Catastrophic disturbance, logging and the ecology of mahogany (Swietenia macrophylla King): grounds for listing a major tropical timber species in CITES

Abstract

Recent debate on whether or not mahogany (Swietenia macrophylla King) isthreatened by the international timber trade has focused on the breadthof its range and estimates of the remaining stock of mahogany trees.These data are inadequate to reveal the status of mahogany populations,both because they are incomplete in areal extent and because they do notreveal population parameters such as the existence or density of youngtrees smaller than commercial size. However, there is sufficientinformation on the regeneration ecology of mahogany to indicate thatunder natural conditions this species regenerates in essentiallyeven-aged stands after catastrophic disturbances destroy many or mosttrees, and, in the case of fires and flooding, saplings and seedlings aswell. Adult mahoganies tend to survive these events, and regenerate byshedding seed onto the resulting gaps or clearings. This ecologicalstrategy makes mahogany vulnerable to logging, first because juvenilemahoganies are not found in the understorey, and secondly becauselogging operations shortcircuit mahogany regeneration processes byselectively removing almost all mahogany seed sources while leavingstanding competing vegetation of other species. Listing of mahogany inCITES Appendix II could provide both a mechanism to fill in gaps ininformation and an incentive to change current practices in favour ofsilvicultural management to provide for regeneration of this valuabletimber species in forest subjected to logging. (C) 1996 The LinneanSociety of London