Alien plant invasions and human-induced land transformations are the two most important factors contributing to loss of biodiversity, and Chromolaena odorata (C. odorata) is one of the world’s worst invader plants. It impacts negatively on biodiversity conservation, forestry and agriculture due to its rapid rate of spread, fast growth and hence an ability to transform habitats. It was introduced into KwaZulu-Natal, South Africa in the mid-1940s, and has spread north and southwards along the coastline and adjacent interior. In 1961 it was observed in Hluhluwe Game Reserve, and has invaded and transformed large parts. In this thesis I use C. odorata distribution maps from 1978 to 2001 to investigate invasion pathways, and whether these are related to species or habitat characteristics. Invasion in the twelve vegetation types identified in the Reserve showed two patterns. In some vegetation types invasion expanded linearly, while in others there were three phases of invasion, driven by interactions between habitat suitability, habitat fragmentation and propagule pressure. Expansion of existing invasions (phalanx or wave invasion) through short distance seed dispersal was the primary mode of spread, rather than the formation of new infestations (guerrilla or diffuse invasion). Known distribution of dense stands was used to develop a spectral signature and run a supervised classification of satellite images. I utilized the dense stands and other GIS data sets of climate, altitude, solar radiation, distance from roads, distance from rivers and normalized differential vegetation index from 1973 and 2001 to determine a probability model, and assess the impact of the invasion on biodiversity conservation. The supervised classification underestimated the extent of the invasion, as C. odorata is a cryptic understory species in some habitats. Supplementation by using multiple regression to develop a probability model, and combining these into one map provided a realistic result. I used this map and GIS data sets of vegetation types and protected areas to assess the impact of the invasion on biodiversity conservation. This showed that C. odorata was preferentially impacting sensitive areas, and the conservation of threatened vegetation types is not guaranteed by including them in protected areas. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2009.

According to Baker (1955), success of plant invasions can be attributed to autogamous breeding systems and generalist pollination systems. A test of Baker's rule was carried out on 19 invasive alien plant species in KwaZulu-Natal, South Africa. Natural levels of fruit set in these plants was high (median= 71.5% fruit set per plant). Breeding system experiments for 18 species showed that 17% of the species are allogamous, 72 % are autogamous and 11% are apomictic. This contrasts markedly with a general flora of 1472 species in which 65% are allogamous, only 14% are autogamous, and 21% are apomictic. Because the breeding systems of the alien species were largely autogamous, pollinators make only a small contribution to the overall reproductive success. Seventy one percent of the 14 alien species for which pollinators were obtained were pollinated by honeybees, which are super-generalists and ubiquitous in a generalist pollination systems. However, some species showed pre-adaptation to relatively specialized pollination systems, involving hawkmoths, butterflies and Xylocopa bees respectively. Thus, alien plants were not visited by a wide range of insects, but rather showed pre-adaption to one or more pre-existing guilds in the new habitat. Pollen limitation experiments showed no evidence that reproductive success in populations of the species is limited by pollen availability. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

The eMpofana riparian rehabilitation project (eMRRP) is a pilot project started by Umgeni Water (UW) to demonstrate how effective the removal of invasive alien vegetation is in improving the water yield of a catchment. The disturbance of the country's vulnerable wetland and riparian zones is a major factor contributing to water· stress. The study area was eMpofana riparian areas of Kwazulu-Natal midlands. The study was conducted to establish perceptions of property owners and project employees on eMpofana riparian rehabilitation project with regard to control of invasive alien vegetation. Apart from· these two categories of stakeholders, others whose perceptions were included in the study are one official each from MONDI, SAPPI, the National Working for Water Programme (WFWP) and Kwazulu Natal Nature Conservation Services. However, property owners and project employees were· the main respondents of study. Although all .stakeholders play a crucial role in the project, property owners were selected because clearing takes place on their properties. Similarly project employees perceptions were vital as they are physically involved in clearing invader species and are direct beneficiaries of the project through job creation; To enable interviewees to give their perceptions on various steps on the project cycle; the following key issues were