Nutrient element cycling and density effect in Pinus tabulaeformis plantations

Based on the method of tally stem analysis and chemical analysis, the accumulated contents and biological cycle of eight nutrient elements (Ca, K, Mg, Cu, Fe, Mn, P, Zn) in tree stems from three 37 years old experimental Chinese pine plantations with different density (900, 1 500, 2 000 trees/hm²) at the Badaling Forestry Centre in Beijing, were investigated.Resultsshowed that the plantation with 1 500 trees/hm² possessed the largest amount of accumulated nutrient elements and absorption as well as the highest efficiency in the use of nutrient elements. It suggests that the most rational density of Chinese pine plantations in the Badaling district is 1 500 trees/hm².