DIGITALNA ARHIVA ŠUMARSKOG LISTA
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This trait should be taken into consideration while selecting clones for stand establishment for biomas production in short rotations and their restoration using regeneration force of shoots from tree stumps after felling. 4. Conclusions Zaključci The results of the presented research of two two-year cycles suggested that technology of dense planting of Eastern cottonwood (Populus deltoides Bartr. ex Marsh.) on fluvisol soil is one of the realistically possible ways for producing poplar wood intended for energy purposes. The weight of biomass was estimated based on produced volume and value of the volume mass of wood. At the end of first two-year cycle, stand established with cuttings, the weight of biomass ranged from 10.35 t·ha–1 in clone 618 at density of (1.2 × 1.0 m) to 18.68 t·ha–1 in clone 55/65 at density of (1.2 × 0.5 m). Due to the regeneration force of shoots from tree stumps the weight of biomass in the second cycle ranged from 22.54 t·ha–1 in clone 618 at density of (1.2 × 1,0 m) to 33.86 t·ha–1 in clone 55/65 at density of (1.2 × 0.5 m). When establishing stands of this type, special attention should be pied to selection of clones and planting density on appropriate soil (habitat). Advantage should be given to clones with rapid growth in the juvenile stage of development and genetic traits of regeneration of stumps after felling, which enables restoration of stands using shoots from stumps in several cycles. The greatest amount of heating energy of 364,02 GJ·ha–1would be obtained in subtreatment (c) at density of 1.2 × 0.5 m by combustion of biomass of the above ground part of clone 55/65 in the first cycle, and 659.83 GJ·ha–1 in the second or the total of 1023.85 GJ·ha–1, Within the group of tested clones of Eastern cottonwood (Populus deltoides Bartr. ex Marsh.) the minimum quantity of heating energy of 202,38 GJ·ha–1 would be provided in subtreatment (a) at density of 1.2 × 1.0 m by combustion of above ground part of biomass in clone 618 in the first cycle, and 440.75 GJ·ha–1 in the second, or the total of 643.13 GJ·ha–1. By introducing into production the clones of Eastern cottonwood (Populus deltoides Bartr. ex Marsh.), which were selected for chosen characteristics, a significant influence could be exerted on biomass yield per area unit in short cycles. Combined with proper choice of clones at appropriate planting density and duration of production cycle, and with necessary care measures all needed prerequisites for a successful establishment of plantations for energy production (so called "energetic plantations") from renewable natural sources could be achieved. Acknowledgments Zahvala This paper was realized as a part of the project "Studying climate change and its influence on the environment: impacts, adaptation and mitigation" (43007) financed by the Ministry of Education and Science of the Republic of Serbia within the framework of integrated and interdisciplinary research for the period 2011–2014. 5. REFERENCES Literatura Andrašev, S., Rončević, S., Ivanišević, P. (2003): Proizvodnja repromaterijala selekcionisanih klonova crnih topola (sekcija Aigeiros Duby) u zavisnosti od klona i razmaka sadnje u ožilištu. Topola 171/172: 3–24. Benetka, V., Bartakova, I., Motti, J.(2002): Productivity of Populus nigra L., spp nigra under short-rotation culture in marginal arsas. Biomass and Bioenergy 23: 327–336. Ciria MP, Mazon P., Carrasco J., Fernandez J., (1995): Effect of rotation age on the productivity of poplar grown at higt plantation |