RESUMEN
Taking the soils developed from two kinds of parent materials (granite and limestone) under Pinus tabulaeformis forest at the same altitude in Songshan Mountain Nature Reserve of Beijing as test objects, this paper studied the vertical distribution patterns of soil total nitrogen, available phosphorus, and available potassium. The soil developed from granite had the total nitrogen, available phosphorus, and available potassium contents being 1.61-2. 35 g kg-1, 5. 84-10.74 mg kg- 1, and 39.33-93.66 mg kg-1, while that developed from limestone had the total nitrogen, available phosphorus, and available potassium contents being 1. 69 -2. 36 g kg-1, 4.45-8.57 mg . kg-1, and 60.66-124.00 mg kg-1, respectively. The total nitrogen, available phosphorus, and available potassium contents in the two soils were the highest in 0-10 cm layer, decreased with increasing depth, and had significant differences between different layers, showing that the soil total nitrogen, available phosphorus, and available potassium had a strong tendency to accumulate in surface layer. Such a tendency was more obvious for the soil developed from limestone. The paired t-test for the two soils indicated that the total nitrogen content in different layers had no significant difference, whereas the available phosphorus content in 0-10 cm layer and the available potassium content in 10-20 cm layer differed significantly.