DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 3-4/2012 str. 52     <-- 52 -->        PDF

 
ability to resprout after multiple harvests; and feedstock uniformity. The idea of producing large amounts of wood biomass by the cultivation of fast growing tree species with different rotation periods is a well known approach of research at the Institute (Klašnja et al., 2002; 2002a, 2003, 2006; 2008; 2008a, 2008b, Orlović et al., 2003, 2004).
 
Material and methods
Materijali i metode
The research is done in three field trials situated in the North part of Serbia – Vojvodina Province. Vojvodina is distinguished by continental climate, and is marked by warm and rather dry summers, cold, severe winters and short transitional seasons (spring and autumn). Maximal temperatures in summer exceed 35 °C (to 38 and 39 °C), and absolute minimal ones decline to –25 °C (rarely to –30 °C). The highest amount of rainfall is in May and June (average 57 mm, 75 mm, respectively) while July and August are often very dry, (average 47 mm, 37 mm, respectively). In July and August, the monthly precipitation average is achieved in two to three days, and the periods without rainfall can be longer than two months. During spring (till May) low temperatures (even to –13 °C) might damage flowers and fruit set. Early autumn frost may also occur, though less frequently. Storm and hailstorm are regular phenomena from May until September, with highly irregular frequency.
Major characteristics of five poplar clones (4 clones belong taxonomically to Euramerican poplar and one to Eastern cottonwood) have been presented in Table 1.
Experimental plot 1: Experimental plot plantation was established by sprouting one shoot per stool after harvesting in the experimental estate "Kaćka šuma" (N 45°17’ 36,7", E 19°52’ 56,4"), with five experimental clones: four of Eastern cottonwood P. deltoides cl. ‘B-229’, cl. ‘B-81’, cl. ‘182/81’ and cl.’ PE 19/66’, and one clone of Euramerican poplar (P. × canadensis) cl. ‘Pannonia’, with 16667 plants ha–1. Experimental plantation was established on fluvisol – sandy soil. The main physical and chemical characteristics of the soil were determined by standard methods, based on which the soil was characterised as very favourable for poplar growing. The experiment was planted as a randomized complete block design with four blocks. Within the block each clone was planted once, in one row, with 50 plants. The spacing was 1.5 m between row and 0.40 m within plants in the row. Diameters and heights were measured on 20 plants per block.
Experimental plot 2: The trial was situated on the territory which is managed by Public Enterprise "Vojvodinašume" Forest Administration "Kupinovo", (N 44° 42’ 23.34", E 20° 01’ 59.63"), by planting one-year seedlings (1/1) on meadow brown soil on alluvial loess with 278 plants/ha. The experiment was planted as a randomized complete block design with four blocks. Within the block each clone was planted once, in one row, with 50 plants. The spacing was 6 m between row and 6 m between plants in the row. Diameters and heights were measured on 20 plants per block.
Experimental plot 3: The trial was situated on the territory which is managed by Public Enterprise "Vojvodinašume" Forest Administration "Višnjićevo", Management Unit "Banov Brod" 18a (N 44° 55’49.67", E 19° 22’57.61") on an area of 5.2 ha, by planting one-year seedlings (1/1) on alluvial semigley soil (humofluvisol), with 278 plants/ha. The experiment was planted in a randomized complete block design with four blocks. Within the block each clone was planted once, in one row, with 50 plants. The spacing was 6 m between row and 6 m between plants in the row. Diameters and heights were measured on 20 plants per block.
The plant diameters and heights were measured after the first and the second year (plants as stump shoots – Experimental plot 1), and after seventh growing season (plants in the plantation established by one-year seedlings – Experimental plots 2 and 3).
Biomass volume per unit area was calculated, as well as volume increment, and biomass weight (aboveground biomass weight, without leaves) was determined based on wood density of the analysed clones.