TAILIEUCHUNG - Báo cáo lâm nghiệp:"Long-term effects of vegetation control treatments for release of Engelmann spruce from a mixed-shrub"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài:"Long-term effects of vegetation control treatments for release of Engelmann spruce from a mixed-shrub" | 681 Ann. For. Sci. 60 2003 681-690 INRA EDP Sciences 2004 DOI forest 2003062 Original article Long-term effects of vegetation control treatments for release of Engelmann spruce from a mixed-shrub community in Southern British Columbia Balvinder Singh BIRINGa Philip George COMEAUb Peter FIELDERa a British Columbia Ministry of Forests Research Branch PO Box 9519 Stn. Prov. Gov. Victoria . Canada V8W 9C2 b Department of Renewable Resources University of Alberta 4-42 Earth Sciences Building Edmonton Alberta Canada T6G 2E3 Received 24 June 2002 accepted 19 February 2003 Abstract - In British Columbia vegetation management treatments are widely used to ensure successful establishment of young stands and achievement of free-growing requirements. A study was established in 1991 to examine the effectiveness of vegetation control treatments for release of Engelmann spruce Picea engelmannii Parry seedlings from a mixed-shrub community. The study consisted of eight treatments replicated three times in a completely randomized design. The treatments comprised six combinations of spring summer and annual repeated manual cutting a single application of glyphosate and an untreated control. Controlling the mixed-shrub community one-year after planting using glyphosate and manual cutting treatments significantly improved spruce survival. Repeated manual cutting significantly improved survival over that achieved with only a single treatment. Consequently the density of well-spaced trees was significantly increased in the repeated manual cutting and glyphosate treatments. In 2001 the untreated control only has 27 of well-spaced spruce trees that are free growing compared to more than 50 75 and 83 in single cutting repeated manual cutting and glyphosate treatment respectively. Treatments significantly increased height and groundline diameter from the third through the seventh year but not in year ten. Continued mortality of suppressed seedlings after year seven is a probable

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