Abstract
Euphorbia clivicola R.A. Dyer is a Critically Endangered Northern Province endemic confined to two populations that have declined drastically over the last decade. One population is protected within a Nature Reserve, while the other occurs in a peri-urban area. In order to determine the causes of the population declines, herbivory damage to plants in both the protected and urban populations was quantified and the effects of herbivory on various aspects of the population biology were assessed. Mountain reedbuck are believed to have been responsible for the herbivory in the protected population. Herbivory on the above-ground branches probably caused the small sizes of protected plants. These were on average less than half the size of urban plants. Herbivory caused a reduction in the number of flowers and fruit produced per protected plant and may have prevented the maturation of flowers into fruit, thereby reducing the total regenerative output of the population. An eight-year absence of fire had resulted in the build-up of a dense moribund grass layer. The selection of E. clivicola plants by mountain reedbuck may therefore have been due to their relatively high nutritional value and accessibility in the thick moribund grass layer. Fencing off the population to prevent entry of herbivores, and implementing a more suitable fire management programme is recommended, as is the adoption of a new IUCN status for the species of Critically Endangered (CR A1).
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Pfab, M., Witkowski, E. Contrasting effects of herbivory on plant size and reproductive performance in two populations of the Critically Endangered species, Euphorbia clivicola R. A. Dyer. Plant Ecology 145, 317–325 (1999). https://doi.org/10.1023/A:1009869011237
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DOI: https://doi.org/10.1023/A:1009869011237