Browsing by Author "Warwick B. Silvester"

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    Nitrogen fixation and acetylene reduction in decaying conifer boles: effects of incubation time, aeration, and moisture content
    (2007) Warwick B. Silvester; Phillip Sollins; Thomas Verhoeven; Steven P. Cline
    Nitrogen fixation and acetylene reduction in decaying conifer boles: effects of incubation time, aeration, and moisture content. Can. J. For. Res. 12: 646—652. Free-living microaerophiles fixed 15N2 and reduced acetylene in fallen tree boles at two old-growth Pseudotsuga menziesii stands in western Oregon. Acetylene reduction was most rapid under an atmosphere of 2—10% O2, whereas under prolonged anaerobic conditions it was at or below detection limits. Acetylene reduction rates increased up to fourfold during long-term incubations in acetylene (> 12 h). Ratios of acetylene reduction to N2 fixation frequently exceeded 6.0 during such long-term incubations but averaged 3.5 when samples were incubated < 7 h; consequently, long-term incubation of low-activity material in acetylene should be avoided. A preliminary survey indicated that N2 fixation by free-living organisms in fallen boles was less than other potential N inputs to fallen boles and to the forest ecosystem.