ALBERT

Beschreibung: This data set contains aboveground community plant biomass (Sown plant community, Weed plant community, and Dead plant material; all measured in biomass as dry weight) and species-specific biomass from the sown species of the dominance experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the dominance experiment, 206 grassland plots of 3.5 x 3.5 m were established from a pool of 9 plant species that can be dominant in semi-natural grassland communities of the study region. 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, 3, 4, 6, and 9 species). Plots were maintained by bi-annual weeding and mowing. Aboveground community biomass was harvested twice in May and August 2003 on all experimental plots of the dominance experiment. This was done by clipping the vegetation at 3 cm above ground in two rectangles of 0.2 x 0.5 m per experimental plot. The location of these rectangles was assigned by random selection of coordinates within the central area of the plots (excluding an outer edge of 50cm). The positions of the rectangles within plots were identical for all plots. The harvested biomass was sorted into categories: individual species for the sown plant species, weed plant species (species not sown at the particular plot), detached dead plant material, and remaining plant material that could not be assigned to any category. All biomass was dried to constant weight (70°C, 〉= 48 h) and weighed. Sown plant community biomass was calculated as the sum of the biomass of the individual sown species. The mean of both samples per plot and the individual measurements are provided in the data file. Overall, analyses of the community biomass data have identified species richness and the presence of particular species as an important driver of a positive biodiversity-productivity relationship.

Beschreibung: This dataset contains specific leaf area and leaf dry matter content in the Jena-Ecotron Experiment in 2012. This experiment was conducted in the Montpellier European Ecotron (CNRS, France), an advanced controlled environment facility for ecosystem research, and aimed at understanding the impact of plant species richness (4 vs. 16 species) for ecosystem carbon and water fluxes. The soil monoliths used in this experiment contained plant communities originating from the long- term Jena Experiment (50°57.1' N, 11°37.5' E, 130 m above sea level; mean annual temperature 9.3°C, mean annual precipitation 587 mm) established in May 2002. Twelve plots were selected for the Jena-Ecotron study according to the following criteria: (1) the four functional groups grasses, legumes, small and tall herbs were present, (2) realized species numbers were close to sown species richness, and (3) plots were equally distributed across the experimental field site to account for different soil textures. Large monoliths (2 m² surface area, diameter of 1.6 m, 2 m depth with a weight of 7 to 8 tons) including intact soil and vegetation were excavated in December 2011 and placed in lysimeters. In March 2012, before the start of the vegetation growth, the lysimeters were transported and installed in the Macrocosms platform of the Montpellier European Ecotron. To assess specific leaf area and leaf dry matter content, bulk samples of fully expanded leaves (1 to 7 leaves per plot and species) of the upper shoot part of all available plant species were collected during three days of the Ecotron campaign 2012 (combined with the measurements of stomatal conductance and leaf greenness). Bulk samples were put into moist paper in sealed plastic bags and stored in a cool box (refrigerator respectively) until sample processing in the laboratory. In the laboratory leaves were dried with tissue paper to remove any surface water and weighed immediately to determine their water-saturated fresh weight. The number of leaves per bulk sample was counted and leaf area was determined with a leaf area meter (LI-3000A, Licor, USA). Samples were overn-dried (70°C, 48h) and there dry mass was measured. Leaves of forb species were measured including petioles and rachis; in Galium mollugo a complete whirl was considered as a leaf. Leaf blades were measured as "leaves" in grass species., Instruments: LI-3000A, Licor, USA. Leaf dry matter content (= dry mass per unit fresh mass, LDMC; mg g-1) and specific leaf area (= leaf area per unit dry mass, SLA; mm2 mg-1) were calculated from these samples. Leaf samples were milled to a fine powder and analysed with an elemental analyzer (Flash EA 1112, Thermo Italy, Rhodano, Italy) to obtain leaf nitrogen (Nleaf; %) and carbon (Cleaf; %) concentrations.