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The family Proteaceae dominates the nutrient-poor, Mediterranean-climate floristic regions of southwestern Australia (SWA) and the Cape of South Africa. It is well-recognised that mediterranean Proteaceae have comparatively large seeds that are enriched with phosphorus (P), stored mainly as salts of phytic acid in protein globoids. Seed P can contribute up to 48% of the total aboveground P, with the fraction allocated depending on the species fire response. For SWA species, 70–80% of P allocated to fruiting structures is invested in seeds, compared with 30–75% for Cape species, with SWA species storing on average 4.7 times more P per seed at twice the concentration. When soil P is less limiting for growth, seed P reserves may be less important for seedling establishment, and hence plants there tend to produce smaller seeds with less P. For Australian Hakea and Grevillea species the translocation of P from the fruit wall to the seed occurs in the days/weeks before final fruit dry mass is reached, and accounts for 4–36% of seed P. Seed P content increases with the level of serotiny, though it decreases marginally as a fraction of the total reproductive structure. The greater occurrence of serotiny and higher seed P content within the Proteaceae in SWA supports the notion that SWA soils are more P-impoverished than those of the Cape. [ABSTRACT FROM AUTHOR]

This paper makes a case for coupling quantitative relationships between plant function and environment with an understanding of local hydrology as a basis for selecting species for recharge control and salinity management in the cropping zone (rainfall < 500 mm per year) of south western Australia, a region with a Mediterranean-type climate. This case is made in two parts: (a) A review of some physiological responses of trees to drought and trends in these responses in relation to the rainfall patterns across the natural distribution of species. In general low-rainfall species use less water during winter and early spring and have greater physiological activity during summer than high-rainfall communities. Trends in leaf water relations and stomatal responses to soil drying are consistent with this observation; species from lower rainfall environments have lower leaf water potential at the turgor loss point and weaker stomatal responses to soil drying than those from high rainfall areas. (b) A physiological growth model for Eucalyptus globulus is used to demonstrate how a quantitative description of key plant-environment interactions may be used to analyse the growth and mortality risk for combinations of site, climate and stand management. [ABSTRACT FROM AUTHOR]