tailieunhanh - Báo cáo lâm nghiệp: "Eighth-year response of Douglas-fir seedlings to area of weed control and herbaceous versus woody weed control"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: "Eighth-year response of Douglas-fir seedlings to area of weed control and herbaceous versus woody weed control" | Ann. For. Sci. 62 2005 481-492 481 INRA EDP Sciences 2005 DOI forest 2005053 Original article Eighth-year response of Douglas-fir seedlings to area of weed control and herbaceous versus woody weed control Robin Rose Lee Rosner Department of Forest Science Oregon State University 321 Richardson Hall Corvallis OR 97331-5752 USA Received 21 July 2004 accepted 28 January 2005 Abstract - Coastal Douglas-fir growth response to eight experimental weed control treatments has been followed for eight years since planting at two western Oregon sites. Treatments included six areas of weed control around individual trees - 2 m2 m2 m2 m2 and m2 total vegetation control TVC - control of herbaceous competition only or control of woody competition only. Herbaceous vegetation control treatments were maintained for the first two years after planting while woody vegetation control treatments were maintained for three years. The greatest gain in Douglas-fir growth from increasing the area of control was observed between the m2 and the m2 treatments. Growth continued to increase however with increasing area of control out to complete weed control. The m2 and m2 treatments increased eighth-year individual-tree volume relative to the check treatment by 260 dm3 and 307 dm3 respectively. While herbaceous control increased growth at both sites woody control affected growth only at the site having the hardwood component with greater height growth potential. Growth differences among treatments eight years after planting are discussed in terms of distance to competition and shifting dominance from herbaceous to woody vegetation over time. vegetation management herbaceous competition woody competition area of weed control herbicides Résumé - Impact de la surface désherbée et d un contrôle de la végétation herbacée ou de la végétation ligneuse sur la croissance de jeunes sapins de Douglas âgés de huit ans. La réponse en termes