Document Type : Research article
Authors
1
Corresponding author, Associate Prof., Research Institute of Forests and Rangelands, Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran
2
Senior Research Expert, Research Institute of Forests and Rangelands, Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran
3
Assistant Prof., Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, Iran
Abstract
Background and objectives: Poplar trees are considered as important resources in wood production, which plays an important role in supplying wood raw materials for wood and paper industries, as well reducing the pressure on the natural forests. This study aims are to evaluate the wood production performance of exotic clones of eastern cottonwood (Populus deltoides W.Bartram ex Marshall) and its hybrids (P. x canadensis Moench) clones, which were imported into Iran in the early 2000 and were experimented in the climatic conditions of Alborz province for five years.
Methodology: The research was conducted at the Alborz Research Station, Karaj County, on 11 exotic poplar clones of P. deltoides and its hybrids, along with three successful poplar clones introduced in Alborz province as controls. For each clone, 27 one-year-old saplings were planted, totaling 378 main saplings with an additional 194 non-experimental boundary trees to assess border effects. The experiment followed a completely randomized block design with three replications. Saplings were spaced at 3×4 m². Furrow irrigation was applied weekly, and weed control was maintained regularly. Annually, at dormancy, growth parameters including survival rate, diameter at breast height (DBH), and height were measured for all trees. Stand volume and current annual increment were calculated, along with average volume per hectare and the slenderness coefficient for each clone. Two-way ANOVA analyzed the data, with Duncan’s multiple range test used for mean comparisons.
Results: Variance analysis after five years showed significant differences among clones in DBH, height, volume, and stand volume per hectare, except for survival percentage. The mean annual volume increment and total volume at year five highlighted two clones, P. x canadensis Pacher and P. deltoides Marquette, with the highest wood production at 8.21 and 7.27 m³·ha⁻¹·year⁻¹ and total volumes of 41.05 and 36.33 m³·ha⁻¹, respectively. Two clones, P. deltoides 92/258 and P. x canadensis 92/40, ranked second in performance. The slenderness coefficient among clones ranged from 63 to 74, with the highest values in P. x interamericana and P. deltoides 92/258 (73.6 and 71.2), and the lowest in P. x canadensis BL Costanzo (62.8).
Conclusion: Genetic diversity and local climatic conditions significantly influence the selection of successful poplar clones regarding growth and wood productivity. In this study, P. x canadensis Pacher demonstrated the highest average current annual increment in DBH (2.22 cm) and stand volume (8.21 m³·ha⁻¹) compared to the control clones (P. x canadensis I-488 and P. x canadensis 92/40). Therefore, in semi-arid regions, this clone is recommended as a successful option for wood production.
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