[Soil C:N:P stoichiometry and nutrient dynamics in Cunninghamia lanceolata plantations during different growth stages]

Abstract

We investigated soil C:N:P stoichiometry and nutrient dynamics of Cunninghamia lanceolata plantations at different stand ages (5, 8, 21, 27 and 40 years old) in Fujian Baisha Fores-try Farm. We measured the concentrations of soil total carbon (TC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), total calcium (Ca), total magnesium (Mg), and soil C:N:P stoichiometry at 0-10, 10-20, and 20-40 cm soil layers during different growth stages. The results showed that soil TC and TN concentrations and C:N remained unchanged during stand development. Soil TP content showed an increase-decrease-increase trend with increasing stand ages. Soil TP content was lowest, whereas C:P and N:P were highest at the mature stage of C. lanceolate plantation in the 0-10 and 10-20 cm soil layers. However, soil TP content showed no significant differences in all stand ages at the 20-40 cm soil layer. The contents of Ca and Mg were lowest at the mature stage of C. lanceolata stand. The TC was positively correlated with soil C:N, C:P and N:P. The TP was significantly and negatively correlated with soil C:P and N:P. Soil TP was a key factor regulating soil C:P and N:P stoichiometry. The development of mature plantation was mainly limited by soil P availability. To sustain the development of C. lanceolata plantations and improve nutrient cycling, phosphorus fertilizer could be applied during the rapid growth period of C. lanceolata. In addition, an appropriate extension of the rotation period of C. lanceolata plantation could facilitate soil nutrient restoration.

Keywords: Cunninghamia lanceolata; nutrient limitation; stand age.