Research On Pruning Mechanism And System Of Pruning Technology Of Poplar Plantation

In this paper, the plantations (different density) of poplar clone I-69(P. deltoides Bartr. cv.'Lux')and poplar clone107(Populus×euramericana cv.'Neva') were taken as the object ofstudy, the leaves' photosynthesis characteristics and variation of nutrition element contents ofdifferent canopy layers, the cealescence process of pruning wounds, the influence of differentpruning treatments or ways on trunk's growth quantity and aboveground biomass of whole tree,the pruning mechanism and the system of pruning technology were researched, and the researchresults showed:1. The difference of leaves' photosynthesis characteristics and microclimate characteristics ofdifferent canopy layers were significant. The photosynthesis capacity of leaves of three layers ofwhorled branches from the bottom up (named as canopy layer Ⅰ, Ⅱ, Ⅲ) in poplar clone I-69and poplar clone107was: canopy layer Ⅲ＞Ⅱ＞Ⅰ. The leaves' growth status and the conditionof water and heat among different canopy layers were: canopy layer Ⅲ was the best, canopylayer Ⅱ was second and canopy layer Ⅰ was worst.2. The variation of nutrition element content of leaves of different canopy layers weredifferent, the leaves' nutrient status of canopy layer Ⅲ were the best, canopy layer Ⅱ weresecond, canopy layer Ⅰwere the worst.3. The cealescence process of poplar pruning wounds was closely connected with the varietyof poplar clones and the width of pruning wounds, the more appropriate initial pruning age forbranches of canopy layer Ⅰ of poplar clone I-69and107was4years, and the more appropriatepruning season was the Spring.4. Moderate pruning was beneficial to improving the plumpness, growth of poplar trunk andaboveground biomass, the pruning scheme based on treatment Ⅱ was better for poplar clone I-69,likewise the pruning scheme based on treatment Ⅰwas better for poplar clone107.5. A new pruning way of poplar was invented successfully—pruning way according to theafforestation age and the status of whorled branches, with which the farmers can prune poplarbranches at a glance, whose operability is higher and popularization is easier.6. A set of scientific system of pruning techniques of poplar was summarized systematically.The conditions of pruned poplar stands, the initial pruning age, the pruning season, the pruningperiod and pruning intensity, the pruning quality and the pruning implements were positivelydemanded, which will provide with powerful support for cultivating high quality wood forplywood with high trunk, large plumpness and no knots.