ALBERT

Description: This data set contains information on vegetation cover, i.e. the proportion of soil surface area that is covered by different categories of plants per estimated plot area. Data was collected on the plant community level (sown plant community, weed plant community, dead plant material, and bare ground) and on the level of individual plant species in case of the sown species. 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 by bi-annual weeding and mowing. In 2009, vegetation cover was estimated twice in May and August just prior to mowing (during peak standing biomass) on all experimental plots of the Main Experiment. Cover was visually estimated in a central area of each plot 3 by 3 m in size (approximately 9 m²) using a decimal scale (Londo). Cover estimates for the individual species (and for target species + weeds + bare ground) can add up to more than 100% because the estimated categories represented a structure with potentially overlapping multiple layers. In 2009, in addition to the four community level cover estimates, cover of the moss layer was estimated.

Description: 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.