Abstract: Taking the 10-, 23-, and 45-year-old -Pinus massoniana- plantations in Huitong of Hunnan Province as test objects and with the parameters nutrient content per unit needle mass, nutrient content per unit needle length, and nutrient content of single needle, the nutrient contents and resorption characteristics in the needles of different age P. massoniana before and after withering were studied. The results showed that after withering, the mass of single needle, length of single needle, and mass per unit needle length were decreased by 15.9%, 4.6% and 13.9%, respectively. The nutrient contents in the needles differed with the age of P. massoniana, and the mean resorption of N, P and K in the needles was all higher than 50%. With the increase of tree age, the nutrient resorption efficiency and proficiency increased first and declined then. According to the calculations with the parameters mentioned above, there was no significant difference in the resorption efficiency of the nutrients except N.

Key words: thinning, Chinese fir, root branch order, biomass, morphological trait.