CROWN EFFICIENCY OF OAK STANDARDS AS AFFECTED BY MISTLETOE AND COPPICE REMOVAL

Effects of mistletoe (Loranthus europaeus Jacq.) and coppice removal on the efficiency of crown projection area and the growth of sessile oak (Quercus petraea Liebl. ) standards were studied in a 2 x 2 factorial experiment with nine replications. Four treatments were applied in 1980: control, coppice removal only, mistletoe removal only and removal of both coppice and mistletoe. After 11 years, the basal area increment, the crown efficiency (basal area increment per square metre of crown projection area) and the crown projection area increment showed statistically significant interactions between initial crown size, coppice removal and mistletoe removal. The basal area increment increased strongly with increasing crown size, but crown efficiency was maintained at the same low threshold for all crown sizes when the coppice remained, regardless of whether mistletoe was removed or not. This constant crown efficiency may be attributed to a decrease in crown projection area of larger trees rather than to higher increments. The effect of coppice removal was highest for small crowns and was independent of mistletoe removal. For larger crowns, the effect of coppice removal was much more pronounced when mistletoe was also removed.