Productivity and biomass partitioning in 20-year Black cottonwood at variable spacing

• Main Author: Lena Mikaelsson 1984-
• Other Authors: Landbúnaðarháskóli Íslands
• Format: Thesis
• Language: English
• Published: 2011
• Subjects: Iceland
• Online Access: http://hdl.handle.net/1946/9258

The main objectives of this study were to investigate the effects of different spacing treatments on aboveground biomass production, bark, sapwood and heartwood ratios and the branching ratio in 20-year old Black cottonwood (Populus balsamifera L. ssp. trichocarpa (Torr. & A. Gray ex Hook.) Brayshaw) experimental plantation within Sandlækjarmýri research forest in southern Iceland. Data and wood samples were collected from 40 trees of 8 different spacing treatments (0.5 x 0.5 m, 0.5 x 1.0 m, 1.0 x 1.0 m, 1.0 x 1.5 m, 1.0 x 2.0, 2.0 x 1.5 m, 2.0 x 2.0 m and 3.0 x 3.0 m) repeated five times in a random manner. Main findings were that overall aboveground biomass per hectare increased with density and reached carrying capacity at approximately 5 000 trees ha-1. Density effects on survival and bark, sapwood and heartwood ratios were insignificant between spacing treatments. Initial spacing, however, did have significant effect on the ratio of branch mass to total above ground biomass that decreased with increasing density.