Studies On The Biologic Growth Characteristic And Nutrition Of P. Bournei Plantations Under Different Stand Densities And Sites

The growth and nutrition of 37-year-old P. bournei plantations were studied, which were under similar managements in different densities and sites in Shunchang Forestry Farm in Fujian province. Results were as follows:The effect of stand density on P. bournei's diameter growth was considerable. The diameter breast-high decreased as the stand density increased. There was slight effect of the density on the height growth.Phoebe bournei plantations at higher density (2200～2400 tree-hm2) grew faster than those at lower density(1500～1650 tree-hm-2). The quantitative maturities of the height growth under different stand densities were quite different. The quantitative maturity at higher stand density was in the 14th year and that at lower stand density was in the 8th year. There was a considerable effect of the stand density on the volume growth. The volume growth at higher stand density was some faster than that at the lower in the first 20 years after planting. After this, the volume growth at lower stand density was faster than that at the higher. The quantitative maturity of volume growth at the lower stand density occurred after 37 years while that at the higher stand density needed 21 years.The growth of diameter breast high, height, and volume of P. bournei was faster as site quality was improved. The quantitative maturity of diameter breast-high was in the 15th year under typeⅡwoodland, in the 11th year for typeⅢwoodland,and in the 9th year for typeⅣwoodland. The quantitative maturity of height was in the12th year for typeⅡwoodland, in the 8th year for typeⅢwoodland, in 6th year for typeⅣwoodland. The quantitative maturity of volume did not arrive in the 37th years for typeⅡwoodland, while it occurred in 19th year for typeⅢwoodland, in the 23rd year for typelV woodland.The stand productivity increased as the stand density increased. There were the different effects of the stand density on its productivities and its allot rate of organs. The nutrient utilization ratio increased to some extent in arbor layer, brush layer and herb layer as the stand density increased.There was considerable effect of site quality on the productivity of P. bournei. There was remarkable difference in the annual net productivities of arbor layer, brush layer and herb layer under different sites. And the productivity increased as site quality was improved. In general, the more the annual net nutrient accumulation was, the more the annual net productivity was. The productivity of the arbor layer increased remarkably as site quality was improved, but the annual net nutrient accumulation of the layer decreased as site quality was improved. So the improvement of site quality was beneficial to the increase of the annual net nutrient utilization ratio of the layer.The annual net nutrient accumulations were greater in the brush layer and herb layer and there were quite difference of P. bournei plantation under sites. There was remarkable positive correlation between annual net nutrient accumulation and annual net productivity of the organs in the arbor layer of P. bournei plantation under sites. There was considerable difference in the annual net productivity and annual net nutrient accumulation of the same organ under sites. The improvement of site quality was beneficial to the annual net nutrient accumulation of the arbor layer.There was difference between the productivity of mean tree and each nutrient element accumulation of its leaf of P. bournei plantation. The annual net nutrient accumulation of each nutrient element at lower stand density was more than that at the higher except Ca and Mg. The annual net nutrient accumulation of each organ increased except bark as the stand density increased. There was difference in the nutrient utilization ratio of the same organ under stand densities.The annual net nutrient accumulation of each nutrient element of the arbor layer decreased as site quality was improved. And there was a similar trend to the annual net nutrient accumulation of each organ of the arbor layer. There was difference in the nutrient utilization ratio of the each element of P. bournei under sites. The nutrient utilization ratio of the each element of P. bournei increased except Mn as site quality was improved.