Abstract: The studies show that in the whole community, Pis deficient, and Nand Kare basically balanced. N, Pand Kare accumulated in plant tissues and litters, but depleted in soil. Nand Pcontents in surface soil(0-20cm) are the main factors affecting crop growth, and Pcontent in20-80cm soil layer in the major one affecting Paulownia elongata growth. The absorption coefficients of N, Pand Kin the communities are respectively 0.078, 0.014 and 0.052, their utilization coefficients are respectively 0.95, 0.90 and 0.94, and their recycling coefficients are respectively 0.042, 0.05 and 0.063.

Key words: Nitrogen, Phosphorus, Potassium, Recycling, Agroforestrial ecosystem, slope., SEBAL model, elevation, light utility efficiency model, net primary productivity