Figure 1. Schematic diagram of Ellenberg's water table depth gradient experiment.

The diagram shows the concrete tank from above (top) and the side (below) following Ellenberg (1953, 1954) and Schulze and Beck (2002). Note that the compost layer is on top of the sand, not underneath it as shown in Schulze and Beck (2002). The concrete tank was divided into two halves filled to varying depth with either loam or sand to generate increasing distance to the water table. Each half was divided into strips sown either as monocultures of individual species (4 in 1953, as shown here, 6 in 1952, see Figure S1) or a mixtures of all species combined.