Dissolved organic carbon in soil solution of the Jena Experiment (Main Experiment, year 2003)

This data set contains measurements of dissolved organic carbon in samples of soil water collected 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. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 mm (UMS GmbH, Munich, Germany) were installed 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 dissolved organic carbon concentration by a high TOC elemental analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). Samples were analyzed as soon as possible and stored at 4°C if necessary. Often in summer, no free soil solution was available for collection, especially in the upper soil layers. Annual mean values of measured biweekly concentrations of dissolved organic carbon are provided.

Plant height along the plant diversity gradient in the Jena Experiment (Main Experiment, year 2004)

This data set contains measurements of plant height: vegetative height (heighest leaf) in 2004 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. In 2004, plant height was recorded twice a year just before biomass harvest (during peak standing biomass in late May and in late August). For plants at 3 random points in a control area at the margin of each experimental, vegetative height (heighest leaf) was measured as standing height (without stretching the plant). Provided are the individual measurements and the mean over the measured plants.

Consolidation properties and hydraulic conductivities of sediments from ODP Leg 207 sites

The stress history, permeability, and compressibility of sediments from Demerara Rise recovered during Ocean Drilling Program Leg 207 were determined using one-dimensional incremental load consolidation and low-gradient flow pump permeability tests. Relationships among void ratio, effective stress, and hydraulic conductivity are presented for sampled lithologic units and used to reconstruct effective stress, permeability, and in situ void ratio profiles for a transect of three sites across Demerara Rise. Results confirm that a significant erosional event occurred on the northeastern flank of the rise during the late Miocene, resulting in the removal of ~220 m of upper Oligocene-Miocene deposits. Although Neogene and Paleogene sediments tend to be overconsolidated, Cretaceous sediments are normally consolidated to underconsolidated, suggesting the presence of overpressure. A pronounced drop in permeability occurs at the transition from the Cretaceous black shales into the overlying Maastrichtian-upper Paleocene chalks and clays. The development of a hydraulic seal at this boundary may be responsible for overpressure in the Cretaceous deposits, leading to the lower overconsolidation ratios of these sediments. Coupled with large regional variations in sediment thickness (overburden stresses), the higher permeability overpressured Cretaceous sediments represent a regional lateral fluid conduit on Demerara Rise, possibly venting methane-rich fluids where it outcrops on the margin's northeastern flank.

Dissolved organic carbon in soil solution of the Jena Experiment (Main Experiment, year 2007)

This data set contains measurements of dissolved organic carbon in samples of soil water collected 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. In April 2002 glass suction plates with a diameter of 12 cm, 1 cm thickness and a pore size of 1-1.6 mm (UMS GmbH, Munich, Germany) were installed 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 dissolved organic carbon concentration by a high TOC elemental analyzer (Elementar Analysensysteme GmbH, Hanau, Germany). Samples were analyzed as soon as possible and stored at 4°C if necessary. Often in summer, no free soil solution was available for collection, especially in the upper soil layers. Annual mean values of measured biweekly concentrations of dissolved organic carbon are provided.