Pre-European estimate of mean annual concentration of dissolved phosphorus in soil water (PMnlConc0.Base)

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The dissolved phosphorous (P) concentration is calculated as the ratio of the plant-available mineral P store to soil water store. Rainfall has a strong influence on the pattern of both these stores, but not on their ratio. The pattern of dissolved P concentrations is explained by the effect of air dryness (saturation deficit) on the dissolved P store (mainly controlled by NPP) which is greater than the effect of air dryness on the soil water store (mainly determined by rainfall or energy limitation). This gives a pattern of P concentration in soil water that decreases as the climate-average air dryness increases from temperate to semi-arid tropical environments. Derived from the BiosEquil model by Raupach et al. (2001a; 2001b).

Soil nutrient outputs of the BiosEquil model
Nutrient status is one of the key limiting factors determining the productivity of Australian vegetation systems, but is only broadly represented by gross nutrient status an attribute compiled from the Atlas of Australian Soils (McKenzie et al. 2000). We therefore additionally compiled the 0.05°gridded pre-European (base) predictions of carbon, nitrogen and phosphorous distributions which are outputs of the BiosEquil model by Raupach et al. (2001a; 2001b). These data are available from the Australian Natural Resources Atlas at www.nlwra.gov.au/atlas. Inputs to the pre-European models included meteorological surfaces of daily gridded data at 0.05° spatial resolution (for Australia) (Jeffrey et al. 2001), soil characteristics for current conditions derived from the Atlas of Australian Soils (McKenzie et al. 2000), and vegetation characteristics (Leaf Area Index) (Lu et al. 2001). The 0.05° gridded data were resampled to 0.01° using the cubic algorithm with RESAMPLE in ARCINFO GRID. Zero values were assumed to represent NODATA values (e.g. lakes) and were iteratively filled using the DATA option of the FOCALMEAN command with a CIRCLE expand radius of 3 cells in ARCINFO GRID, as described above.