Assessing Anthropogenic Impacts on the Persistence of Forest Mammals Within the Indian Ocean Coastal Belt of Southern Kwazulu-Natal Province
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Assessing Anthropogenic Impacts on the Persistence of Forest Mammals within the Indian Ocean Coastal Belt of Southern KwaZulu-Natal Province Yvette C. Ehlers Smith Submitted in fulfilment of the academic requirements for the degree of Doctorate of Philosophy in the Discipline of Ecological Sciences School of Life Sciences College of Agriculture, Engineering and Science University of KwaZulu-Natal Pietermaritzburg Campus 2016 ABSTRACT Over a three-year period, between January 2014 and December 2016, I conducted research within the Indian Ocean Coastal Belt (Coastal Belt) of the Ugu district of south-east KwaZulu-Natal Province, an area that falls within the Pondoland Area of Endemism. The study region consists of a mixed land-use mosaic, where naturally- and anthropogenically-fragmented indigenous forest and coastal thicket/dense bush (hereafter dense bush) patches are nested within an anthropogenic landscape. The major land-use types within the region are agriculture (predominantly sugarcane) and “urban” landscapes (more accurately described as exurban sprawl or rural villages) which are extensively tourism-oriented developments. The mammalian communities of the area have received little research attention in the past, and although ecological parameters have been established for certain species from other regions, the effects of anthropogenic impacts on the persistence of forest mammals within the habitat patches of the Coastal Belt have thus far been unexplored. The persistence of metapopulations within fragmented landscapes depends on matrix composition and permeability; thus, assessing landscape-scale factors within the habitat mosaic and the impact of the anthropogenic disturbance across a sufficiently representative spatial and temporal scale is crucial for conservation planning. I conducted extensive camera-trapping surveys throughout the region within both forest and dense bush habitats that were considered potentially viable for supporting forest-associated mammals. Data collected from camera-trap surveys were analysed in conjunction with geographic land-cover data, fine- scale microhabitat vegetation characteristics and human population densities, to produce models of occupancy probability of targeted forest-associated mammalian species. This facilitated an examination of the various pressures, including habitat quality, habitat availability (patch size), isolation, connectivity, land-use type and human disturbance, on spatial and temporal distribution of behaviours, community functionality, and the concomitant ecosystem services they provide. The models incorporating fine-scale habitat covariates suggested that dense bush habitats may be considered secondary forest regrowth, and were the preferred habitat for the region’s most vulnerable species, the blue duiker (Philantomba monticola). Inter-patch connectivity was found to be an integral factor in maintaining taxonomic and functional diversity. The land-use modelling demonstrated that the current Protected Area Network (PAN), incorporating remnant Coastal Forest patches, did not provide adequate habitat for forest-dependent species, as the majority of the influences therein were negative or neutral. Anthropogenic recreational activities within the PAs may have influenced the spatio-temporal distribution of the species studied. Nocturnal species were negatively influenced by the urban habitat; i however, blue duiker that exhibited more nocturnal activity patterns in urban and agricultural land also exhibited higher occupancy levels within these habitat types. Additionally, results indicated that urban infrastructure, rather than proximity to humans, was more likely the driver of negative relationships with the urban environment. Although it is encouraging to document the tolerance of various species to a certain degree to the disturbance effects within the urban land-use mosaic, this land-use type does not offer official protection and has the highest likelihood of conversion, highlighting the need to protect integral patches within areas where they are vulnerable. The agricultural landscape had no negative effect on the forest-associated mammalian communities. However, when considering the effects of land-use change, the conversion of anthropogenic landscapes to other high impact land-use types, in addition to the original conversion of natural habitats to anthropogenic land uses, may exacerbate detrimental effects on forest-dependent communities. Overall, this research highlights the complexity of the mammalian communities that exist within the Coastal Belt habitats and emphasises the influence of anthropogenic disturbance on their persistence. The