ALBERT

Description: This collection contains measurements of standing below ground biomass, belowground biomass productivity and morphological root parameters measured on 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). Since 2010, plots were weeded three times per year. The following series of datasets are contained in this collection: 1. Standing below ground biomass: Coarse and fine root biomass was measured in 2003, 2004, 2006 and 2008 in 0 - 30 cm depth. In 2011 and 2014, total root biomass was sampled down to 40 cm depth. Some years report the data divided into sublayers. Every year, several soil cores were taken per plot and pooled before the whole bulk material or a subsample was washed for roots. Roots were dried at 60 - 70 °C and weighed. Standing root biomass was calculated as g m-2. 2. Below ground biomass productivity in 0 - 30 cm depth: Coarse and fine root biomass production from June to September 2003, September 2003 to July 2004 and July 2007 to June 2008 was measured by the ingrowth core method. In 2008, the data is reported divided into sublayers. Each time, five soil cores were taken per plot and replaced by root free soil from the field site. The initially root-free ingrowth cores were removed after a while and pooled plot-wise. To extract the newly formed roots, a subsample of the bulk material was washed for roots. Roots were dried at 70 °C and weighed. Root biomass productivity was calculated as g m-2. In addition, C- (only in 2003 and 2004) and N-concentration of the fine roots was determined. 3. Morphological root parameters of newly formed roots in 0 - 30 cm depth: Root length density and mean root diameter of newly formed roots from June to September 2003 and September 2003 to July 2004 were measured by the ingrowth core method. Each time, five soil cores were taken per plot and replaced by root free soil from the field site. The initially root-free ingrowth cores were removed after a while and pooled plot-wise. To extract the newly formed roots, a subsample of the bulk material was washed and scanned. Root length and mean diameter were determined by using WinRhizo (Regent Instruments, Quebec, Canada). 4. Morphological root parameters of standing roots in 0 - 30 cm depth: In 2004, mean diameter of standing roots was measured by sampling three soil cores per plot. To extract the standing roots, a subsample of the bulk material was washed and scanned. Mean diameter was determined by using WinRhizo (Regent Instruments, Quebec, Canada).

Description: This data set contains four time series of particulate and dissolved soil nitrogen measurements 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 by bi-annual weeding and mowing. 1. Total nitrogen from solid phase: Stratified soil sampling was performed every two years since before sowing in April 2002 and was repeated in April 2004, 2006 and 2008 to a depth of 30 cm segmented to a depth resolution of 5 cm giving six depth subsamples per core. In 2002 five samples per plot were taken and analyzed independently. Averaged values per depth layer are reported. In later years, three samples per plot were taken, pooled in the field, and measured as a combined sample. Sampling locations were less than 30 cm apart from sampling locations in other years. All soil samples were passed through a sieve with a mesh size of 2 mm in 2002. In later years samples were further sieved to 1 mm. No additional mineral particles were removed by this procedure. Total nitrogen concentration was analyzed on ball-milled subsamples (time 4 min, frequency 30 s-1) by an elemental analyzer at 1150°C (Elementaranalysator vario Max CN; Elementar Analysensysteme GmbH, Hanau, Germany). 2. Total nitrogen from solid phase (high intensity sampling): In block 2 of the Jena Experiment, soil samples were taken to a depth of 1m (segmented to a depth resolution of 5 cm giving 20 depth subsamples per core) with three replicates per block ever 5 years starting before sowing in April 2002. Samples were processed as for the more frequent sampling but were always analyzed independently and never pooled. 3. Mineral nitrogen from KCl extractions: Five soil cores (diameter 0.01 m) were taken at a depth of 0 to 0.15 m (and between 2002 and 2004 also at a depth of 0.15 to 0.3 m) of the mineral soil from each of the experimental plots at various times over the years. In addition also plots of the management experiment, that altered mowing frequency and fertilized subplots (see further details below) were sampled in some later years. Samples of the soil cores per plot (subplots in case of the management experiment) were pooled during each sampling campaign. NO3‐N and NH4‐N concentrations were determined by extraction of soil samples with 1 M KCl solution and were measured in the soil extract with a Continuous Flow Analyzer (CFA, 2003–2005: Skalar, Breda, Netherlands; 2006–2007: AutoAnalyzer, Seal, Burgess Hill, United Kingdom). 4. Dissolved nitrogen in soil solution: Glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1–1.6 µm (UMS GmbH, Munich, Germany) were installed in April 2002 in depths of 10, 20, 30 and 60 cm to collect soil solution. The sampling bottles were continuously evacuated to a negative pressure between 50 and 350 mbar, such that the suction pressure was about 50 mbar above the actual soil water tension. Thus, only the soil leachate was collected. Cumulative soil solution was sampled biweekly and analyzed for nitrate (NO3-), ammonium (NH4+) and total dissolved nitrogen concentrations with a continuous flow analyzer (CFA, Skalar, Breda, The Netherlands). Nitrate was analyzed photometrically after reduction to NO2- and reaction with sulfanilamide and naphthylethylenediamine-dihydrochloride to an azo-dye. Our NO3- concentrations contained an unknown contribution of NO2- that is expected to be small. Simultaneously to the NO3- analysis, NH4+ was determined photometrically as 5-aminosalicylate after a modified Berthelot reaction. The detection limits of NO3- and NH4+ were 0.02 and 0.03 mg N L-1, respectively. Total dissolved N in soil solution was analyzed by oxidation with K2S2O8 followed by reduction to NO2- as described above for NO3-. Dissolved organic N (DON) concentrations in soil solution were calculated as the difference between TDN and the sum of mineral N (NO3- + NH4+).

