Morphological root parameters of standing roots from the Jena Experiment (Main Experiment, year 2004)

This data set contains measurements of diameter of standing roots. 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 in general by bi-annual weeding and mowing. Since 2010, plots were weeded three times per year.In September 2004, three soil cores with a 4.8 cm diameter per plot were taken to 30 cm depth. The bulk material of the pooled cores was cut with scissors to < 1 cm pieces. A subsample of 50 g was suspended in water and rinsed over a 0.5 mm screen. Roots collected in the screen were transferred into a water-filled clear acrylic tray and scanned. Mean diameter of the roots was determined by using WinRhizo (Regent Instruments, Quebec, Canada).