Growing in phosphorus‐impoverished habitats in south‐western Australia: How general are phosphorus‐acquisition and ‐allocation strategies among Proteaceae, Fabaceae and Myrtaceae species?

Abstract

AbstractNumerous phosphorus (P)‐acquisition and ‐utilisation strategies have evolved in plants growing in severely P‐impoverished environments. Although these strategies have been well characterised for certain taxa, like Proteaceae, P‐poor habitats are characterised by a high biodiversity, and we know little about how species in other families cope with P scarcity. We compared the P‐acquisition and leaf P‐allocation strategies of Fabaceae and Myrtaceae with those of Proteaceae growing in the same severely P‐impoverished habitat. Myrtaceae and Fabaceae exhibited multiple P‐acquisition strategies: P‐mining by carboxylates or phosphatases, P uptake facilitated by carboxylate‐releasing neighbours, and dependence on the elevated soil P availability after fire. Surprisingly, not all species showed high photosynthetic P‐use efficiency (PPUE). Highly P‐efficient species showed positive correlations between PPUE and the proportion of metabolite P (enzyme substrates), and negative correlations between PPUE and phospholipids (cellular membranes) and nucleic acid P (mostly ribosomal RNA), while we found no correlations in less P‐efficient species. Overall, we found that Myrtaceae and Fabaceae used a wider range of strategies than Proteaceae to cope with P scarcity, at both the rhizosphere and leaf level. This knowledge is pivotal to better understand the mechanisms underlying plant survival in severely nutrient‐impoverished biodiverse ecosystems.