The population status of the Endangered endemic plant Aloe peglerae: Area of occupancy, population structure, and past population trends

Abstract

Aloe peglerae Schönland is a rare succulent plant species, which is endemic to South Africa. The species is currently listed as Endangered and is threatened mainly by illegal collection. The aim of this study was to determine the population status of Aloe peglerae in the Magaliesberg Mountain Range, that is, whether the population is declining, stable or increasing. Key population parameters assessed for this study included plant density, population structure, area of occupancy, population size, and rate of past population decline. Nine subpopulations were surveyed in 2009 and 2010 using a distance sampling technique. Also, these data were compared to data collected in 1999 by the Gauteng Department of Agriculture, Conservation and Environment, so as to determine possible population trends. The results showed a decline of 43% in mean population density between 1999 and 2010, suggesting that the population of Aloe peglerae in the Magaliesberg is in a state of decline. The application of this technique to plant populations is relatively novel and key recommendations are provided to improve survey design.