Niche requirements and breeding system of Hypericum pseudohenryi, an invasive plant species in South Africa.

Abstract

Invasive alien species threaten ecosystems throughout South Africa through alteration of the habitat and loss of biodiversity. Emerging invasive alien plants are those that have small populations, but have the potential to spread and cause widespread damage in the future. One of these emerging invasive alien plants, Hypericum pseudohenryi, came from China as an ornamental plant, and has invaded the KwaZulu-Natal Drakensberg and Midlands and mountains of the Eastern Cape. There is little published information about H. pseudohenryi, both in the native range and the invaded range. To help create better management plans for H. pseudohenryi in the future, experiments were done to determine whether the species is self-compatible and to determine the potential spread of the species across South Africa. Breeding system experiments found that H. pseudohenryi is self-compatible and is able to produce small numbers of seeds via autogamous self-fertilisation. This indicates that there is a high risk of new populations being formed from a single founder individual. Climate niche modelling using current climatic conditions revealed that H. pseudohenryi has not yet realised its full climatic niche in South Africa. As the climate changes in the future, climate niche modelling showed that the range of climatically suitable habitat of H. pseudohenryi is contracting into high altitude areas of the Drakensberg. These findings suggest that H. pseudohenryi requires intense management, especially in the Drakensberg area, to contain the spread of this emerging invasive species.