DETERMINING PAST AND FUTURE POPULATION TRENDS IN THE THREATENED ENDEMIC PLANT ALOE PEGLERAE

 

Justin Phama, Michèle Pfab, Michael Panagos and Willem Myburgh

Tshwane University of Technology

 

Abstract: Aloe peglerae Schönland is a Rare and Endangered succulent plant species, in the family Aloaceae. The species is endemic to South Africa and occurs only in the Gauteng and North West provinces. To determine the population status of A. peglerae, nine subpopulations surveyed in 1999 were relocated and resurveyed in 2009 and 2010 using a distance sampling technique. A stochastic population projection model was then used to quantitatively assess future population trends, assess the viability of the nine A. peglerae subpopulations, and also to determine extinction-risk thresholds under varying harvesting scenarios. Overall, the population showed a statistically significant decline of 43% in mean population density between 1999 and 2010. Moreover, the results clearly showed the cumulative negative impact of illegal and uncontrolled plant collection. The increase in the level of population exploitation resulted in a corresponding increase in the probability of extinction of a subpopulation. Key recommendations are made in implementing cost-effective sampling techniques for long-term monitoring and in using modelling tools in determining optimum levels of harvest for sustainable use of species.

 

Presentation Topic:

DETERMINING PAST AND FUTURE POPULATION TRENDS IN THE THREATENED ENDEMIC PLANT ALOE PEGLERAE

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