Factors that contribute to basal sweep in lodgepole pine.

Abstract

An increase in the presence of basal sweep in lodgepole pine (Pinus contorta Douglas ex Loud.) crops has occurred in recent years following wide scale planting of vigorous coastal provenances from Washington and Oregon. The attributes of low nutrient requirements and tolerance of severe exposure makes these provenances ideal pioneer crops for difficult sites, but the high incidence of sweep on exposed areas causes difficulties in both the harvesting and conversion of the timber. Despite extensive experimentation the problem of basal sweep has not been fully resolved. This has resulted in the favouring of lower yielding but straighter provenances or alternative species. In some cases these options may not be economic due either to inherent slow growth rate or the necessity for increased fertiliser inputs. The reduction or elimination of basal sweep in the south coastal provenances would therefore increase the profitabilty of growing timber on these difficult sites...