Giraffe, www.judyrose.wordpress.com Duiker, www.kareesafris.co.za Black Rhino, www.news.bbc.co.uk Elephant, www.freewebs.com Impala, www.rennersafaris.com. In order to optimize the spatial distribution of conservation efforts and how best to protect native species, an understanding of the major determinants that structure ecological communities and ecosystems is required. Using GIS and statistical analyses, we specifically investigated the effect of the temporal expansion of an exotic invasive plant (Chromolaena odorata) on the critically endangered black rhinoceros.
Black rhinoceros used different strategic and metabolic mechanisms to successfully compete within the same foraging height range as other, smaller browsers. Where use has been made of the work of others, it has been duly acknowledged in the text.
PLAGIARISM
FOREWORD The experimental work described in this thesis was carried out in the School of Biological and Conservation Sciences, University of KwaZulu-Natal, Westville, under the direction of Professor Robert Slotow and co-supervision of Professor Han Olff of the Community and Conservation Ecology Group , Center for Ecological and Evolutionary Studies, Rijksuniversiteit Groningen, Haren, The Netherlands, and these supervisors are acknowledged for their guidance as co-authors of Chapters 2 and 3.
PUBLICATIONS
GENERAL INTRODUCTION
- STUDY SITE
- OVERALL AIMS AND OBJECTIVES
- REFERENCES
Humans have caused the extinction of 5–20% of species in many organismal groups, and human mobility has transported organisms across geographic barriers, leading to the risk of biotic homogenization through species invasions (McKinney and Lockwood 1999; Chapin et al. Across throughout the African continent, the distribution of ungulate species richness is closely related to the distribution of the savanna biome (Turpie and Crowe 1994), with hotspots of diversity under intermediate rainfall and high soil fertility (Olff et al. 2002) Dispersal is an important process in population regulation, but in small isolated protected areas, dispersal is limited, often by fenced boundaries, leading to accelerated overexploitation of the natural vegetation and rapid loss of biodiversity (Western and Ssemakula 1981; Owen-Smith 1983b; Chapin et al. 2000).
Reconstruction and mechanisms of invasion of a diverse African savanna reserve by the alien plant Chromolaena odorata. A study of the extent and nature of alien plant infestations in the central compound with recommendations for their future control.
FOOD PREFERENCES AND FEEDING INTERACTIONS AMONG BROWSERS, IN
- ABSTRACT
- INTRODUCTION
- METHODS
- Study site
- Utilization by browsers of the main habitat types
- Morphological and biochemical plant characteristics
- RESULTS
- Utilization by browsers of the main habitat types
- Morphological and biochemical plant characteristics
- DISCUSSION
- REFERENCES
17 Table 2.1: Categorization of 20 vegetation communities (Whateley & Porter 1983) into seven main habitat types: six habitats. We calculated the percentage of trees browsed by black rhino, elephant and other browsers per plot. For each of the six wood habitat types, we plotted the relative abundance of each tree species within height m as a proportion of the total number of individual trees sampled in this height class (no individuals = 9,894) and sorted the species according to decreasing abundance (Fig. 2.2a-f).
Niche overlap (Pianka 1973) (or in this case feeding species overlap) was calculated per habitat type and per plot, to represent the proportion of foraging species overlap between species pairs of the three different browser groups, within the m elevation class. We collected leaf and twig samples from 52 of the most common species within HiP in July 2007. These three habitat types provided the main food source, evidenced by the fact that a large proportion of woody species are used by all browsers within a narrow habitat range. SAD (Fig. 2.2a - c).
Dietary overlap of black rhinoceros and elephant was the lowest of the three combinations of species pairs (average overlap 0.12) indicating that the diet of black rhinoceros and elephant consisted of different species. Therefore, direct management of natural systems is essential to sustain sustainable populations within these diverse communities (Owen-Smith 1988; Chapin et al. 2000). The third ranking axis (MaxHgt) was found to be independent of the SLA axis (Westoby et al. 2002) and browser preference was intermediate tending towards shorter species (i.e. lower MaxHgt, lower LFD and low TWD), especially from the elephant.
Differences in body size create variation in the availability of the food resource (Ritchie and Olff 1999; du Toit 2003). Diet species overlap between browsers of different sizes may be higher due to the vertical division in the use of the food resource (du Toit 2003;. Black rhinoceros also has a wide diet breadth that exploits many of the rarer tree species (Oloo et al. 1994 ; Emslie) 1999), thereby counteracting the effects of the toxin by mixing abundant (but toxic) forage with many species of high nutritional quality that are biochemically complementary and which mitigate the effects of the toxin (Freeland and Janzen 1974; Provenza 1995; Iason and van Wieren 1999; Provenza 2003).
