ALBERT

Description: This data set contains measurements of soil bulk density in different depth layers. Data presented here is from the Main Experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained in general by bi-annual weeding and mowing. Since 2010, plot size was reduced to 5 x 6 m and plots were weeded three times per year. Soil bulk density was determined in spring from undisturbed soil samples to a depth of 30 cm. Three soil cores per plot were taken with a split tube sampler with an inner diameter of 4.8 cm and separated in depth increments of five cm. The bulk material was passed through a sieve with 2 mm mesh size, dried to constant weight at 40 °C and subsequently weighed to calculate the density. Paired sampling was chosen to avoid additional spatial variability (Lal et al., 2000), which means that three of the five sampling locations of 2002 bulk density measurement, that were in the core area of the plots, were chosen for the repeated sampling. The spatial distance of the paired soil samples were less than 30 cm.

Description: This data set contains measurements of soil bulk density in different depth layers. Data presented here is from the Main Experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained in general by bi-annual weeding and mowing. Since 2010, plot size was reduced to 5 x 6 m and plots were weeded three times per year. Soil bulk density was determined in spring from undisturbed soil samples to a depth of 100 cm. Soil cores were taken with a metal bulk density ring of ten cm height and partly pooled to obtain depth increments with a resolution of ten cm from ground level to 40 cm depth and 20 cm from 40 cm to 100 cm depth. The bulk material was passed through a sieve with 2 mm mesh size, dried to constant weight at 105 °C and subsequently weighed to calculate the density. In 2002, bulk density was measured at 27 locations before plot establishment. Two of them are now reference plots and thus not included in this data set. The chosen plots represented a spatial gradient across the field site and resulted in average soil bulk density estimations at the beginning of the experiment.

Description: This data set contains measurements of soil bulk density in different depth layers. Data presented here is from the Main Experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained in general by bi-annual weeding and mowing. Since 2010, plot size was reduced to 5 x 6 m and plots were weeded three times per year. Soil bulk density was determined in spring from undisturbed soil samples to a depth of 30 cm. Three soil cores per plot were taken with a split tube sampler with an inner diameter of 4.8 cm and separated in depth increments of five cm. The bulk material was passed through a sieve with 2 mm mesh size, dried to constant weight at 40 °C and subsequently weighed to calculate the density. Paired sampling was chosen to avoid additional spatial variability (Lal et al., 2000), which means that three of the five sampling locations of 2002 bulk density measurement that were in the core area of the plots were chosen for the repeated sampling. The spatial distance of the paired soil samples were less than 30 cm.

Description: This data set contains measurements of soil bulk density in different depth layers. Data presented here is from the Main Experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained in general by bi-annual weeding and mowing. Since 2010, plot size was reduced to 5 x 6 m and plots were weeded three times per year. Soil bulk density was determined in spring from undisturbed soil samples to a depth of 30 cm. Three soil cores per plot were taken with a split tube sampler with an inner diameter of 4.8 cm and separated in depth increments of five cm. The bulk material was passed through a sieve with 2 mm mesh size, dried to constant weight at 40 °C and subsequently weighed to calculate the density.

Description: This data set contains measurements of soil texture, i. e. proportion of sand, silt and clay. Data presented here is from the Main Experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained in general by bi-annual weeding and mowing. Since 2010, plot size was reduced to 5 x 6 m and plots were weeded three times per year. Soil texture was determined from undisturbed soil cores at 27 locations distributed throughout the experimental site before plot establishment. Two of the locations are now reference plots and thus not included in this data set. Soil cores were taken to 100 cm depth and separated in increments with a resolution of ten cm from ground level to 40 cm depth and 20 cm from 40 cm to 100 cm depth. The bulk material was passed through a sieve with 2 mm mesh size and only fine soil was used for the investigation of soil texture. Grain size fractions according to DIN 19683-2 for every sample were then determined at the laboratory for geoecology of Jena University by a combined sieve and hydrometer analysis. Values for each plot were interpolated by ordinary kriging. This data set contains both, the actually measured in may as well as the interpolated values (Date/time start:01/01/2002,Date/time end:31/12/2002).

Description: This data set contains measurements of soil hydraulic properties, i. e. field capacity and permanent wilting point. Data presented here is from the Main Experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained in general by bi-annual weeding and mowing. Since 2010, plot size was reduced to 5 x 6 m and plots were weeded three times per year. Field capacity and permanent wilting point at 10, 20 and 30 cm depth were derived from soil texture data of 2002 and bulk density 2006 by using pedotransfer functions. Soil texture was determined from undisturbed soil cores at 27 locations distributed throughout the experimental site in spring 2002 before plot establishment. Soil cores were taken to 100 cm depth and separated in depth increments with a resolution of ten cm from ground level to 40 cm depth and 20 cm from 40 cm to 100 cm depth. The bulk material was passed through a sieve with 2 mm mesh size and only fine soil was used for the investigation of soil texture. Grain size fractions according to DIN 19683-2 for every sample were then determined at the laboratory for geoecology of Jena University by a combined sieve and hydrometer analysis. Values for each plot were interpolated by ordinary kriging and the interpolated values were used for the investigation of field capacity and permanent wilting point. Soil bulk density was determined from undisturbed soil samples to a depth of 30 cm. Three soil cores per plot were taken with a split tube sampler with an inner diameter of 4.8 cm and separated in depth increments of five cm. The bulk material was passed through a sieve with 2 mm mesh size, dried to constant weight at 40 °C and subsequently weighed to calculate the density. The determination of field capacity and permanent wilting point was based on pedotransfer functions described in Zacharias and Wessolek (2007). Applied was equation four (where sand content 〈= 66.5%) and five (where sand content 〉 66.5 %) to derive the parameters of the water retention curve. Bulk density for 10 cm was obtained by taking the average of the measured bulk density of 5-10 cm and 10-15 cm, similarly for 20 cm. For 30 cm, bulk density was assumed to be equal to the one measured at 25-30 cm. Water contents at field capacity and permanent wilting point were obtained using the van Genuchte Eq (e.g. eq 1 in Zacharias and Wessolek), and calculating water contents at -330 cm matric potential (field capacity, 1/3 of atmospheric pressure) and at - 15000 cm.