| Eucalyptus cloeziana is one of the most valuable large-diameter tree with high growth rate and excellent material,and has a broad development prospect.Therefore,the difference of stand vegetation and soil of Eucalyptus cloeziana in different afforestation densities and pruning intensities was analyzed in this paper,taking Eucalyptus cloeziana plantation in Qipo Forest Farm in Guangxi as the research object.To study the optimal pruning intensity and density effect of suitable Eucalyptus cloeziana plantation,the diversity of understory vegetation,average tree height,average diameter at breast height(DBH),individual volume,storage per unit area,soil enzyme activity and soil nutrient content were analyzed,under D1(2m×3m),D2(2.5m×3m)and D3(3m×3m)of afforestation densities and unpruned(CK),1/2 pruned and 1/3 pruned.The aim is to improve the timber yield and soil fertility of Eucalyptus cloeziana plantation,achieve higher economic value and ecological benefit,which providing technical reference for further optimizing the management measures of Eucalyptus cloeziana plantation.The main findings are as follows:1.The average tree height,DBH and individual volume increased with the decrease of density,but the difference was not significant,and the change rule of storage per unit area was opposite.Under high density D1 and D2,the tree height grew faster at 1/2 pruning height,while the tree height in the unpruned stand was higher than that in the pruned stand at D3.DBH and individual volume increased with the increase of pruning intensity,and DBH and individual volume were lower under D3 afforestation density and 1/3 pruning treatment than CK.2.Afforestation density and pruning intensity had extremely significant effects on soil urease and acid phosphatase activities,and pruning intensity had more significant effects on soil urease and acid phosphatase activities than afforestation density,and their interaction had extremely significant effects on soil urease and acid phosphatase activities.The enzyme activities of the two kinds of soil were higher in topsoil than in deep soil,and higher in low density and pruning treatment.3.The pH value of topsoil was lower than that of deep soil.With the increase of afforestation density,the pH value of soil also increased,but the CK under D3 density and 1/3 pruning intensity did not show a similar rule.The soil pH value was lower under 1/2 pruning treatment.4.The soil nutrients were higher under medium and low density and pruning and tending,and the soil nutrients were higher in topsoil than in deep soil.When the afforestation density was same,the soil nutrient content of pruned stand was higher than that of unpruned,and which increased with the decrease of density.However,available potassium was also higher under the density of D1 afforestation,and available phosphorus was higher under the density of D2 afforestation.The effect of pruning intensity on available phosphorus content was greater.5.The species of herb layer was higher than shrub layer under D1 density treatment,but with the decrease of density,the species and number of shrub layer increased gradually,and the species and number of pruning treatment were higher than that of unpruning.The variation of herb layer species with pruning intensity was not obvious,but the number increased with the increase of density.The diversity index of Shannon-Wiener and Simpson increased with the decrease of afforestation density in herb layer and shrub layer.The Shannon-Wiener diversity index increased with the increase of pruning intensity in herb layer,but reached the maximum value under 1/3 pruning treatment in shrub layer.The evenness of plants in shrub layer was higher than in herb layer.6.D3 density treatment had the best comprehensive effecton the growth,soil nutrients,enzyme activities and understory vegetation diversity of Eucalyptus cloeziana were,and 1/2 pruning was better than 1/3 pruning,which were all better than CK. |
PDF Full Text Request