Mixed, short rotation culture of red alder and black cottonwood: growth, coppicing, nitrogen fixation, and allelopathy

Journal Article · Tue Jan 01 04:00:00 EST 1985 · For. Sci.; (United States)

OSTI ID:5259478

Heilman, P; Stettler, R F

Alnus rubra seedlings were grown in a 1:1 mixture at a spacing of 1.2 x 1.2 m with 28 Populus clones (25 clones pf P. trichocarpa, 2 of P. deltoides x P. trichocarpa, and one P. deltoides x P. nigra) in a study established in W. Washington in March 1979. Trees were harvested at 4 yr old. At harvest, average heights were: pure Populus, 10.2 m; Populus in the mixed stand 11.0 m; and alder 8.4 m. Most Populus sprouted satisfactorily after harvest (6.6 shoots/plant when pure, 7.6 shoots/plant in the mixture), but alder sprouted poorly (3.6 shoots/plant). Above-ground biomass at harvest was 15.9 t/ha p.a. for the mixture and 16.7 t/ha p.a. for pure Populus, although the mixture had been more productive at 2 yr. Nitrogenase activity (nitrogen fixation as measured by acetylene reduction) of alder declines in the 4th season; competition was the most important factor influencing this decline. Soil N content had no effect on fixation. A pot study showed that ground Populus leaf and litter material inhibited the growth of red alder seedlings, although soil collected from Populus plots had no effect. Results indicated that allelopathy is probably a minor factor under field conditions, at most, and that growing mixed stands may, on balance, be beneficial. 20 references.

• Research Organization: Washington Research and Ext Center, Puyallup
• OSTI ID: 5259478
• Journal Information: For. Sci.; (United States), Journal Name: For. Sci.; (United States) Vol. 31:3; ISSN FOSCA
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
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BIOMASS PLANTATIONS
COTTONWOODS
CULTIVATION TECHNIQUES
ENZYME ACTIVITY
ENZYMES
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NITROGEN FIXATION
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