Description: This data set contains information about the functional structure (overall biomass; abundance of consumers: in different habitat strata; of different food resource specialization, feeding strategies and aerial mobility) of aboveground consumers (herbivores, carnivores, omnivores and decomposers) per plots from a grassland plant diversity experiment (the Jena Experiment; Roscher et al. 2004). The experiment was established in 2002, and consists of 80 grassland plots. Plots vary in plant species richness (1, 2, 4, 8, 16, or 60 species). All plots are mown twice per year, and weeded three times per year to maintain the experimental diversity gradient. We collected ground-associated arthropods over 125 days from May until September 2010 using two pitfall traps of 4.5 cm diameter per plot. During the sampling periods, the field traps were filled with 3% formalin and after emptying the traps, animals were stored in 70% ethanol. Vegetation-associated arthropods were collected by suction sampling in early June and August (during the peak biomass of the plant communities) using a modified commercial vacuum cleaner. We randomly chose three subplots of 0.75 m x 0.75 m within each plot, covered them with a gauze cage of the same size, and sampled arthropods by vacuuming the inside of the cages until we spotted no arthropods anymore. Samples were identified to species level, except for Hymenoptera, which were identified to the level of family or subfamily. We pooled data of all sampling campaigns in 2010 and standardized the resulting abundances between zero and one, separately for pitfall and suction sampling to account for different sampling intensities between the two methods (Hertzog et al. 2016). We focused on species that we sampled more than once during the whole vegetation period.

Description: This collection contains measurements of abundance and diversity of different groups of aboveground invertebrates sampled on the plots of the different sub-experiments at the field site 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 by bi-annual weeding and mowing. The following series of datasets are contained in this collection: 1. Measurements of ant abundance (number of individuals attracted to baits) and ant occurrence (binary data) in the Main Experiment in 2006 and 2013. Ants where sampled using two types of baited traps receiving ~10g of Tuna or ~10g of honey/Sucrose. After 30min the occurrence (presence = 1 / absence = 0) and abundance (number) of ants at the two types of baits was recorded and pooled per plot.

Description: This collection contains measurements of physical and chemical soil properties on 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. The following series of datasets are contained in this collection: 1. Physical soil properties - Soil texture: Proportion of sand, silt and clay in the fine soil was measured in April 2002 before plot establishment at 27 locations distributed throughout the experimental site. Undisturbed soil cores were taken to 100 cm depth and separated in depth increments with a resolution of 10 to 20 cm. Grain size fractions according to DIN 19683-2 were then determined by a combined sieve and hydrometer analysis. Values for each plot were interpolated by ordinary kriging. - Bulk density: Bulk density was sampled down to 100 cm depth in 2002 and 30 cm depth in 2004, 2006 and 2008. Several undisturbed soil cores were taken per plot and separated in depth increments before the bulk material was sieved, dried and weighed. - Soil hydraulic properties: 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. Applied was equation four and five of Zacharias and Wessolek (2007) to derive parameters of the water retention curve. 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. -Soil porosity: the fraction of total volume occupied by pores or voids measured at matric potential 0, already published on https://doi.pangaea.de/10.1594/PANGAEA.865254. 2. Chemical soil properties - Lime content: Percentage of CaCO3 in the soil was measured in April 2002 before plot establishment at 27 locations distributed throughout the experimental site. Undisturbed soil cores were taken to 100 cm depth and separated in depth increments with a resolution of 10 to 20 cm. The bulk material was sieved and CaCO3 content of the fine soil was determined as volumetric determination according to DIN 19684-5. - Soil organic matter: Percentage of soil organic matter was measured in April 2002 before plot establishment at 27 locations distributed throughout the experimental site. Undisturbed soil cores were taken to 100 cm depth and separated in depth increments with a resolution of 10 to 20 cm. The bulk material was sieved and organic content of the fine soil was determined using a loss-on-ignition method. - Soil pH value: soil pH value was determined 2002 and 2010 in water and 2002 also in calcium chloride. Five soil samples were taken per plot and bulk material was diluted in water and calcium chloride. PH values were then measured with an electrode.

