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International Institute for Geo-Information Science and Earth Observation (ITC) 2003

Control of invasive Chromolaena odorata : an evaluation in some land use types in KwaZulu Natal, South Africa

Phoebe Luwum

Titre : Control of invasive Chromolaena odorata : an evaluation in some land use types in KwaZulu Natal, South Africa.

Auteur : Phoebe Luwum

Etablissement de soutenance : University of Twente International Institute for Geo-Information Science and Earth Observation (ITC)

Grade : Master of Science in Geo-Information Science and Earth Observation 2003

Résumé _ Chromolaena odorata (L.) R. M. King and H. Robinson, is a neotropical Asteraceae considered to be one of the most aggressive invasive plants in tropical and sub-tropical areas. Chromolaena odorata is said to be a particular threat in KwaZulu Natal - South Africa, hindering biodiversity conservation by changing vegetation composition, reducing grazing for large herbivores and reducing tourism potential by obstructing game and bird viewing in recreation areas. In silviculture C. odorata is a problem during the establishment and harvesting phase, increasing costs of production, and adversely affecting crops. The plant reduces the acreages that can be effectively managed by farmers, particularly in small-scale agricultural land. The fire hazard potential of C. odorata due to its flammable foliage is frequently emphasized. Different management programmes aimed at elimination of plant invasions have been in operation for more than a decade, managed by government agencies within the conservation areas and urban areas, two major forestry companies within the production forestry areas and private and communal land owners within the subsistence agriculture areas. Varying degrees of success have been achieved, with some rapid (re-)infestation taking place in some areas. It has been suggested that this lack of success stems from the differences in management and strategies within different land use types. The study assesses the link between land use/management and the control of C. odorata within conservation, production forestry, subsistence agriculture, commercial/residential and commercial agriculture land use types. Using a combination of remote sensing, GIS and statistical techniques, a comparison is made of the status of C. odorata across and within land use types. Chromolaena odorata abundance is taken as the main response variable and indicator of success in management of the alien plant. Differences in control strategies are investigated as a possible explanatory variable. The current state of C. odorata on different land use types investigated differs considerably, especially between the highly infested conservation and production forestry and other land use types. Strategies used in the control of C. odorata range from relatively intensive and institutionalised strategies within the conservation and production forestry areas, to more ad hoc arrangements within the commercial agriculture, subsistence agriculture and urban centres. The conclusion is that differences in control strategies used within the conservation areas or the production forest seem to have only a marginal effect on the state of C. odorata . Significant differences are seen between land use types and attendant differences in land management practices.

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Page publiée le 31 janvier 2018