Study On The Effect Of Different Stand Density And Fertilization Intension In Acacia Mearnsii Young Plantation

Acacia mearnsii is a fast-growing tree with hard material and tannin extract.It is a dual-purpose of wood and tannin extract tree species with high economic value.In this paper,under the interaction of three different stand densities and three different fertilization levels,the stand structure,DBH,tree height,crown width as well as the amount of volume,biomass,tannin yield and proanthocyanidin yield per plant and per unit area of Acacia mearnsii were studied,and the economic benefits of different treatments were analyzed for selecting the most suitable growth mode of Acacia mearnsii to provide theoretical basis for economic benefits.The main conclusions are as follows:(1)Through the change of stand structure,it was shown that the decrease of stand density and the increase of fertilizer level could increase the timber yield of large size of Acacia mearnsii.Therefore,under the treatment of low density and high fertilization,it is most suitable for the output of large-specification wood rate of Acacia mearnsii to reach the maximum value under the treatment of density 2 m×4 m and fertilization 1 kg(D3W3).Crown width reached the maximum value under the treatment of density 2 m×3 m and fertilization 1 kg(D2W3).The volume of individual plant was determined by both average tree height and DBH.In this study,the change of average tree height and DBH were basically the same,and reached the maximum value under the treatment of density 2 m×4 m and fertilization 1 kg(D3W3).For the stand volume,when the density was 2 m×2 m(D1),increasing the fertilizer level was more suitable for stand volume.(2)The biomass per plant,tannin yield per plant and proanthocyanidin yield per plant increased with the increase of fertilization and the decrease of density.The correlation between biomass per plant and density was high,and reached the maximum under D3W3 treatment.The biomass per unit area,tannin yield per unit area and tannin proanthocyanidin yield per unit area increased with the increase of fertilization and density,reacheing the maximum under the treatment of density 2 m×2 m and fertilization 1 kg(D1W3)treatment.The results showed that the indices of Acacia mearnsii per unit area were maximized under D1W3 treatment,and those of Acacia mearnsii per plant were maximized under D3 W3 treatment.(3)Comparing the growth indices of Acacia mearnsii under different densities and treatments,evaluating its economic benefits.Considering the input cost,the D3W3 treatments was the most suitable for Acacia mearnsii to grow and produce economic benefits.At the same time,by adjusting density and fertilization,the growth and accumulation of Acacia mearnsii,tannin yield and proanthocyanidin yield can reach the same level indicating that different thinning and tending methods can achieve the same economic benefits according to the local stand density and soil fertility,which is important for the specific production practice.