Threats to key tribal populations must be carefully managed and monitored, and uncontrolled elephant population expansion has been identified as a potential threat to the survival of the black rhino (Oloo et al. 1994; Emslie and Brooks 1999). THE EFFECT OF THE INVASIVE WEED CHROMOLAENA ODORATA ON THE CRITICAL ENDANGERED BLACK RHINO IN HLUHLUWE-IMFOLOZI PARK.
THE EFFECT OF THE INVASIVE WEED CHROMOLAENA ODORATA ON THE
- ABSTRACT
- INTRODUCTION
- METHODS
- Study site
- Spatial redistribution of black rhino
- Changes in home range
- Changes in diet choice
- RESULTS
- Spatial redistribution of black rhino
- Changes in home range
- Changes in diet choice
- DISCUSSION
- REFERENCES
The black rhinoceros (Diceros bicornis minor) is one of these critically endangered species, whose global population has declined from several hundred thousand individuals to 3700 individuals (Sherriffs 2007; IUCN 2008). In the longer term, species in a community can shift towards communities that are resistant to the effects of the invader (Levine et al. Raimundo et al. 2007), Chromolaena odorata is a species that has now invaded the tropical regions of Asia, Africa and the islands of the Pacific Ocean, and worldwide is among the worst 100 invasive species (ISSG 2008).
The main distribution of the plant was concentrated towards the northern part of the park (Howison, O. et al. unpublished data) while the southern areas remained relatively free of C. In this article, we assess the possible negative effect of the expansion of the exotic invader C. Second, we investigate the spatial reorganization of the black rhino by calculating home ranges from individual observations, which differ in location and size between two periods (before and during the large expansion of C. odorata is compared) by HiP) for male and female rhinos.
To map the spatial redistribution of black rhinos within HiP, we used spatially explicit black rhino sighting data collected by rangers in HiP while conducting their daily security patrols in the Park. We then plotted the observed visual density against distance from ranger outpost, for each of the two time periods. The map indicates that spatially some areas of the park were heavily invaded in the north while the southern areas remained relatively free of invasion.
For each individual tree, we noted the species and measured the height of the tree (from ground to top of living material). During period two, a significant shift in the spatial distribution of rhinos had occurred (with 30 or more sightings). The black rhinos concentrated in the southern part of the park and the total number of black rhinos found dropped to 30. Average rainfall domestically The ranges in the north were significantly higher than in the south (2-way ANOVA: F R2 = 0 .36, p < 0.001), and both male and female black rhinos generally moved from the high rainfall areas (high prevalence of C. odorata) and were now concentrated more southwards (Table 3.1).
Expansion occurred in all vegetation types in the northern part of the park (Howison, O. et al. unpublished data), with a particular preference for vegetation at high altitudes and with higher annual rainfall (Kriticos et al. 2004; this study). This reduced the areas of rhinoceros settlement in the northern HiP region and caused shifts in the spatial organization of the population towards the southern region where C.
GENERAL DISCUSSION
- REFERENCES
However, diet diversity was different between browsers, where the diversity of the diet composition of the other browser group was significantly greater than that of the black rhinoceros or elephant. My study highlighted novel strategic and metabolic mechanisms by which the black rhinoceros claims an exclusive niche in order to successfully compete with other browsers using available browsing in the same height range (Chapter 2). The black rhino showed a wide range of diets, preferring abundant but toxic forage species and adding many rare higher quality forage species that are biochemically complementary to their diet.
I propose that the black rhino uses this strategy in combination with unique detoxification pathways to mitigate the effects of toxins (Jenkins and Wright 1988; Dearing and Cork 1999; Provenza 2003). Overlap calculations for feeding species (Pianka 1973) indicated that the overlap between elephants and other browsers and between black rhinos and other browser interactions was greater than between black rhinos and elephants. This is a major concern as this park hosts one of the largest populations of the critically endangered black rhino (Diceros bicornis) (Slotow et al. 2001).
Further research is required to assess the positive or negative effects this has had on the spatial organization of the black rhinoceros population, given the vulnerability of the vegetation to reinvasion if a wetter cycle returns (Leslie and Spotila 2001; Black rhinoceros are critically endangered and current management is focused on maximizing production within larger populations (Hearne and Swart 1991; Emslie and Brooks 1999) First, a high heterogeneity of forage species is required (Oloo et al. 1994) that rhinos blacks to successfully use their preferred diet consisting of members of the Euphorbiaceae (Emslie 1999).
Other black rhinos are vulnerable to habitat degradation resulting from the encroachment of exotic invasive species into primary habitat (McKinney and Lockwood 1999). Local management of the black rhino population within HiP, one of the largest black rhino populations (Linklater and Swaisgood 2008), has involved high removal rates in recent years (EKZNW unpublished data), and the effects this will have need to be investigated. on the spatial organization of the population and the recent decline in the number of black rhinos. Impact of giraffe, rhinoceros and elephant on the habitat of the black rhinoceros sanctuary in Kenya.
