Abstract: The effect of tree crown disposition on the vertical distribution of annual increment in the main stem of Populus deltoides Bartr. cv. "Lux"ex. 1-69/55 was studied by measurement at fixed position in 1985-1986. The tend of distribution of annual increment inside plantation was different from outside. The increment of main stem under branches of the latter was more than the former. The maximum increment of stem diameter was at bottom, diminished up to branch height, then increased to crown. With increase of pruning height, the volume increment of crown stem became greater than the below stem. Cross-section area of lateral branch increased 1cm², the difference between upper and below section areas at the positions of growing branch was about 0.7cm². Pruning is important for reguiation of increment in main stem.

Key words: Crown disposition, Pruning, Volume increment