Woody vegetation change and elephant water point use in Majete Wildlife Reserve : implications for water management strategies

Wienand, Jessica Joy (2013-12)

Thesis (MScConEcol)--Stellenbosch University, 2013.

ENGLISH ABSTRACT: The confinement of many elephant (Loxodonta africana) populations in southern Africa to fenced reserves has made the management of such reserves difficult as elephants are a keystone species. Elephants are also water-dependent; therefore the availability of water affects the location, extent and intensity of elephant impacts on vegetation. Majete Wildlife Reserve (Malawi) has undergone reform, during which it was fenced, artificial waterholes (AWPs) were created and wildlife reintroduced, including 220 elephants. Concerns have arisen as to the impact elephants may be having on the vegetation. In this thesis, two studies were conducted, along with a review of literature on elephant interactions with surface water. Woody vegetation changes in Majete were assessed by comparing woody vegetation cover datasets (based on remote-sensed vegetation classifications) of the reserve for 1985, 1990, 2000 and 2010. Woody cover loss was high between 2000 and 2010, therefore points of woody cover loss were further analysed in a spatial analysis. Using spatial and non-spatial environmental data, the effects of rainfall, fires, terrain (altitude, aspect, slope, hill and valley characteristics) and proximity to perennial water on woody vegetation cover were tested. Data analyses indicated that woody cover loss may have been caused by differing combinations of drought and herbivory or fire in different areas of the reserve. Where woody cover loss was attributed to herbivory, points of loss were not associated with proximity to perennial water. It was suggested that this is due to high perennial water availability in Majete, which would not limit herbivore foraging ranges in the dry season. Woody cover loss could not, however, be attributed to elephants in this study and further information on their use of and impacts around perennial water points was required. In a further study, the hypothesis tested was that different water point types (rivers, AWPs and springs) would be used at different intensities by elephants, and that perennial rivers would experience the most use. Elephant usage (including visits to water points, browsing levels and path use around water points) of selected perennial water points in Majete was monitored in the wet and dry season. The effects of season, water point characteristics (type, size and water quality) and habitat context (surrounding vegetation type, elevation and proximity to other water points) on elephant water point use were then tested. Elephant water point use was affected by season, as well as water point altitude and surrounding vegetation type. In areas of high perennial water availability, elephant browsing around water points did not decrease with increasing distance. It was suggested that this too could be because elephant browsing activity is not limited by water availability in Majete. Based on the findings of both studies, recommendations for water, elephant and fire management in Majete were proposed and discussed.

AFRIKAANSE OPSOMMING: Die beperking van baie olifantpopulasies tot omheinde reservate in Suider-Afrika bemoeilik die bestuur van hierdie parke omdat olifante (Loxodonta africana) as 'n hoeksteenspesie beskou word. Olifante is ook water-afhanklik en daarom word die plek, omvang en intensiteit van olifante se impak op plantegroei deur die beskikbaarheid van water beïnvloed. Die Majete Wildlife Reserve (Malawi) het hervorming ondergaan waartydens dit omhein is, kunsmatige waterpunte (AWP‟s) geskep is en wilde diere, insluitend 220 olifante, hervestig is. Kommer het ontstaan rondom die moontlike impak wat olifante op die plantegroei mag hê. In hierdie tesis word twee studies sowel as ʼn literatuurstudie aangaande olifantinteraksies met oppervlakwater uitgevoer. Houtagtige plantegroei veranderinge in Majete is geassesseer deur data van plantegroei-bedekking (op afstandswaarnemings van plantegroeiklassifikasies gebaseer) vanuit 1985, 1990, 2000 en 2010 met mekaar te vergelyk. Die verlies van houtagtige-bedekking tussen 2000 en 2010 was hoog en gevolglik is hierdie areas verder deur ʼn ruimtelike analise ontleed. Deur die gebruik van ruimtelike en nie-ruimtelike omgewingsdata, kon die effek van reënval, brande, terrein (hoogte, aspek, helling, heuwel- en vallei-eienskappe) en nabyheid aan standhoudende water op houtagtige plantegroei getoets word. Data-analise het aangedui dat verlies van houtagtige-bedekking deur verskillende kombinasies van droogte, herbivooraktiwiteit of brande in die verskillende dele van die reservaat veroorsaak word. Waar verlies van houtagtige-bedekking toegeskryf kon word aan herbivore, was die punte van verlies nie geassosieer met nabyheid aan standhoudende water nie. Daar is voorgestel dat hierdie waarneming verband hou met die hoë beskikbaarheid van water in Majete, wat gevolglik nie herbivoorbeweiding in die droë seisoen beperk nie. Hierdie studie kon dus nie die verlies van houtagtige-bedekking aan olifantteenwoordigheid toeskryf nie en verdere inligting rondom die verbruik en impak van olifante op standhoudende waterpunte word benodig. In 'n verdere studie is die hipotese dat verskillende tipes waterpunte (riviere, AWP‟s en fonteine) teen verskillende intensiteitsvlakke deur olifante benut word, en dat standhoudende riviere die meeste verbruik sou ervaar, getoets. Verbruik van geselekteerde standhoudende waterpunte deur olifante (insluitend besoeke aan waterpunte, beweiding en paadjiegebruik rondom waterpunte) in Majete is gedurende die nat- sowel as droë seisoene gemonitor. Die effek van seisoen, waterpunt-eienskappe (tipe, grootte en watergehalte) en habitatkonteks (omliggende plantegroei, hoogte bo seespieël en nabyheid aan ander waterpunte) is op die waterpuntverbruik van olifante getoets. Die waterpuntverbruik van olifante word deur seisoen, hoogte bo seespieël en omliggende plantegroei beïnvloed. In gebiede met hoë beskikbaarheid van standhoudende waterpunte, het olifantbeweiding rondom waterpunte nie met toenemende afstande afgeneem nie. Daar is voorgestel dat hierdie waarneming ook toegeskryf kan word aan die feit dat olifantbeweiding nie deur die beskikbaarheid van water in Majete beperk word nie. Gebaseer op die bevindinge van beide studies, word daar aanbevelings vir water-, olifant- en brandbestuur in Majete voorgestel en bespreek.

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