The control of Stoebe vulgaris encroachment in the Hartbeesfontein area of the North West Province

Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2008.

This project forms the research component of a larger LandCare program where farms in the Hartbeesfontein area of the North West Province were targeted for the eradication of Seriphium plumosum (previously known as Stoebe vulgaris). The research was done to give more insight into the population demography of S. plumosum, to obtain baseline data to monitor the effect of different control technologies on S. plumosum densities and grass species composition, as well as to make certain recommendations with regard to the control of S. plumosum encroachment. With regard to the population demography of S. plumosum, it was determined that the period of active growth is from August to early March. The reproductive phase of S. plumosum lasts from December to the end of May. This implies that control should be done before the reproductive period to prevent seeds from being dropped. The results obtained from the study sites in the Hartbeesfontein area before chemical control of S. plumosum was done showed that encroachment could occur in veld in a good condition and in degraded veld if the habitat conditions are suitable for the encroachment. This was established from the soil sample analyses which indicated that rocky, sandy soils are prone to encroachment. Old crop lands are especially prone to S. plumosum encroachment due to the lack of competition by grass species. The different control technologies used were chemical control, fire and manual clearing of the shrub. The results showed that chemical control of the shrub is the most effective control technique, while burning and manual clearing of the shrub led to higher densities if not properly managed. Irrespective of the control technology used, it is important to have a follow-up control program as well as a sound veld management plan to prevent the re-encroachment of the shrub.

Masters