Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: The conservation of biodiversity is becoming increasingly challenging as habitats are
disturbed, fragmented or destroyed. Although nature reserves now cover more than 10 %
of the earths’ surface it has become clear that more will have to be done to ensure the
long-term survival of species. Therefore, focus is increasingly shifting towards
conserving biodiversity in natural and semi-natural remnants in human-influenced areas.
This study aimed to determine the contribution of remnants in human-influenced areas to
the conservation of biodiversity in the Cape Floristic Region (CFR) lowlands, using
ground-dwelling arthropods, specifically ants, as the focal taxon. Initially, base-line
information of arthropods and in particular ants was obtained. Sampling arthropods
generally involves a large sample effort. Therefore maximizing sampling effort for ants
in the CFR was investigated by trapping ground-dwelling ants at a single locality.
Doubling the number of grids of pitfall traps was found to be more effective in trapping a
greater number of species than doubling the duration of sampling. Therefore increasing
spatial sampling intensity rather than sampling duration maximizes sample effort for CFR
ants. Also, the seasonal changes of ground-dwelling arthropods, including ants, were
determined by sampling four times during the year at a single locality. Overall arthropod
abundance was found to peak in summer while dropping to a minimum in winter. This
pattern was mirrored by that of the ants, indicating that ant results have a broader
relevance than to ants only. The ground-dwelling fauna was dominated by ants
emphasizing their importance in the CFR lowlands, and demonstrating that ants are an
appropriate flagship taxon for epigaeic arthropod diversity in the CFR. Finally the
contribution of remnants in human-influenced areas to the conservation of the CFR was
investigated. A nested hierarchical approach was used, where five localities were selected
across the CFR, each containing one reserve site and one site with natural remnants. Ants
were sampled, along with environmental variables, namely weather, vegetation and soil.
Overall, remnants were found to support similar ant assemblages to those of reserves.
However for individual localities some remnants were significantly different to their
reserve counterparts. Differences in ant assemblages were found to be greater between
localities than between reserves and remnants. The relatively high heterogeneity of ants found in this study emphasizes the conservation significance of invertebrates along with
that of plants in the CFR. Remnants clearly show the potential to conserve ant
assemblages, however correct management is needed for these areas to maximize their
potential. Disturbances such as the presence of the invasive Argentine ant and increasing
soil nutrients by fertilization, pose a distinct threat to the ability of remnants to conserve
ant assemblages. This study has shown that remnants currently support ant assemblages
representative of those present in the CFR today. Therefore, some remnant patches of
habitat in agricultural areas currently do contribute highly to the conservation of a
functional important taxon in this global biodiversity hotspot, and if managed correctly,
may continue to do so in the future. / AFRIKAANSE OPSOMMING: Die vernietiging en fragmentering van habitatte maak die bewaring van biodiversiteit al
hoe meer van ‘n uitdaging. Alhoewel natuur reservate reeds meer as 10 % van die aarde
se oppervlak beslaan is dit duidelik dat meer gedoen sal moet word vir die lang-termyn
voortbestaan van spesies. Dus word die fokus van biodiversiteit-bewaring toenemend
gerig op bewaring van natuurlike en semi-natuurlike fragmente in menslik-beinvloede
gebiede. Die doel van hierdie studie was om te bepaal wat die bydrae van fragmente van
natuurlike veld in menslik-beinvloede gebiede is tot die bewaring van die streek. Dit is
gedoen deur van grond-lewende geleedpotiges en spesifiek, miere in die Kaapse floraryk
(CFR) gebruik te maak. Aanvanklik is kennis ingewin oor die geleedpotiges en spesifiek
miere in die omgewing. Omdat die versameling van geleedpotige diere gewoonlik baie
moeite vereis is ‘n maksimum steekproef gedoen by ‘n enkele lokaliteit. Daar is gevind
dat ‘n verdubbling van die aantal ruitsteekproefnemings met vanggate meer effektief is
om miere te vang as ‘n verdubbling in die tydperiode wat vanggate oop is. Dus, is ‘n hoër
ruimtelike steekproef intensiteit meer effektief in vergelyking met ‘n langer tydsduur vir
miere in die CFR. Die seisoenale veranderinge van grond-lewende geleedpotiges, sowel
as miere, was ook bepaal. Dit was gedoen deur vier seisoenale steekproewe te doen by ‘n
enkele lokaliteit. Die totale geleedpotige-talrykheid was die meeste gedurende die somer
en die minste in die winter. Die miertalrykheid het ook hierdie patroon weerspieël. Dit
dui daarop dat veranderinge in mier versamelings van breër belang is vir alle grondlewende
geleedpotiges. Miere was die dominante grond-lewende geleedpotiges en
beklemtoon die belangrikheid van miere in die CFR, sowel as hulle toepaslikheid as
vlagskip taksa vir grond-lewende geleedpotige diversiteit in die CFR. Laastens was die
bydrae van gefragmenteerde natuurlike veld in menslik–beinvloede gebiede tot die
bewaring van die CFR ondersoek. ’n Krimpende/ genestelde hiërargies benadering is
gebruik in vyf geselekteerde lokaliteite, elk het bestaan uit ‘n area in ‘n natuur reservaat
en ‘n area in ‘n naasliggende fragment. Miere was versamel saam met ‘n verskeidenheid
omgewings veranderlike, naamlik weer, plantegroei en grond. In die algemeen is gevind
dat fragmente en reservate gelyksoortige mier versamelings het. Daar was wel gevind dat
party fragmente aansienlik verskillend was van die reservaat teenstuk. Verskille in mier versamelings tussen lokaliteite was groter as verskille tussen reservate en fragmente. Die
relatief hoë heterogeniteit van miere beklemtoon die bewaringsbelang van invertebrate
saam met dié van plante in die CFR. Dit is duidelik dat fragmente wel ‘n potensiale
bydrae kan maak om die mier versamelinge te bewaar, maar gepaste bestuur is nodig om
hierdie potentiaal te maksimaliseer. Versteurings soos die teenwoordigheid van die
indringer Argentynse mier en toenemende grondvoedingstofkonsentrasie as gevolg van
bemesting is ‘n groot bedreiging tot die vermoë van fragmente om mier versamelings te
bewaar. Hierdie studie wys dat mier versamelings in gefragmenterde areas
verteenwordigend is van die algemene mier versamlings wat op die oomblik in die CFR
is. Dus lewer party fragmente in landbou gebiede op die oomblik ‘n wesenlike bydrae tot
die bewaring van ‘n funksioneel belangrike takson in hierdie globale
biodiversiteitsbrandpunt en die bydra sal volhoubaar wees met korekte bestuur.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/21551 |
| Date | 12 1900 |
| Creators | Boonzaaier, Carmen |
| Contributors | McGeoch, M.A., Parr, C.L., 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 | Unknown |
| Type | Thesis |
| Format | viii, 184 leaves : ill., maps |
| Rights | Stellenbosch University |
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