A survey of leaf phosphorus fractions and leaf economic traits among 12 co-occurring woody species on phosphorus-impoverished soils

Background and AimsThe leaf economic spectrum (LES) is related to dry mass and nutrient investments towards photosynthetic processes and leaf structures, and to the duration of returns on those investments (leaf lifespan, LL). Phosphorus (P) is a key limiting nutrient for plant growth, yet it is unclear how the allocation of leaf P among different functions is coordinated with the LES. We addressed this question among 12 evergreen woody species co-occurring on P-impoverished soils in south-eastern Australia.MethodsLeaf 'economic' traits, including LL, leaf mass per area (LMA), light-saturated net photosynthetic rate per mass (A(mass)), dark respiration rate, P concentration ([P-total]), nitrogen concentration, and P resorption, were measured for three pioneer and nine non-pioneer species. Leaf P was separated into five functional fractions: orthophosphate P (P-i), metabolite P (P-M), nucleic acid P (P-N), lipid P (P-L), and residual P (P-R; phosphorylated proteins and unidentified compounds that contain P).ResultsLL was negatively correlated with A(mass) and positively correlated with LMA, representing the LES. Pioneers occurred towards the short-LL end of the spectrum and exhibited higher [P-total] than non-pioneer species, primarily associated with higher concentrations of P-i, P-N and P-L. There were no significant correlations between leaf P fractions and LL or LMA, while A(mass) was positively correlated with the concentration of P-R.ConclusionsAllocation of leaf P to different fractions varied substantially among species. This variation was partially associated with the LES, which may provide a mechanism underlying co-occurrence of species with different ecological strategies under P limitation.

Automated summary

The allocation of leaf phosphorus (P) among different functions is coordinated with the leaf economic spectrum (LES) and plays a role in determining the co-occurrence of different species under P limitation. Pioneers exhibited higher total P concentration, particularly in fractions such as orthophosphate P (P-i), nucleic acid P (P-N) and lipid P (P-L), compared to non-pioneer species.