| Cinnamamun cassia presl is one of the valuable and non-wood forest tree species in China,which not only has high economic and social value,but also plays an important ecological function.Influence of different cuitivation densities on C.cassia presl forest in Naliang town,FangCenggang city of GuangXi province was investigated,and four different densities were assigned:density D1(10000 individuals/hm2),the density D2(3100 individuals/hm2),the density D3(2400 individuals/hm2),the density D4(2100 individuals/hm2).The difference of the yield,diameter at breast height,tree height,thick skin,biomass allocation,soil nutrient and water conservation effect were compared between different densities,and the bark yield prediction model was further fitted.The findings obtained should be helpful to explore the management density of Cultivation of Middle/Larger-diameter of C.cassia,and to provide the theoretical foundation for the cultivation of sustainable management.The results showed that:(1)The accurate prediction of the bark yield is important.Different densities of C.cassia plantation was studied;we established the bark yield model by comparing the models of linear,power,logarithm,exponential and polynomial with the measurement data of 99 tree individuals.The results showed that:we got the optimal simulation equation,it is a polynomial model of W=0.973+0.0072D2H-0.00000073(D2H)2,the correlation coefficient R2 is 0.957,the prediction accuracy of P is 96.845%,the average relative error is 2.153%,and passed the Paired sample T test,mean that the model can well predict the bark yields.(2)Different cuitivation densities of C.cassia plantation was investigated to campare the differences of the bark yield,DBH,tree height,thickness for disccution on the suitable density of the cultivation of middle/larger-diameter.The results showed that:compared to the control,the bark yield per plant of increased the number of tree plants of middle/larger-diameter timber increased,too;in the forest of three different densities after thinning,the average value of bark yield,DBH,tree height,thickness of density D3(2400 individuals/hm2)was higher than other stand densities,in which the number of tree plants with middle/lager-diameter timber were dominant.Then density D3 was the optimal retention density for cultivation of middle/larger-diameter timber.(3)Different cuitivation densities of C.cassia plantation was investigated to campare the differences of the total aboveground biomass and the biomass of each organ for the suitable density of the cultivation of middle/larger-diameter.The results showed that:the biomasses of each organ were as follows:density D3>density D1>density D2>density D4,density D3 had the maximum total biomass on the ground,which was 121.57 t-hm-1,While density D4 had the minimum,which was 93.31 t·hm-1.It was showed that the increase of density did not increase the biomass,Reasonable thinning,it can not only obtain high quality timber,but also improve the management level and increase the biomass,and density D3 was the optimum density of biomass accumulation.(4)The influence of different cuitivation densities of C.cassia plantation was investigated to campare the differences of soil and litter nutrient characteristics,and the volume,water holding capacity and storage capacity were also investigated,The result showed that after 18 years of growth,the urface(0～20 cm)soil organic matter content can still reach more than 60 g/kg,and effective P content also reached about 1.9 mg/kg,indicated that the soil of the forest land is still in good condition;Forest litter mainly included a large number of leaves,branches an capillary root litter,litter thickness reached 7～10 cm,it can still keep the soil generally moist in the non rainfall conditions,the whole litter remaining total rainfall reached 5～6 t/hm2,which had a good water conservation and soil conservation capacity. |
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