3.1 Effects of increasing stand ages on the nutrient concentrations and ratios in leaves and aboveground productivity
Increasing stand ages did not affect leaf P concentrations but significantly reduced leaf N concentrations and the N:P ratio (Figure 1b and f, P < 0.05). Additionally, increased leaf C concentrations and C:N ratios were found in C. hystrix plantations with increasing stand ages (Figure 1a and d, P < 0.05).
Increasing stand ages significantly reduced the aboveground productivity (Figure 2a, P < 0.05). The aboveground productivity was positively correlated with leaf N:P ratios (Figure 2b, P< 0.01).