anthropogenic landscape matrix is not necessarily impenetrable to the mammal community, but the intensity of development has varied influences on different species. The region comprises a metacommunity of a variety of different species and various ecological functions. These metapopulations do not appear to be static, and assumptions of movement between patches may be made; thus, dispersal, colonisation and recruitment events may also be occurring between habitat patches, for fauna and flora alike. Assessing the threats posed to the ecological viability of a habitat or a metapopulation as the result of various land-use types within a habitat matrix in this way is crucial for developing conservation strategies for species occupying anthropogenic landscapes. The assessment presented here emphasizes the conservation value of natural habitats nested within anthropogenic land-use types, and this body of work contributes toward a synthesis of techniques to best inform conservation management authorities for the protection of not only the forest, but also dense bush habitat, to protect the mammalian communities that inhabit them. ii PREFACE The data described in this thesis were collected within the Ugu district of south-east KwaZulu-Natal, Republic of South Africa from February 2014 to November 2016. Field work was carried out while registered at the School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, under the supervision of Professor Colleen T. Downs and co-supervision of Dr T. Ramesh. This thesis, submitted for the degree of Doctorate of Philosophy in Science in the College of College of Agriculture, Engineering and Science, University of KwaZulu-Natal, School of Life Sciences, Pietermaritzburg campus, represents original work by the author and has not otherwise been submitted in any form for any degree or diploma to any University. Where use has been made of the work of others, it is duly acknowledged in the text. …………………………. Yvette C. Ehlers Smith December 2016 I certify that the above statement is correct and as the candidate’s supervisor I have approved this thesis for submission. ………………………….. Professor Colleen T. Downs Supervisor December 2016 iii COLLEGE OF AGRICULTURE, ENGINEERING AND SCIENCE DECLARATION 1 - PLAGIARISM I, Yvette C. Ehlers Smith, declare that The research reported in this thesis, except where otherwise indicated, is my original research. This thesis has not been submitted for any degree or examination at any other university. This thesis does not contain other persons’ data, pictures, graphs or other information, unless specifically acknowledged as being sourced from other persons. This thesis does not contain other persons' writing, unless specifically acknowledged as being sourced from other researchers. Where other written sources have been quoted, then: Their words have been re-written but the general information attributed to them has been referenced Where their exact words have been used, then their writing has been placed in italics and inside quotation marks, and referenced. This thesis does not contain text, graphics or tables copied and pasted from the Internet, unless specifically acknowledged, and the source being detailed in the thesis and in the References sections. Signed: ……………………………………… Yvette C. Ehlers Smith November 2016 iv COLLEGE OF AGRICULTURE, ENGINEERING AND SCIENCE DECLARATION 2 - PUBLICATIONS DETAILS OF CONTRIBUTION TO PUBLICATIONS that form part and/or include research presented in this thesis. Publication 1: Yvette C. Ehlers Smith, David A. Ehlers Smith, T. Ramesh and Colleen T. Downs. The importance of microhabitat structure in maintaining forest mammal diversity and abundance in a mixed land-use mosaic. Biodiversity and Conservation- provisionally accepted Author contributions: YCES conceived paper with DAES, TR and CTD. YCES and DAES collected the data. YCES analysed the data and wrote the paper. DAES, T.R and CTD contributed valuable comments to the manuscript. Publication 2 Yvette C. Ehlers Smith, David A. Ehlers Smith, T. Ramesh and Colleen T. Downs. Forest habitats in a mixed urban-agriculture mosaic landscape: patterns of mammal occupancy. Submitted. Author contributions: YCES conceived paper with TR and CTD. YCES and DAES collected the data. YCES analysed the data and wrote the paper. DAES, TR and CTD contributed valuable comments to the manuscript. v Publication 3 Yvette C. Ehlers Smith, David A. Ehlers Smith, T. Ramesh and Colleen T. Downs. Predators and anthropogenic disturbance influence spatio-temporal distribution of forest antelope species. Submitted. YCES conceived paper with TR and CTD. YCES and DAES collected the data. YCES analysed the data and wrote the paper. DAES, T.R and CTD contributed valuable comments to the manuscript. Publication 4 Yvette C. Ehlers Smith, David A. Ehlers Smith, T. Ramesh and Colleen T. Downs. The influence