selected; Awareness, Process, Water, Biodiversity, . Tourism, Capacity building, Support, and Sustainability of control of alien invasive plants. Based on these key issues, a questionnaire was drawn. There were fifty-two respondents: 25 property owners and 27 project employees.. The approach used in the study was survey research, and social science methods were employed. Survey research was chosen for this research because of its capacity to provide appropriate data on perceptions of stakeholders of the eMpofana project. The method is useful in a variety of situations such as providing solution to a problem of public policy, provide required data for managing a business or simply for testing hypotheses developed by scientists in the social world. The questions on awareness of the eMpofana riparian rehabilitation project (eMRRP). and the National Working for Water Programme{WFWP) revealed low awareness levels of the two projects. Almost half (48%) property owners indicated little awareness of the national WFWP and almost the same percentage i.e. 42% had little awareness of the provincial WFWP. Also 96% of eMpofana project employees indicated no awareness of the WFW national level and 70% said they were not aware of the WFW provincial level. Given that WFW is a national programme with over 200 alien plant control progratmhes countrywide, one wonder why awareness was so low among the respondents. As for involvement in the project conceptualisation, none of the respondents interviewed indicated involvement in that project phase. However all the project employees indicated that the project was successful (85% very successful and 15% successful). Fifty six per cent property ~wners indicated very strong 'support mainlybecause ofreestablishment of biodiversity through ridding the riparian areas of iilvader species. Ninety-five per cent of the project workers indicated that UW solely supports the eMpofana project and that that support is mainly financial. As for job creation, 88% project workers were of the view that eMpofana riparian project was very successful in creating jobs. It is worth noting that both property owners and the employees shared the same view on water users and project employees being the main beneficiaries of the project. The impact of clearing invader species oil water by the eMRRP was rated as being very significant. Moreover, 52% employees and 44% property owners felt that the project's main beneficiaries were water users in the cities and property owners themselves. As for linkage with the National WFW programme, the perceptions of property owners and project employees revealed a general preference for eMpofana project to continue running independently. On. succesSes achieved in various project phases, most property owners felt the planning phase of the project was the most successful, even though most of them were not involved in the phase. Thirty per cent of the employees felt execution was successful followed by financing, 30%. As the responses from both property owners and employees show, most respondents (property owners and project employees) were of the view that the project goal of reinstating biological diversity was very important. The property owners were of the view that the re-establishment of the naturalness of the area would contribute favourably towards tourism in the area, which they rated very high. The rating explain why property owners also rated biodiversity conservation and the naturalness of the area equally high. On the other hand, Umgeni Water's top priority is water security and the differing priorities between UWs and eMRRP could be seen as a weakness of the project. However, as a holistic view of biodiversity conservation necessitates protection of water resource in the area, the difference could be synchronised to become a strength ofthe eMRRP (see recommendations). The eMRRP has opportunities on a number of areas such as the opportunity to participate in the national campain on control of invader species by teaming up with WFWP and other stakeholders. Also joinirig this partnership would accord eMRRP stakeholders the pride of contributing to the national campaign on control of invader species. Although there is marked success made by UW in planning, financial support, job creation, gender equity in the eMRRP, there is need to address sustainability of the project. In conclusion, it is clear that the eMRRP started off with most stakeholders having low awareness ofits activities and those ofWFW Programme. However, by clearing invasive alien plants in eMpofana riparian areas, the project has gained support from property owners and its employees. Property owners support the project mainly because of possible re-establishment of naturalness of the area (biological diversity) and the employees give their support mainly because of the employment that they receive. However, the goal of sustainability of the eMRRP is likely to remain elusive as long as priorities are not harmonised: property owners' priority (based on benefits drawn) is biodiversity conservation whereas that of UW is water security. / Thesis (M.Env.Dev.)-University of Natal, Pietermaritzburg, 2000.