Mortality in the Flowers, Fruits and Young Regeneration of Trees in the Knysna Forests of South Africa

Insufficient importance is attributed to mortality in studies of plant distribution and succession. Indeed, as one ecologist has remarked in the course of correspondence with the writer, one is almost accused of having a morbid mind if one emphasizes the need for investigation of the factors responsible for mortality in plants. Some pass the matter lightly by, others do not even remember its existence. In South Africa attention has been directed to the subject, in passing, by flews ('20, p. 450) and Schonland ('24, p. 456), while in America Clements ('i6, pp. 58-6o) has kept it in mind. The work of Watt ('I9, 23) in Britain has been particularly valuable. On reviewing the results of various ecological experiments in the indigenous forests of the Knysna region, the writer has been forced to the conclusion that much light is likely to be cast upon various problems in plant sociology by means of a thorough investigation of the agencies responsible for death, and of the amount and rate of death for which they are responsible. It is thought that a general account of the results of some studies being carried out by the writer may set forth certain points of interest and of importance. The mortality is greatest in the flowers, fruits and young regeneration, and in this communication attention is confined to a review of the factors causing death in these stages of ten of the more important tree species in the Knysna forests. Such factors are the following