Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: As the world’s human population increases, more pressure is placed on the management of natural
resources. In response, we need an efficient means of monitoring, not only the quantity of these
resources but also their quality. No comprehensive standard metric has been developed to assess
environmental quality of a biotope, or to define the nature and extent of environmental degradation at
this spatial scale. Currently in conservation management, various landscapes are being evaluated for
spatial heterogeneity, by making use of species surrogates such as species richness, relative abundance,
diversity indices and phylogenetic indices, as well as environmental surrogates. These values are then
used towards conservation, where those systems with high intrinsic heterogeneity are usually considered
more important than those with low heterogeneity at least when given the choice between the two. Yet,
the actual quality of the biotopes within the landscapes is rarely taken into consideration. This study
therefore develops and tests a Biotope Quality Index (BQI) to study this point in depth. The BQI makes
use of arthropod assemblages as bioindicators of the level of disturbance within a biotope.
Firstly, I summarize the literature on the concept of environmental health, and define it as “An ecosystem
is healthy, if it can sustain an optimal number of species with optimal population sizes and their
ecological processes, thus providing and optimal heterogeneous sustainable system with sufficient
resources, and indicated adequate resistance when under perturbational stress, but still allowing natural
succession to take place” Against this background, I then review the use of certain Arthropoda as
bioindicators, as arthropods are small, mobile, environmentally sensitive, easily sampled, and readily
available. These features together make arthropods good subjects for testing the BQI. I then compare the BQI with diversity indices currently used as surrogates of biotope quality. The
outcome was that the BQI stood out as a significantly better indicator than the currently available indices
for assessing environmental quality of a biotope. Furthermore, during the selection process, I also tested
the use of guilds for BQI evaluation, and found that the scavenger (represented by Formicidae) and
decomposer (represented by Collembola) guilds were the most significant. The effect of seasonality was
also tested. I found the best results with the BQI were when data are pooled from all seasons of the year.
A case study, making use of the BQI evaluation, was conducted at a site in the Cape Floristic Region,
South Africa (Jonkershoek Valley). BQI results suggested that the agricultural management and tourism
within the locality might have an effect on biotope quality. This study has shown that use of the BQI is a
useful and practical management tool for evaluating environmental quality of a biotope towards
conservation management. / AFRIKAANSE OPSOMMING: Met die vermeerdering van mense op die Aarde, wat meer druk plaas op ons natuurlike hulpbronne en
omgewing is daar ‘n aanvraag na doeltrefende maniere wat nie net die kwantiteit maar ook die kwaliteit
van die hulbron evalueer. Geen betroubare standard bestaan om biologiese kondisies of die
kwaliteit van n omgewing te meet nie. Heidiglik maak wetenskaplikes staat op die bepaling van
diversiteit en ander voogde soos spesies rykheid en diversiteit indeksies as voog vir kwaliteit.
Die waardes word dan gebruik binne die omgewings bestuur praktyke en bevooroordeel
omgewings met ‘n hoë diversiteit, terwyl die kwaliteit van omgewing skaarslik na gekyk word.
Hiervolgens, onwikkel ons n Omgewings Kwaliteit Indeks (OKI), wat gebruik maak van
Arthropoda saamestellings as bioindikator van die vlak van verval binne ‘n omgewing. Verder
sluit die tesis n literatuur studie van die omgesings gesondheid teorie, en die gebruik van
arthropoda as bioindikators. As basis van die studie, definieër ons ‘n gesonde omgewings as ‘n
omgewing wat’ n optimal hoeveelheid spesies en hulle ekologiese prosesse kan handhaf, en
daarom verwys na ‘n diverse onderhoubare sisteem met genoegsame hulpbronne en kan
genoegsame weerstand bied onder omgesings stres, maar gee geleentheid vir naturlike suksesie
om plaas te vind
Ons het verder die OKI getoets teen ander diversiteit’s indeksies, waar ons gevind het dat die
OKI evaluering ‘n statistiese beklemtonde verskil toon as bioindikator van omgewings kwaliteit.
Verder het ons voorkeer getoets, in gedrags groupe en gevind dat die versamellaars groep
(verteeenwoordig deur Formicidae) en die afbrekers groep (verteenwoordig deur Collembola) die
beste resultate toon. Seisoene het ook ‘n uitwerking en ons het gevind die groupeering van data
ingesamel oor alle seisoene die beste resultate getoon. ‘n Ondersoek studie wat gebruik maak van die OKI evalueering, was gekondakteer in die
Jonkershoek valei en het getoon dat die landbou plaagbestuur en toerusme ‘n negatiewe effek het
op die omgewing. Verder het die OKI evalueering getoon dat aanplanting van Denne plantasies
die kwaliteit van ‘n omgewing verlaag. Die studie het verder getoon dat die OKI evalueering ‘n
betroubare evalueerings metode is vir die bestuur van ‘n omgewings, terwyl die diversiteits
indeksies nie geskik is as bioindikator van omgewings kwaliteit nie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/86403 |
| Date | 04 1900 |
| Creators | Bredenhand, Emile |
| Contributors | Samways, M. J., 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 | xviii, 234 p. : ill. |
| Rights | Stellenbosch University |
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