| Summary: | Thesis (PhD)--Stellenbosch University, 2013. === ENGLISH ABSTRACT: The challenge of conserving biodiversity is daunting. Despite some local conservation gains,
most indicators of the condition of global biodiversity show declines since the 1970’s, while
indicators of the threats to biodiversity all show increases. Humanity has in part responded
to the global biodiversity extinction crisis by establishing protected areas (PA) and they are
widely considered cornerstones of conservation.
However, their efficacy in maintaining biodiversity is much debated. Previous studies have
been unable to provide a general answer because of their typically restricted geographic
and/or taxonomic focus, or qualitative approach. Using a global meta-analysis with 861 pairwise
comparisons inside and outside PAs from 86 studies across five major taxon groups, I
tested the hypothesis that PAs achieve significant conservation outcomes measured as
higher biodiversity values compared with alternative land covers. I found that globally, PAs
typically contain higher abundances of individual species, higher assemblage abundances
and higher species richness. Variation in effect sizes among taxa nonetheless underscores
that PA efficacy can be context specific.
To examine factors driving the context specific nature of PA efficacy, an exact distance,
timed point count methodology was used to assess PAs ecological effectiveness in terms of
bird assemblages of the Kruger National Park (KNP), South Africa, in the Phalaborwa section.
Bird assemblages inside the KNP were compared to matched sites in rural and urban land
cover, as well as the connecting habitat matrix outside the KNP. Species richness and
abundance were significantly lower inside the KNP compared to other land covers. However,
the species assemblages are markedly different. The artificial addition of resources in an
otherwise resources poor area, mainly in terms of gardening, provide suitable habitat for a
range of species, consistent with the more individuals hypothesis. Large-bodied and ground
nesting species are virtually absent outside the KNP. Thus species richness and abundance
differences between land cover regions mask insidious changes in species traits.
Nonetheless, not formally protected land can contribute positively to the regional
biodiversity portfolio.
Since an understanding of the mechanisms that structure species assemblages can aid in the
consequences of anthropogenic drivers disentangling them, I describe and analyse the body
size frequency distributions (BSFDs) of avian assemblages at several spatial scales in the Afrotropical biogeographic realm. I found that the African avifaunal continental BSFD is
unimodal and right-skewed. African avifaunal BSFDs are quantitatively dissimilar to the
African mammal BSFDs, which are bimodal at all spatial scales. Much of the change in
median body size with spatial scale can be captured by a range-weighted null model,
suggesting that differential turnover between smaller- and larger-bodied species might
explain the shift in the central tendency of the BSFD.
My results for the first time quantitatively demonstrate that PAs are a vital component of a
global biodiversity conservation strategy. However, I also show that PA ecological
effectiveness can be context specific, and understanding which species traits are at risk
outside of PAs is critical to predicting their efficacy. === AFRIKAANSE OPSOMMING: Dit is ‘n uitnemende uitdaging om biodiversiteit te bewaar. Ten spyte van sommige sukses op
‘n lokale skaal, dui die meeste indikators aan dat die toestand van globale biodiveristeit
afgeneem het vanaf die 1970’s, terwyl bedreigings daartoe toegeneem het. Die mensdom
het gedeeltelik reageer op die biodiversiteits uitsterfings krisis deur die uiteensetting en
instandhouding van bewaringsgebiede (BG). Hierdie metodiek word wêreldwyd geag as ‘n
hoeksteen van bewaring.
Die ekologiese doeltreffendheid van BG word egter baie debateer. Vorige studies was
geografies beperk of het net op sekere takson groepe gefokus. Vorige studies is ook tipies
statisties kwalitatief van aard. As gevolg daarvan het ek ‘n globale meta-analiese gebruik,
wat bestaan het uit 861 gepaarde meetings vanaf 86 studies, oor vyf verskillende
taksonomiese groepe. Ek het die hipotese getoets dat BG statisties beduidende bewaring laat
gekiet in terme van hoër biodiveristeits waardes binnekant hul grense, in kontras met areas
buite BG. Ek het gevind dat BG juis hoër waardes van hoër indivuduele spesies hoeveelhede,
gemeenskaps hoeveelhede en spesiesrykheid bevat. Tog dui die variasie in effek grootte
onder takson groepe aan dat BG effektiwiteit konteks spesifiek is.
Aangesien BG effektiwiteit konteks spesifiek is, het ek verder ‘n tydstip, eksakte-afstand punttelling
metodiek gevolg om die Kruger Nationale Park (KNP) in Suid Afrika, se ekologiese
doeltreffendheid te bepaal. Ek het voëlgemeenskappe binne KNP vergelyk met voëlgemeenskappe buite KNP. Metings is buite die KNP gedoen in tuislande, die stadsgebied
van Phalaborwa, asook in die habitat matriks wat die areas verbind. Beide spesiesrykheid en
hoeveelheid is hoër buite KNP, maar die voëlgemeenskap struktuur tussen gebiede verskil
noemenswaardig. Die uitbreiding van bronne ten opstigte van nesmaak en voeding (meestal
deur tuinmaak), bied vir voëls goeie habitat in die stadsgebied, soos verwag kan word uit die
meer individue hipotese. Hierdie veranderinge in spesiesrykheid tussen die verskillende areas
versteek veranderinge in die spesies einskappe. Voëls met groot liggaamsmassa, veral die
wat op die grond nes maak, kom in baie minder getalle voor buite KNP. Tog bied onbewaarde
areas ‘n positiewe inpak tot die omgewing se biodiversiteit.
‘n Holistiese begrip van die meganismes wat spesies gemeenskappe struktureer kan help om
die menslike invloed daarop uit te lig. Daarvolgens beskryf ek die liggaamsmassa frekwensie
verspreiding (LMFV) oor verkillende skale in die Afrotropies biografiese streek. Ek het bevind
dat Afrika se voëlgemeenskappe op die kontinentale skaal unimodaal en regs-geskewe is.
Afrika se voël LMFV is beduidend verskillend van Afrika soogdier LMFV, wat bimodaal is op
verskeie skale. Baie van die verandering in mediaan liggaams massa oor verskillende skale
kan verduidelik word met ‘n verspreidings-aangepaste nul-model, wat voorstel dat die
verskille in omset van voëls met of klein, of groot liggaamsmassa in die landskap die
veranderings in LMFV verduidelik.
My studie is die eerste van sy soort wat kwantitatief bepaal dat die gebruik van BG krities is
tot ‘n globale bewaringsstrategie. Verder het ek bewys dat BG se ekologiese doeltreffendheid
afhang van die kontkes op ‘n lokale skaal, en dat spesies eienskappe geïnkorporeer moet
word om BG se doeltreffendheid te bepaal.
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