Effects Of Fertilization And Forest Ground Clearance Methods On Growth And Coniferous Nutrient Contents Of Young Pinus Tabulaeformis Plantation

In order to explore the effects of fertilization and forest clearance on the growth of young Pinus tabulaeformis forest and the nutrient content of needles.We carried out fertilization experiments(nitrogen fertilizer,phosphate fertilizer)and ground clearance experiments(comprehensive clearance and strip clearance)on the seven-year old P.tabulaeformis,and analyzed the indexes of P.tabulaeformis height,DBH,crown width,current branch length,and the variation law of nutrient content of conifers in different periods.Finally,it can provide technical support for promoting the growth of P.tabulaeformis Plantation.(1)Fertilization can promote the growth of tree height,DBH,crown width and annual branch length.The annual growth of N2P2 in sunny slope,tree height,DBH and crown were 56.64 cm,1.74 cm and 45.69 cm respectively.The annual growth of N2 in shady slope tree height,DBH and crown were 61.67 cm,1.63 cm and 48.56 cm respectively.Among them,N2P2 treatment in sunny slope and N2 treatment in shady slope were higher than other fertilization treatments in tree height,DBH,crown width and annual branch length growth.Increasing the application rate of nitrogen fertilizer is beneficial to the growth of crown width of P.tabulaeformis.The growth of height and DBH of young P.tabulaeformis forest in sunny slope were higher than that on shady slope,but the growth of crown and branch length were lower than that on shady slope.(2)Fertilization can promote the accumulation of total nitrogen,total phosphorus and total potassium in needles of young P.tabulaeformis forest.The total nitrogen accumulation of needles treated with N2P2 in sunny slope was 0.576 mg g-1,which increased by 40.34% compared with the control.Total phosphorus accumulation of needles was 0.175 mg g-1,which increased by 23.81% compared with the control.Total potassium accumulation of needles treated with N1P2 was 1.208 mg g-1,which increased by 98.68% compared with the control.The accumulation of total nitrogen and total phosphorus in needles treated with N2P2 in shady slope was 0.527 mg/g-1,which increased by 126%,1.333 mg/g-1,18.49% and 0.187 mg/g-1 respectively.The accumulation of total nitrogen and total phosphorus in needles of young P.tabulaeformis forest in sunny slope waere44.96% higher than that in shady slope,however,the accumulation of total potassium in needles of young P.tabulaeformis forest in sunny slope were lower than that in shady slope.In sunny slope,the accumulation of total nitrogen,total phosphorus and total potassium in needles treated with N2P2 were higher than that of other treatments.(3)The two clearing methods can promote the DBH growth obviously,but have no obvious promoting effect on tree height,crown width and branch growth of young P.tabulaeformis forest.The growth of tree height and branch length of P.tabulaeformis in sunny slope were higher than that in shady slope,while the growth of DBH and crown width were lower than that in shady slope.The two clearing methods can promote the accumulation of total nitrogen,total phosphorus and total potassium in needles of P.tabulaeformis in shady or sunny slope.The promotion of total nitrogen accumulation by comprehensive clearance was obvious,and the accumulation of total phosphorus and total potassium by strip clearance was obvious in P.tabulaeformis needles.The increase of total nitrogen and total phosphorus in needles of P.tabulaeformis in sunny slope was higher than that on shady slope.