Internal Phosphorus Flows in Moist Tropical Forests

2 Internal Phosphorus Flows in Moist Tropical Forests 

1 Above-Ground Phosphoru.s Stocks and Soil Fertility 

Vitousek and Sanford (1986) grouped lowland forests according to the underlying soil fertility and showed that forests growing on moderately fertile soils (about 15% of the total moist tropical forest area) tend to have foliar N, P, K, Ca, and Mg concentrations higher than do those growing on the more common oxisol or ulti-sol soil types of moderate to low fertility (63% of the total moist tropical forest area). Forests on the latter tend to have foliar nutrient concentrations not very different from forests growing on the very low-fertility spodosol or psamment soil types (7% of the total moist tropical forest area Sanchez, 1976 Vitousek and Sanford, 1986). 

Foliar phosphorus concentrations typically decline with canopy depth in tropical rain forests (Lloyd et al, 1995) and so it is not straightforward to relate bulked canopy values to physiological measurements made on individual leaves. But similar 

FIGURE 1 The relationship between above ground carbon density and above ground phosphorus density for moist tropical forests growing on moderately fertile ( ) and infertile(B) soils. 

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