| Abstract: | Abstract. The three most extensive spinifex alliances in arid Australia are characterised across a spectrum of post-fire successional states by their plant species, soil chemical characteristics and rainfall. Mean annual rainfall and some nutrients are correlated with the distributions of the alliances; the Triodia pungens alliance occurs in the highest rainfall region with the highest nutrient levels, the Plectrachne schinzii alliance in the mid-rainfall region with medium nutrient levels, and the T. basedowii alliance in the lowest rainfall region with a wide range of nutrient levels. This control on distribution can be over-ridden by topographic position. Where the T. pungens alliance occurs in low rainfall areas it is on sites favoured by soil moisture concentrations higher than the surrounding areas. Non-spinifex plant species are weakly associated with these alliances and their distributions relate to mean rainfall. Soil nutrient levels are generally low and, except for carbon, do not differ significantly between alliances. Soil grain sizes do not differ between alliances. |
