for the three physical-geographical
 zones. The grazing season for mountain grasslands lasts nearly 120-150
 days, for the foothills around 180 days and for the plains zone 210-220
 days. Sampling was
 performed identically for each of the compared ecosystems during June–July
 in 2006 and 2007. The same grassland sites were sampled twice, i.e. one
 time per year. A handheld GPS-12 Garmin<sup>®</sup> was used
 to identify the geographic coordinates and average elevation (m asl) for
 each study ecosystem. Four plots (10 m × 10 m) were selected within each
 of the 31 grassland sites. Placement of plots was random but constrained
 by the edges and size of the field site. The average closest distance
 between two neighboring plots was 10 m and was chosen to minimize the
 potential for spatial autocorrelation influencing the results. The
 distance from plot to the edges of the grassland was 10 m to prevent edge
 effects. Within each plot, a transect was positioned diagonally through
 the plot. Three 1 m by 1 m subplots for estimation of bare soil, and
 earthworm sampling were randomly selected along the transect with a
 minimum distance to the next subplot of 1 m. Soil samples for microbial
 and chemical analysis were taken from one of the three subplots within
 each plot. Locations of plots and subplots within each grassland site
 differed across the two years. Cattle density and bare
 soil exposure Cattle density was measured as
 the number of livestock units per hectare of grassland area (livestock
 units h<sup>-1</sup>). For this, the number, type and age of
 cattle were recorded for private households, which used the pastures
 during the grazing seasons of the two study years. We transformed the
 number of cattle to livestock units based on the widely used conversion
 factors for Europe, as follows: 1 for dairy cows, and males (2 years old
 and over);  0.8 for other cows (2 years old and over), including cows that
 have not yet calved (heifers); 0.7 for animals from 1 to 2 years old; and
 0.4 for animals under 1 year old. We used this cattle density measure as a
 proxy for the degree of grazing intensity of the study pastures. For each
 1 m² subplot, the fraction of bare soil was visually estimated. The mean
 of the three subplots and then the four plots was taken to approximate the
 percent bare soil per grassland in each year. Cattle density and the
 fraction of bare soil were averaged across the two sampling
 years. Vegetation
      
  Vegetation was recorded within each plot during the peak growing season
 for the different physical-geographical zones (June–July) in the two study
 years. All plant species were determined within each plot. We used the
 number of species as a measure of plant species richness 100
 m<sup>-2</sup>. Within each plot three 1 m × 1 m randomly
 selected subplots were used to estimate the relative cover of each species
 by vertically projecting canopy cover (%) for each species within each
 subplot. Averages were then taken across the three replicate subplots. All
 recorded species were classified into four functional groups: legumes
 (Fabaceae), grasses (Poaceae), other monocots (rushes and sedges), and
 forbs (other than legumes). The number of functional groups was used as
 the measure of plant functional diversity per 100
 m<sup>2</sup>. Further, species were classified as undesirable
 weeds if they were known to reduce grazing efficiency, forage yield,
 palatability and quality, therefore contributing to lower forage and
 animal production of grassland ecosystems. The number of undesirable weed
 species was quantified on the 100 m<sup>2</sup> plots. Data on
 plant species richness, functional diversity and richness of undesirable
 weeds were averaged across the four plots level for each year and further
 averaged across the two sampling years. Further, we measured the
 proportion of undesirable weeds as the ratio of the species number of the
 undesirable weeds to the total plant species number. Data on canopy cover
 (%) for each species were averaged across the four plots within each year
 and scaled to unitless relative cover measures (C) ranging from 1 to 5 in
 accordance with Braun-Blanquet: C = 1 for cover from 1 to 5 %; C = 2 for
 cover from &gt;5 to 25 %; C = 3 for cover from &gt;25 to 50 %; C =
 4 for cover from &gt;50 to 75 %; C = 5 for cover &gt;75%. Further,
 the relative cover measures for each species were averaged across the two
 sampling years. Soil sampling and
 analysis Before soil
 sampling, vegetation and upper litter layer were removed in a small area.
 One soil sample per plot (for a total of four samples per grassland) was
 collected at 0−10 cm depth during the vegetation sampling campaign within
 each of the grassland sites using a soil corer with a diameter of 5 cm.
 The soil samples were immediately stored at -5 <sup>o</sup>C
 for microbial and chemical analysis. For the examination of organic carbon
 content and soil pH analysis the soil samples were air-dried, sieved (mesh
 width 2 mm) and homogenized. Soil organic carbon (%) was determined using
 a Tyurin's wet combustion technique, which is based on organic carbon
 oxidation by potassium dichromate (0.4 N) in acid solution
 (K<sub>2</sub>Cr<sub>2</sub>O<sub>4</sub>: H<sub>2</sub>SO<sub>4</sub> in a 1:1 ratio). The soil pH was determined by a standard glass electrode pH meter using a <em>potassium chloride </em>solution in a 1:2 ratio (soil : 0.1-N <em>KCl).</em> Density of soil biota For the soil microbiological analysis, we counted cells of three microbial groups: heterotrophic bacteria, micromycetes, and actinomycetes. Cells were cultured on group-specific substrates under controlled temperature conditions: heterotrophic bacteria were cultured on meat-peptone agar between 28 and 30 °C, micromycetes were cultured on modified Czapek-Dox substrate with streptomycin at 20 to 25 °C, and actinomycetes were cultured on starch-ammonium agar at 28 to 30 °C. The total number of cells of all three groups was used as abundance measure for the soil microbial community (cells × 10<sup>8</sup> g<sup>-1 </sup>dry soil). We took averages across the four plots to approximate the abundance per grassland for each year. Further, the abundance data were averaged across the two sampling years. To sample earthworms we used a standard Quantitative Hand Sorting method. For this, 30×30 cm² soil blocks with a depth of 15 cm were excavated from each of three subplots in each of four plots (leading to 12 samples per grassland), and earthworms were immediately separated manually in the field and sampled into empty vials. At the same day specimens were counted in the lab, their fresh weight was determined, then they were oven-dried and their dry weight was determined. Earthworm dry weight data were calibrated to an area of 1 m<sup>2</sup>. Averages were taken across the four plots to calculate earthworm biomass per grassland (g m<sup>-2</sup>) for each year and further averaged across the two sampling years.