Abstract:

The accumulation, distribution and cycling of nutrient, elements were studied in a mature (21–23 yr. old)and pure stand of Cunninghamia lanceolata in Huitong County of Hunan Province, during 1980–1983. The results are summarized as follows:

1. Concentration of nutrient elements in organs of the C. lanceolata tends toward Ca>Mg>N>K>P. The highest concentrations of nutrient elements were found in the leaf and the lowest in the trunk.

2. Total accumulations of nutrient elements of tree layer, understorey layer and ground-cover layer were estimated to be 1993.83kg/ha, 34.46kg/ha and 166.91kg/ha respectively. Total accumulations of nutrient elements in one ton of standing crop were in the order of tree layer< understorey layer

3. Annual accumulations of nutrient elements in different layers in kg/ha were 112.71 for tree layer, 7.4 for understorey layer and 144.33 for ground-cover layer.

4. Annual mean amount of litterfall in the stand was 1764.35kg/ha, it appeared in two peaks in February and July. Content of nutrient elements in the litterfall was 56.07kg/ha, of which N: was 13.53, P: 3.94, K:3.49, Ca:27.17 and Mg: 7.94kg/ha.

5. Input of annual amount of nutrient elements through precipitation into the stand was 1107 ton/ha, of which N was 18.22; P, ll.10;K, 13.30; Ca, 35.09; and Mg, 43.56kg/ha.

6. Annual uptakes of nutrient elements in the stand in kg/ha was N:41.89, P:15.76, K:19.65, Ca:81.62 and Mg:46.56. The ratios of annual return and annual uptake of nutrient elements were N:0.43, P:0.49, K: 0.29, Ca:0.35, and Mg:0.39.