For this figure, the scientist had the unique visual puzzle of needing to show how these three settings compared in terms of data (Predicability to Spatial Scale), but it was also important to include a literal representation of the spatial scale that the line graph references. In this case, when sampling soil in too small of an area, the results are unpredictable. The predictability improves when the sample area is increased (and more samples included), but it is also possible to increase the sample area so much that it then includes different ecosystems, making the data unpredictable again because the separate ecosystems are too different to yield any consistent conclusion about the nature of the soil.
