Response of loblolly pine plantations to woody and herbaceous control--eighth-year results of the region-wide study - the comproject

摘要

Eight-year response of planted loblolly pine to woody and herbaceous control following site preparation, studied at 13 locations, differed by pine response variable and hardwood level grouping. Treatments affected average pine height the same at both low hardwood (<6 ft~2/ac basal area at age 8) and high hardwood (>13 ft~2/ac) levels, and ranked: total control (woody + herb control) > herb control only > woody control only > no control. The same ranking held for pine dbh, basal area/ac, and volumeindex/ac at the low hardwood level. However, at the high hardwood level, dbh response from woody control only exceeded that for herb control only, while basal area/ac and volume index/ac response were equal for the two treatments. Volume index increasesover no control on the low and high hardwood levels averaged 127 percent and 336 percent greater with total control; 32 percent and 57 percent greater with woody control only; and 92 percent and 73 percent with herb control only, respectively. Treatmenteffects on all pine response variables were additive at the low hardwood level, and more than additive at the high hardwood level.