A QUANTIFICATION OF SHOOT SHEDDING IN PEDUNCLATE OAK (QUERCUS-ROBUR L.)

Almost 37 000 fragments (twigs, peduncles, inflorescences) were shed f rom a single mature oak tree over one year. Shedding showed strong sea sonality with abrupt peaks in June and October, yet only weak correlat ions to weather parameters. The majority of shed twigs were short shoo ts, consisting of one or few extension units, which were not older tha n two years. In many twigs, shedding was preceded by the outgrowth of the terminal bud into either a male inflorescence or a defective exten sion unit. The large majority of shed twigs belong to a male category of summer annual and biannual deciduous short shoots of an exploitativ e nature, only a minority are explorative long shoots. Implications fo r the architecture of the tree crown are that twigs of higher branchin g order are mostly affected by shedding, as they consist of short modu les which exhibit a high proportion of flower buds. (C) 1998 The Linne an Society of London.