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.

There are two types of missing values contained in datasets from the Jena Experiment. Empty cells represent missing values that result from the design of the experiment. Empty cells result when the respective value does not occur in the design and could thus not be measured. For example, in the case of species-specific biomass cells are left blank, when the species was not sown in the respective plot. Missing values that resulted from methodological problems, sampling errors, or lost samples/data are marked with "-9999".This dataset is part of a collection of measurements of the Jena-Ecotron Experiment, which was part of the Jena Experiment.