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Rozen-Rechels, David, 2015. The repulsive shrub : impact of an invasive shrub on habitat selection by African large herbivores. Second cycle, A2E. Umeå: SLU, Dept. of Wildlife, Fish and Environmental Studies

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Abstract

Invasive plants, growing and spreading outside of their native range, can severely modify ecosystems. Herbivory has often been seen as a potential control of invasions, but has rarely been considered as a potential impacted trophic level. Considering the habitat selection by large herbivore being a reflection of their feeding habits and predator avoidance, I studied the impact of the invasive Chromolaena odorata on African large herbivores in Hluhluwe-iMfolozi Park, KwaZulu-Natal, South Africa. This plant is not eaten by the animals but affects the diversity of the grass species, the height and cover of woody species and can create high and thick walls as a barrier for most animals. Abundance of 14 species of herbivores was estimated by dung counting, and the presence and density of the invasive shrub was estimated every 5 meters on 24 transects in the park in 2004 (high density of invasive) and 2014 (low density of invasive). This data was used to understand a predictive habitat selection analysis (Resource Selection Functions) and to analyse the recolonization of previously invaded patches based on the change of dung abundance. A Principal Component Analysis showed that closed woody habitats are the most invaded. The results are a mirror of the high heterogeneity of habitats and herbivores in African savannas. Grazers (buffalo, zebra, warthog, and wildebeest) as well as browsers (nyala) avoided high density patches that are a physical barrier to selection. Grazers seem also to avoid less dense patches where food availability might be diminished and where ambush predators could hide. However, bushpigs select invaded patches, which may be used as a shelter against predators for example. Other species appear to ignore the invasion; because their home area does not overlap the invaded area (impala) or because the invasion does not affect them (elephant).

Main title:The repulsive shrub
Subtitle:impact of an invasive shrub on habitat selection by African large herbivores
Authors:Rozen-Rechels, David
Supervisor:Cromsigt, Joris and te Beest, Mariska
Examiner:Singh, Navinder
Series:Examensarbete i ämnet biologi / Sveriges lantbruksuniversitet, Institutionen för vilt, fisk och miljö
Volume/Sequential designation:2015:2
Year of Publication:2015
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:None
Department:(S) > Dept. of Wildlife, Fish and Environmental Studies
Keywords:invasive plants, large herbivores, savanna, habitat selection, clearing
URN:NBN:urn:nbn:se:slu:epsilon-s-4132
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-4132
Subjects:Plant ecology
Animal ecology
Language:English
Deposited On:20 Feb 2015 15:25
Metadata Last Modified:20 Feb 2015 15:25

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