Pre-European estimate of mean annual concentration of mineral nitrogen in soil water (NMnlConc0.Base)

The dissolved nitrogen (N) concentration is calculated as the ratio of the mineral N store to soil water store, which assumes that the entire mineral N is in solution. Rainfall has a strong influence on the pattern of both these stores, but not on their ratio. The pattern of mineral N concentrations is explained by the effect of air dryness (saturation deficit) on the mineral N 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 N 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.

溶解态氮（N）浓度的计算方式为矿质氮储量与土壤水分储量的比值，该计算假设所有矿质氮均处于溶解状态。降雨对这两种储量的分布模式均有显著影响，但对其比值无影响。矿质氮浓度的分布模式可通过空气干燥度（饱和差）对矿质氮储量（主要受净初级生产力（NPP）控制）的影响来解释，且这种影响大于空气干燥度对土壤水分储量（主要由降雨或能量限制决定）的影响。由此形成的土壤水中氮浓度分布模式为：从温带环境到半干旱热带环境，随着气候平均空气干燥度的增加，氮浓度逐渐降低。该数据源自Raupach等人（2001a；2001b）提出的BiosEquil模型。

BiosEquil模型的土壤养分输出结果
养分状况是决定澳大利亚植被系统生产力的关键限制因素之一，但目前仅通过总养分状况这一属性（源自《澳大利亚土壤图集》（McKenzie等人，2000））进行大致表征。因此，我们额外编译了0.05°网格分辨率的欧洲殖民前（基准）碳、氮、磷分布预测数据，这些数据是Raupach等人（2001a；2001b）提出的BiosEquil模型的输出结果。该数据可从澳大利亚自然资源图集获取，网址为www.nlwra.gov.au/atlas。欧洲殖民前模型的输入数据包括：澳大利亚地区0.05°空间分辨率的日网格气象面数据（Jeffrey等人，2001）、源自《澳大利亚土壤图集》（McKenzie等人，2000）的当前土壤特征数据，以及植被特征数据（叶面积指数（Leaf Area Index））（Lu等人，2001）。0.05°网格数据通过ARCINFO GRID中的RESAMPLE工具采用三次算法重采样至0.01°分辨率。零值被假设为代表无数据值（如湖泊区域），并采用上述方法，通过ARCINFO GRID中FOCALMEAN命令的DATA选项，以3个单元格的圆形扩展半径进行迭代填充。