Aboveground community and species-specific plant biomass from the Jena Experiment (Main Experiment, year 2003)

This data set contains aboveground community biomass (Sown plant community, Weed plant community, Dead plant material, and Unidentified plant material; all measured in biomass as dry weight) and species-specific biomass from the sown species of 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. Aboveground community biomass was harvested twice in 2003 just prior to mowing (during peak standing biomass in late May and in late August) on all experimental plots of the main experiment. This was done by clipping the vegetation at 3 cm above ground in four rectangles of 0.2 x 0.5 m per large plot. The location of these rectangles was assigned prior to each harvest by random selection of coordinates within the core area of the plots (i.e. the central 10 x 15 m). 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 (i.e., dead plant material in the data file), and remaining plant material that could not be assigned to any category (i.e., unidentified plant material in the data file). 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 data for individual samples and the mean over samples for the biomass measures on the community level are given. Overall, analyses of the community biomass data have identified species richness as well as functional group composition as important drivers of a positive biodiversity-productivity relationship.

Pigment concentrations and biomass of phytoplankton and of its dominant species in surface Black Sea waters in 1998-2000

Data on chlorophyll a concentration and species composition and biomass of phytoplankton have been collected for two years continues monitoring in the central part and the slope zone of the Black Sea. Seasonal dynamics of chlorophyll a concentration correspond to U-type. It is characterized by low values in summer, high values in autumn, which are going to winter-spring bloom of phytoplankton. Oscillations of mean values of chlorophyll concentrations are equal to 3-4 in the central part and 2 - in the slope zone. In the autumn-winter-spring period high values of phytoplankton biomass are related to typical blooming diatom algae in the first year and other taxons - in the second year. Relationship between relative content of phaeopigment and chlorophyll concentration has been determined for the central western part of the sea. Seasonal dynamics of carbon/chlorophyll a ratio has been shown. For both regions mean values of this ratio were equal to ~20 in autumn-winter-spring time and 40-50 - in summer time.