Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.
The germination experiment of Chinese\|fir 〔\%Cunninghamia lanceolata \%(Lamb. ) Hook.〕 seeds treated by ferulic acid and cinnamic acid of different concentrations (0.2, 0.4 and 0.8 mg/L) with bioassay of allelopathy was carried out. The result showed that the seed germination was inhibited by ferulic acid and cinnamic acid, and the inhibition is more obvious in higher concentration than that in lower concentration.
