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Abstract

Poplar trees (Populus species and their hybrids) are commonly cultivated on agricultural land for their high biomass production during the first rotation. However, stand development during the long-term second rotation is less understood. This study evaluated the effects of a single thinning at age 7 on growth dynamics at both stand and dominant trees levels in a second rotation poplar plantation (clone OP42) in southern Sweden. Four treatments were applied: unthinned (6000 stems ha(-)1), light thinning (3000 stems ha(-)1), medium thinning (1100 stems ha(-)1), and heavy thinning (550 stems ha(-)1). Tree mortality, height, diameter, and stem volume/biomass were monitored over 11 years post-thinning. By age 18, the above ground volume/biomass at the stand level was primarily concentrated in trees with diameters greater than 21 cm. The standing volume/biomass of individual dominant tree ranged from 0.80 m3 (268 kg dry matter, DM) to 0.87 m3 (292 kg DM) in the medium and heavy thinnings, and from 0.64 m3 (214 kg DM) to 0.67 m3 (224 kg DM) in the unthinned and lightly thinned plots. The total stand-level volume/biomass production in unthinned and lightly thinned plots was maximized by an 18-year rotation, with the mean annual increment (MAI) culminating at 33 m3 ha-1 yr-1 (11 Mg DM ha-1 yr-1). In the medium thinning, MAI reached 38 m3 ha(-)1 yr(-)1 (12.7 Mg DM ha(-)1 yr(-)1) at age 18 and continued to increase thereafter, a trend also observed in the heavy thinning. For dominant trees, culmination of MAI had not yet occurred under any treatment.

Keywords

Poplar plantation; Second rotation; Dominant trees; Thinning effect; Growth; Biomass production

Published in

European Journal of Forest Research
2025
Publisher: SPRINGER

SLU Authors

UKÄ Subject classification

Forest Science

Publication identifier

  • DOI: https://doi.org/10.1007/s10342-025-01833-x

Permanent link to this page (URI)

https://res.slu.se/id/publ/144432