Thesis (MSc)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: Alien trees, Pinus spp. and Eucalyptus spp., affect ants negatively in the Cape Floristic
Region (CFR), a global biodiversity hotspot in South Africa. They reduce ant abundance
and species richness, thus also changing ant assemblage structure. This is alarming,
because almost 1300 species of plant species in the CFR are dispersed by certain
indigenous ants, and thus there is concern for an indirect effect on indigenous plant
assemblages. One of the most impacting ant species on seed dispersal is the invasive
Argentine ant (Linepithema humile (Mayr)), which discards seeds outside its nest, where
they do not germinate. Ten sites, on Vergelegen Wine Estate, were selected to explore
these effects of alien plants. These varied from invaded to non-invaded sites. Each site
consisted of six sampling points, which in turn consisted of four pitfall traps left out for
seven days, during December 2005, February 2006, May 2006 and September 2006.
Forty species of ant were sampled, and various analyses used to illustrate the comparative
effects of plant invasion. All analytical methods showed that invasive alien plants had a
significant impact on the abundance and richness of the ant species assemblage, by
creating a dense canopy cover that changed the abiotic environment of the epigaeic ants’
habitat. Furthermore, increased alien tree invasion correlated significantly with Argentine
ant abundances. The Argentine ant displaced Pheidole capensis and Camponotus spp.,
while it decreased the abundances of commonly-occurring indigenous ants, such as
Lepisiota capensis and Plagiolepis spp. Displacement by the Argentine ant may be a
result of indirect competition for food resources. The effects of invasive aliens are
synergistic in that there is a cascade effects from initial plant invasions to subsequent
animal invasion. / AFRIKAANSE OPSOMMING: Indringer bome, Pinus en Eucalyptus, affekteer miere op negatiewe wyse in die Kaap
Florsitiese Streek (KFR), ‘n area in Suid Afrika van belang t.o.v. globale biodiversiteit.
Hierdie uitheemse indringer bome verminder hulle hoeveelheid en spesies rykheid. Die
bogenoemde is kommerwekkend omdat meer as 1300 plant spesies in the KFR versprei
word deur miere. Die verandering in hoeveelheid en versameling van inheemse miere kan
dus ernstige implikasies hê op die saad verspreiding van inheemse plant spesies. Een van
die mees verwoestende effekte op saad verspreiding is veroorsaak deur die indringer
Argentynse mier (Linepithema humile (Mayr)), wat sade neer werp buite hulle neste,
waar hulle nie suksesvol kan ontkiem nie. Tien monsterings-tereine was geselekteer om
die bogenoemde effekte te ondersoek op Vergelegen Landgoed. Hierdie het afgewissel
van indringer tot skoon tereine. Elke terrein is op ses versamelings-plekke gemonster,
met vier pitvalle, wat oopgelê het vir sewe dae gedurende Desember 2005, Februarie
2006, Mei 2006 en September 2006. 40 spesies van miere was gemonster. Indringer
plante het ‚n betekenisvolle impak gehad het op die hoeveelheid en rykheid van die mier
gemeenskappe, deur die skepping van ‚n dig baldakyn wat die abiotiese omgewing van
die miere se habitat verander het. Die vermeerdering van indringer plante veroorsaak die
vermeerdering van Argentyne miere. Kanonieke Mede-Respons Analise illustreer dat die
Argentynse mier Pheidole capensis en Camponotus spp. verplaas het, terwyl dit ander
inheemse mier getalle verminder het, soos Lepisiota capensis en Plagiolepis spp. Die
verplasing deur die Argentynse mier mag die resultaat wees van indirekte wedywering vir
hulpbronne. Die effekte van indringer species is dus sinergisties deur dat ‚n kaskade effek
ontstaan vanaf plant tot dier indringer spesies.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21759 |
| Date | 03 1900 |
| Creators | Schoeman, Colin Stefan |
| Contributors | Samways, Michael, Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | iv, 81 leaves : ill., map |
| Rights | Stellenbosch University |
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