Model predictions for N vs. P limitation in the youngest Hawai’i and Franz Josef sites.

Axes and equations are as in Fig. 5, but with Hawai’i in a solid line and closed circle and Franz Josef in a dotted line and open circle. At the beginning of primary succession the Hawai’i site would be N limited but fairly close to co-limitation, whereas the Franz Josef site would be strongly N limited without any symbiotic N fixation. Input and nutrient use efficiency parameters come from the 300 year old Hawaiian site (I_N = 9.6 kg N ha⁻¹ y⁻¹, I_P = 0.63 kg P ha⁻¹ y⁻¹, ω_N = 382 g C g N⁻¹, ω_P = 6780 g C g P⁻¹ [37]) and the 5–7 year old New Zealand site (I_N = 1.5 kg N ha⁻¹ y⁻¹ [78], I_P = 2.2 kg P ha⁻¹ y⁻¹–calculated from the decrease in soil inorganic P from the 5 to the 60 year old site–ω_N = 45 g C g N⁻¹, ω_P = 643 g C g P⁻¹ [5]), with the other parameters as in Fig. 5a.