Effects of drought stress on the growth, photosynthetic characteristics, and active oxygen metabolism of poplar seedlings. Transformation of BG2 Gene into Populus×euramericana cv.‘Neva’and Resistance of the Transgenic Poplar to Canker Disease Primary Study on Decomposition of Lignin of Poplar ‘I-107’by Trametes trogii WT-1 Effects of Stand Density on Growth of Populus×euramericana’Neva’ Plantations Microfibril Angle, Basic Density and Longitudinal Shrinkage of Different Inclined Angles in Artificial Leaned Saplings of Poplar ‘Ⅰ-107’(Populus× euramericana ‘Neva’)