LAUSR

Aims The aims of this study were to (i) assess how the P concentration in leaves of common Australian native plant species varies across a broad geographic region that includes naturally low to naturally high P status soils; and (ii) investigate whether there is a connection between P speciation and P concentration in these leaves. Methods An ecological transect along the western edge of the Great Dividing Range was sampled for soil and leaf material of four genera ( Acacia , Callitris , Einadia and Eucalyptus ). Soil and leaf samples were analysed for total P, while 31 P nuclear magnetic resonance ( 31 P NMR) spectroscopy was used to determine P speciation in leaves. Results Soil P concentration was influenced by parent material, with soils developed on basalt particularly high in P. Leaf P concentration also varied, but this variation was poorly correlated with soil P concentration. Solution 31 P NMR demonstrated uniformity in biochemical partitioning of leaf P. Concentrations of ‘biochemical’ organic P (phospholipid-P and RNA-P) in leaves were relatively constant at 200–300 mg kg −1 , while concentrations of ‘storage’ P forms (orthophosphate-P and phytate-P) increased with increasing total leaf P concentration and reached values >2000 mg kg −1 . Conclusions These findings improve understanding of P cycling in native Australian ecosystems. Adaptation to the highest P sites resulted in accumulation of storage P forms, rather than down-regulating P uptake. At most sites, plants act as P pumps, shifting sparsely available P into the topsoil, by accumulating more P than they need and eventually shedding it in litter.