BIOMASS PRODUCTION AND ENERGY POTENTIAL OF SOME EASTERN COTTONWOOD (Populus deltoides Bartr. ex Marsh.) CLONES IN RELATION TO PLANTING SPACING

The possibility of biomass production was studied in an experimental trial stand with four clones of Eastern cottonwood Populus deltoides Bartr. ex Marsh, cl.457, cl.450, cl.618 and cl.55/65 and three stand densities a) 1.2 x 1.0 m (8330 plants times ha super(-1)), b) 1.2 x 0.75 m (11110 plants times ha super(-1)) and c) 1.2 x 0.5 m (16600 plants times ha super(-1)). Field trials were conducted on sandy-loamy form of fluvisol. Total determined volume of trunk, bark, and branches in the first two-year cycle for the used Eastern cottonwood ranged from 27.391 m super(3) times ha super(-1) in clone 450 at planting distance of 1.2 x 1.0 m, subtreatment (a) to 42.006 m super(3) times ha super(-1) in clone 618, subtreatment (c) at planting distance of 1.2 x 0.5 m. After renovation of stand using the regeneration force of shoots from the tree stumps the produced wood mass in the second two-year cycle ranged from 54.664 m super(3) times ha super(-1) in clone 55/65, subtreatment (a) to 79.235 m super(3) times ha super(-1) in clone 450, subtreatment (b). In additon to clone selection a significant influence on biomass yeald was also exerted by stand density (number of plants times ha super(-1)). The largest amount of heat energy would be obtained in subtreatment (c) at density of 1.20 x 0.5 m by combustion of biomass of above ground part of clone 55/65: 364.02 GJ times ha super(-1) in the first cycle, and 659.83 GJ times ha super(-1) in the second, or a total of 1023.85 GJ times ha super(-1).Original Abstract: U cilju iznalazenja najpovoljnije tehnologije proizvodnje biomase za energetske potrebe, istrazivanja su obavljena na Pokusnom dobru Instituta za nizijsko sumarstvo i zivotnu sredinu u neposrednoj blizini Novoga Sada u nasadima sa dvogodisnjim proizvodnim ciklusom, u poljskim uvjetima sa cetiri klona i tri razmaka sadnje u dva turnusa. Klonovi u pokusu pripadaju americkoj crnoj topoli (Populus deltoides Bartr. ex Marsh.): cl.457, cl.450, cl.618, cl.55/65. Razmaci sadnje su: (a) 1,20 x 1,00 m ili 8.330 biljaka times ha super(-1) (b) 1,20 x 0,75 m ili 11.110 biljaka times ha super(-1) i (c) 1,20 x 0,50 m ili 16.660 biljaka times ha super(-1). Zemljiste na kojemu su obavljena istrazivanja sustavno pripada tipu fluvisol, formi ilovastoj. Ovo zemljiste je cijelom dubinom karbonatno i oglejano, vrlo duboko, sa fizioloski aktivnom dubinom oko 200 cm. Morfoloska grada ovoga zemljista je A sub(mo, p)-IG sub(so)-IIG sub(so)-IIIG sub(so)-IVG sub(so)-G sub(r). Humusno akum