Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Conservation planners use many traditional biodiversity conservation tools to help alleviate
the global biodiversity crisis. However, ongoing biodiversity loss has stimulated the
development of new and improved methods for conserving biodiversity. One such new
conservation tool is the mesofilter approach. Mesofilters are biotic or abiotic ecosystem
elements which are critical to the well-being of many species, and therefore could help to
explain spatial heterogeneity in species across a landscape. It is also complementary to more
traditionally used concepts such as coarse- and fine-filter conservation concepts. Applying the
mesofilter approach in protected area, conservancy, or land-sparing design and management,
could optimise biodiversity conservation in a rapidly developing world. For example, the
timber industry has been pro-active in its approach to lessen biodiversity loss, by optimising
design and management of the plantation matrix through ecological networks. Here, I explore
the use of mesofilters within highly threatened remnant Afro-montane grasslands in
KwaZulu-Natal, South Africa, to optimise biodiversity conservation planning for such
landscapes. As per anecdotal evidence, I used rockiness in the landscape as a possible driver
of species richness and species assemblage variability at the meso-scale, using a multi-taxon
and multi-trophic approach. In this montane landscape, I also examined the effect of elevation
on spatial heterogeneity of taxa. I further examined the functional responses of taxa to
rockiness in the landscape. Rockiness in the landscape significantly influenced the species
richness and assemblage structure of three key grassland taxa: flora, butterflies, and
grasshoppers. I showed that for plants, this response was due to growth forms such as
geophytes and perennial grasses that were more closely associated with rockiness, and
therefore the main contributors to observed differences in the dispersion patterns of flora.
Grasshoppers were not necessarily responding to higher rock exposure per se, but rather
towards the environmental conditions created by rockiness within the landscape, such as
lower vegetation density. For butterflies, certain behavioural traits, such as resting, territorial
behaviour and/or mate-locating behaviour, were more typical in areas of higher rock
exposure. This suggested that rocks are a definite habitat resource to certain butterflies.
Overall, this finding where an abiotic surrogate is representative of key taxa in an ecosystem
is interesting, as cross-taxon surrogacy has been shown to be stronger than surrogates based
on environmental data. Furthermore, taxa responded functionally to rockiness in the
landscape. This thesis therefore supports the idea that environmental surrogates are indeed
useful for biodiversity conservation planning. Furthermore, ecosystems can potentially have many attributes or features that would be of conservation interest, and delineating a set of
mesofilters is a useful way of expressing particular attributes to be used in wildlife
conservation evaluation. The concept of the mesofilter as a practical biodiversity conservation
tool is therefore validated here. I also argue the importance of habitat heterogeneity for
biodiversity conservation planning in this montane grassland landscape. The potential for
optimising the design of landscape configurations such as ecological networks, through
information obtained from the mesofilter, is emphasised. We can safely add another tool in
the biodiversity conservation toolbox of this Afro-montane grassland ecosystem. / AFRIKAANSE OPSOMMING: Bewaringbeplanners gebruik tans baie tradisionele biodiversiteit-bewarings metodes om die
huidige biodiversiteits krisis te help verlig. Tog, die huidige voortdurende verliese in
biodiversiteit wêreldwyd, vra na nuwer en verbeterde metodes van biodiversiteit-bewaring.
Een so ‘n nuwe bewaring metode, is die mesofilter. Mesofilters is biotiese of abiotiese
ekosisteem elemente wat kritiek is tot die welstand van spesies, en daarom veral waardevol is
om variasie in spesies verspreiding in ‘n landskap te help verduidelik. Daarby is die
mesofilter konsep ook komplementêr tot meer tradisioneel gebruike bewaringskonsepte, soos
fyn-filter en breë-filter konsepte. Deur die mesofilter benadering toe te pas in die ontwerp en
bestuur van beskermde areas, bewaareas, of land-spaar initiatiewe, kan ons biodiversiteitbewaring
in ‘n vining ontwikkelende wêreld optimaliseer. Byvoorbeeld, die bosbou industrie
is pro-aktief in hul benadering om biodiversiteit verliese te verminder, deur optimalisering
van die ontwerp en bestuur van ekologiese netwerke in die plantasiematriks. In hierdie tesis,
ondersoek ek die gebruik van mesofilters in hoogs bedreigde oorblyfels Afrikaberg grasvelde
in KwaZulu-Natal, Suid-Afrika, om die bewaringsbeplanning van dié gebiede te optimaliseer.
Vanaf anekdotiese bewyse, het ek spesifiek gebruik gemaak van klipperigheid in die landskap
as ‘n moontlike drywer van spesies-rykheid en spesies-samestelling variasie by ‘n meso-skaal,
deur ‘n multi-takson en multi-trofiese benadering. In hierdie berglandskap, het ek ook die
effek van hoogte bo seevlak op ruimtelike verspreiding van taksa bestudeer. Verder het ek
ook gekyk na die funksionele reaksie van taksa tot klipperigheid in die landskap.
Klipperigheid in die landskap het ‘n beduidende invloed gehad op spesies-rykheid en spesiessamestelling
van drie sleutel grasveld taksa: plante, skoenlappers, en springkane. Ek wys dat
vir plante, hierdie reaksie as gevolg was van spesifieke plantgroeivorme, soos bolplante en
meerjarige grasse, se noue verband met klipperigheid, en daarom, dat hierdie groepe die hoof
bydraers is tot gesiene variasie in plantspesies verspreiding in die landskap. Vir springkane,
was hierdie reaksie nie noodwendig omdat hulle die klippe self gebruik het nie, maar meer as
gevolg van die omgewingskondisies geskep deur verhoogde klipperigheid in die landskap,
soos laer plantegroei digtheid. Vir skoenlappers, was hierdie reaksie tot klippe as gevolg van
sekere gedragskaraktereienskappe, soos rus op klippe, gebied beskerming en/of paarmaat
soektog, wat tipies meer gesien was in klipperige omgewings. Dit dui daarop dat klippe ‘n
definitiewe habitat hulpbron is vir sekere skoenlappers. Oor die algemeen is hierdie
bevinding, waar abiotiese surrogate verteenwoordig is van drie sleutel taksa in ‘n ekosisteem,
baie interessant, siende dat tussen-takson surrogate soms gesien word as sterker as surrogate gebaseer op omgewingsdata. Verder, taksa het funksioneel gereageer teenoor die klippe in die
landskap. Hierdie tesis ondersteun dus die idee dat omgewingssurrogate wel nuttig is vir
biodiversiteit-bewaring beplanning. Ekosisteme mag vele potensiele elemente van bewarings
belang bevat, maar om sulke elemente as ‘n stel mesofilters te klassifiseer, is ‘n nuttige
manier om spesifieke elemente te gebruik in natuurbewarings evaluasie initiatiewe. Gevolglik
word die konsep van die mesofilter as ‘n praktiese biodiversiteit-bewaring gereedskapstuk
hier bevestig. Ek beredeneer ook die belangrikheid van habitat heterogeniteit vir
biodiversiteit-bewaring van hierdie berggrasveld landskap. Die potensiaal vir optimalisering
van ontwerp en bestuur van landskap konfigurasies, soos ekologiese netwerke, word
beklemtoon. Ons kan met veiligheid nog ‘n gereedskapstuk plaas in die biodiversiteitbewarings
gereedskapkis van hierdie Afrikaberg grasveld ekosisteem.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/79892 |
| Date | 03 1900 |
| Creators | Crous, Casparus Johannes |
| Contributors | Samways, Michael J., Pryke, James S., 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 | 122 p. : ill., maps |
| Rights | Stellenbosch University |
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