Description: This data set contains two time series of measurements of dissolved phosphorus (organic, inorganic and total with a biweekly resolution) and dissolved inorganic phosphorus with a seasonal resolution. In addition, data on phosphorus from soil samples measured in 2007 and fractionated by different acid-extrations (Hedley fractions) are provided. All data measured at 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 by bi-annual weeding and mowing. 1. Dissolved phosphorus in soil solution: Suction plates installed on the field site in 10, 20, 30 and 60 cm depth were used to sample soil pore water. Cumulatively extracted soil solution was collected every two weeks from October 2002 to May 2006. The biweekly samples from 2002, 2003 and 2004 were analyzed for dissolved organic phosphorus (DOP), dissolved inorganic phosphorus (PO4P) and dissolved total phosphorus (TDP) by Continuous Flow Analyzer (CFA SAN ++, SKALAR [Breda, The Netherlands]). 2. Seasonal values of dissolved inorganic phosphorus in soil solution were calculated as volume-weighted mean values of the biweekly measurements (spring = March to May, summer = June to August, fall = September to November, winter = December to February). 3. Phosphorus fractions in soil: Five independent soil samples per plot were taken in a depth of 0-15 cm using a soil corer with an inner diameter of 1 cm. The five samples per plot were combined to one composite sample per plot. A four-step sequential P fractionation (Hedley fractions) was applied and concentrations of P fractions in soil were measured photometrically (molybdenum blue-reactive P) with a Continuous Flow Analyzer (Bran&Luebbe, Germany).

Description: This data set contains three time series of measurements of soil carbon (particular and dissolved) 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 by bi-annual weeding and mowing. 1. Particulate soil carbon: Stratified soil sampling was performed every two years since before sowing in April 2002 and was repeated in April 2004, 2006 and 2008 to a depth of 30 cm segmented to a depth resolution of 5 cm giving six depth subsamples per core. Total carbon concentration was analyzed on ball-milled subsamples by an elemental analyzer at 1150°C. Inorganic carbon concentration was measured by elemental analysis at 1150°C after removal of organic carbon for 16 h at 450°C in a muffle furnace. Organic carbon concentration was calculated as the difference between both measurements of total and inorganic carbon. 2. Particulate soil carbon (high intensity sampling): In one block of the Jena Experiment soil samples were taken to a depth of 1 m (segmented to a depth resolution of 5 cm giving 20 depth subsamples per core) with three replicates per block ever 5 years starting before sowing in April 2002. Samples were processed as for the more frequent sampling. 3. Dissolved organic carbon: Suction plates installed on the field site in 10, 20, 30 and 60 cm depth were used to sample soil pore water. Cumulative soil solution was sampled biweekly and analyzed for dissolved organic carbon concentration by a high TOC elemental analyzer. Annual mean values of DOC are provided.

Description: This collection contains measurements of environmental conditions measured on the plots of the different sub-experiments at the field site 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 by bi-annual weeding and mowing. The following series of datasets are contained in this collection: 1.Soil temperature measurements on plots of the Main Experiment; 2. Quantification of the duration that individual plots of the Main Experiment were submerged during a flooding event occurring in June 2013

Description: This data set contains a time series of plant height measurements (vegetative and reproductive) from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In addition, data on species specific plant heights for the main experiment are available from 2002. 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 by bi-annual weeding and mowing. 1. Plant height was recorded, generally, twice a year just before biomass harvest (during peak standing biomass in late May and in late August). Methodologies of measuring height have varied somewhat over the years. In earlier year the streched plant height was measured, while in later years the standing height without streching the plant was measured. Vegetative height was measured either as the height of the highest leaf or as the length of the main axis of non-flowering plants. Regenerating height was measured either as the height of the highest flower on a plant or as the height of the main axis of flowering. Sampled plants were either randomly selected in the core area of plots or along transects in defined distances. For details refer to the description of individual years. Starting in 2006, also the plots of the management experiment, that altered mowing frequency and fertilized subplots (see further details in the general description of the Jena Experiment) were sampled. 2. Species specific plant height was recorded two times in 2002: in late July (vegetative height) and just before biomass harvest during peak standing biomass in late August (vegetative and regenerative height). For each plot and each sown species in the species pool, 3 plant individuals (if present) from the central area of the plots were randomly selected and used to measure vegetative height (non-flowering indviduals) and regenerative height (flowering individuals) as stretched height. Provided are the means over the three measuremnts per plant species per plot.

Description: This collection contains measurements on physical soil properties of the plots of the different sub-experiments at the field site 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 by bi-annual weeding and mowing