Phosphorus nutrition of phosphorus-sensitive Australian native plants: threats to plant communities in a global biodiversity hotspot

• Published in: Conservation physiology 2013-05, Vol.1 (1), p.cot010-cot010
• Main Authors: Lambers, Hans, Ahmedi, Idriss, Berkowitz, Oliver, Dunne, Chris, Finnegan, Patrick M., Hardy, Giles E. St J., Jost, Ricarda, Laliberté, Etienne, Pearse, Stuart J., Teste, François P.
• Format: Article
• Language: English
• Subjects: Biodiversity; Environmental aspects; Environmental research; Plant nutrition; Reviews; Soil phosphorus
• ISSN: 2051-1434; 2051-1434
• DOI: 10.1093/conphys/cot010

South-western Australia harbours a biodiversity hotspot on severely phosphorus-impoverished soils. Threats include eutrophication due to phosphorus enrichment, due to increased fire frequency and spraying with phosphite to reduce the impacts of the introduced pathogen Phytophthora cinnamomi. We propose a strategy to work towards alternatives to phosphite for pathogen management.AbstractSouth-western Australia harbours a global biodiversity hotspot on the world's most phosphorus (P)-impoverished soils. The greatest biodiversity occurs on the most severely nutrient-impoverished soils, where non-mycorrhizal species are a prominent component of the flora. Mycorrhizal species dominate where soils contain slightly more phosphorus. In addition to habitat loss and dryland salinity, a major threat to plant biodiversity in this region is eutrophication due to enrichment with P. Many plant species in the south-western Australian biodiversity hotspot are extremely sensitive to P, due to a low capability to down-regulate their phosphate-uptake capacity. Species from the most P-impoverished soils are also very poor competitors at higher P availability, giving way to more competitive species when soil P concentrations are increased. Sources of increased soil P concentrations include increased fire frequency, run-off from agricultural land, and urban activities. Another P source is the P-fertilizing effect of spraying natural environments on a landscape scale with phosphite to reduce the impacts of the introduced plant pathogen Phytophthora cinnamomi, which itself is a serious threat to biodiversity. We argue that alternatives to phosphite for P. cinnamomi management are needed urgently, and propose a strategy to work towards such alternatives, based on a sound understanding of the physiological and molecular mechanisms of the action of phosphite in plants that are susceptible to P. cinnamomi. The threats we describe for the south-western Australian biodiversity hotspot are likely to be very similar for other P-impoverished environments, including the fynbos in South Africa and the cerrado in Brazil.