Directional Cultivation Technology of Pulp Forest of Populus alba × Populus berolinensis with Short Rotation

Through the selection of seedling age,determination of forestation density,mixing of forestation,nutrition element and fertilization experiments,technical measures of increasing the growth of Populus alba × Populus berolinensis and wood quality were determined.We should use the sturdy seedlings of which stem age and root age are all two years and the trees of which stem age are two years and root age are three years to conduct pulp forest of Populus alba × Populus berolinensis by the measures of orientation cultivation.The row spacing with 2m×4m,3m×4m should be used.The rotation should be 8~12 years.Agroforestry should be used in preceding 3 years.The optimum stand age for fertilization was 4~6 years.The optimum fertilizing time was the first ten days of July.The optimal fertilizing rate was N∶P∶ K=1∶0.84∶0.87.Mixing with Lespedeza bicolor,Hippophae rhamnoides should accelerate the growth of Populus alba × Populus berolinensis and decrease the plant diseases and insect pests.The biomass and efficiency for solar energy utilization were 15% higher the pure forest.