Is the collection of Aloe peglerae from the wild sustainable? An evaluation using stochastic population modelling

Aloe peglerae Schönland, an Endangered species endemic to South Africa, is threatened mainly by illegal collection. Lower densities of plants in areas easily accessible to the public led to questions concerning the sensitivity of this species to collection. Demographic monitoring data collected between 1976 and 1995 were used to build a stochastic population model, where parameters were allowed to vary randomly between observed minimum and maximum values. The model indicated that A. peglerae is highly sensitive to harvest of adult plants, with use sustainable at only very low levels of not more than 0.12%. Harvesting one plant annually is only sustainable in large populations of more than 1000 individuals; populations of this size, however, are rare. A maximum of fifteen percent of the annual seed output can be harvested sustainably. This long-term evaluation demonstrates that current collection of this species from the wild is unsustainable. Ex situ cultivation is therefore vital.