Theoretical diagram of expected types of C and P co-limitation of bacteria based on the trophic-nature gradient.

<p>The diagram represents the different types of expected co-limitation according to the trophic-nature gradient (Y-axis), indicated by the colour gradient from dark brown (maximum heterotrophy) to dark green (maximum autotrophy). The diagonal dashed line arrow crossing the diagram represents the trophic-state gradient (X-axis) in the sense of more autotrophy more eutrophy, as found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099288#pone.0099288-MedinaSnchez1" target="_blank">[32]</a>, which does not reflect the major role of trophic-nature gradient found in the present study. The squares with dashed lines include: (i) the single resource expected to be more limiting, according the trophic nature axis; (ii) the name of the expected co-limitation type <i>sensu </i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099288#pone.0099288-Harpole1" target="_blank">[47]</a>, and its meaning as effects of the treatments. The circles represent the position found for the ecosystems according to both axes; brown circle is the hetero-eutrophic ecosystem (Cubillas), green circle is the auto-oligotrophic ecosystem (La Caldera).