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ŠUMARSKI LIST 3-4/2012 str. 51     <-- 51 -->        PDF

ENERGY POTENTIAL OF POPLAR PLANTATIONS IN TWO SPACINGS AND TWO ROTATIONS
ENERGETSKI POTENCIJAL NASADA TOPOLA SA DVA RAZMAKA SADNJE I DVIJE DUŽINE OPHODNJE
Bojana Klašnja, Saša Orlović, Zoran Galić1
Summary

The article presents the results which are related to the biomass yield of five poplar clones in the testing phase: P. deltoides cl. ‘B-229’, P. deltoides cl. ’B-81’, P. deltoides cl. ‘182/81’, P. deltoides cl. ‘PE 19/66’, and Euramerican poplar P. × canadensis cl. ‘Pannonia’, in experimental plantations of seven years, with planting space of 6×6 m (278 plants ha–1) on two soil types. Also, the analysis of the biomass yield of the same clones that were established as dense plantations, by sprouting one shoot per stool after harvesting in the experimental plot at the Institute with the planting space 16667 plants ha–1 (1.5 m between rows and 0.4 m within rows). The energy that could be obtained by biomass combustion, on base of wood calorific values for the examined clones has been estimated. It was found that the maximum (annual) weight of biomass, and thus also the energy in SRF plantations, are obtained by the clone ‘PE 19/66’ – 7.236 tha–1, and 134.556 GJha–1, respectively. However, clone ‘B81’, which achieves the maximum values in the SRC plantations (6.617 tha–1 and 121.523 GJha–1), has the least oscillations in all experiments and is very close to maximum values in SRF plantations.

Key words: poplar clones, spacing, biomass yield, energy
 
Introduction
Uvod
To mitigate climatic change caused by greenhouse gas emissions, the developed world is working to substitute fossil fuels with renewable energy sources. Short rotation forestry (SRF), i.e. fast-growing tree crops grown in carefully tended plantations for rotations shorter than 15 years have an important role to play, because of their numerous ecological benefits. This special type of forestry is concerned with maximization of wood biomass output per hectare for energy production. High­ly productive pioneer species are willow and poplar species as a short rotation coppice (SRC) system. It is assumed that for the SRC system the first harvest takes place after 5 years and subsequently every three years up to an age of 20–25 years (willows), and for poplars 7–10 year rotations apply. Fertilization, annual weeding and mechanical harvesting are assumed. The density of SRC systems is assumed 9000–10000 stools per hectare (Laureysens et al., 2005). The SRIC system (short-rotation intensive culture) as applied in this context involves the establishment of plantations using genetically improved, clonally propagated, plant materials (i.e. willow and poplar species) at a density of ~15000 plants ha−1, which are coppiced at the end of the first year and then managed on a three-year rotation (Tharakan et al., 2003). The biomass produced from short rotation coppice (SRC), such as willow and poplar, may have a number of uses: as a fuel for electricity generation plants; for the production of charcoal; as a soil amendment for clay caps; or simply as a carbon sink for atmospheric CO2.
Poplars, which are the focus of this paper, have several characteristics that make them ideal for SRC systems, including high yields that can be obtained in a few years; case of vegetative propagation; a broad genetic base; a short breeding cycle;
 

1 Dr Bojana Klašnja, dr Saša Orlović, Dr Zoran Galić, University of Novi Sad, Institute of Lowland Forestry and Environment, Antona Cehova 13, 21000 Novi Sad, Serbia, email: bklasnja@uns.ac.rs