EFFECTS OF DEFOLIATION, BUD REMOVAL AND GIRDLING TREATMENTS ON SPROUTING OF QUERCUS-ACUTISSIMA CARR

Effects of defoliation, bud removal and girdling treatments on sprouting in adult trees and seedlings of Quercus acutissima Carr. were investigated in order to clarify the mechanism of sprouting and the ecological significance of sprouts. Both in adult trees and seedlings, sprouts flushed below the positions of girdling. In seedling experiments, numerous sprouts also flushed in bud removal treatment. These results suggest that inhibitors of sprouting, formed in terminal or axillary buds, are translocated through phloem, thereby inhibiting sprouting from suppressed buds. In defoliation treatments, seedlings flushed new shoots from current axillary buds after treatment, although only a few sprouts flushed. As a consequence, a shortage of photosynthetic organs were not assumed to be directly related to sprouting. From these results, it is suggested that trees recover their assimilative architecture by flushing new shoots from current terminal or axillary buds when they lose foliage as a result of disturbance such as predation. On the other hand, sprouts flushed from suppressed buds are thought to contribute to the recovery of canopy caps or the maintenance of seedlings when the growth points on upper sections are lost due to disturbance. It is also suggested that differences in sprouting vigor caused by age, size and species should be discussed in relation to the balance between inhibition from terminal or axillary buds, and stimulation from lower parts of plants.