Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Biofuels are being promoted as a global necessity to meet climate change targets
through the replacement of fossil fuels. Many countries have identified biofuels as a
potential mechanism to meet these challenges, with policy directives driving biofuel
production. The South African government has proposed that biofuels form part of the
country’s future renewable energy and has proposed a draft biofuel strategy. This study
aims to investigate appropriate approaches to determine potential biodiversity impacts
from biofuel production.
Since biofuels are not currently grown to any large extent in South Africa, impact was
modelled using future scenarios of converting available land within the Eastern Cape
Province of South Africa. Suitable species were identified using the species distribution
modelling programme MaxEnt. Some of the proposed biofuel crops were considered as
invasive (i.e. they spread from sites where they are cultivated) or are very likely to be
invasive in South Africa. This study also highlighted the considerable overlap between
suitable growing areas and areas considered important for future biodiversity
conservation. The biodiversity intactness index (BII), a broad based biodiversity indicator, was used
to assess the biodiversity implications of transforming available land to biofuels. The BII
indicates losses of biodiversity between 17.6% and 42.1% for the land use scenarios
identified. An important finding was that excluding important biodiversity areas that
occur outside of protected areas can reduce biodiversity losses by as much as 13% and
maintain an overall intactness of ~70%. Currently the BII does not account for
fragmentation or landscape configuration. This was addressed by developing a revised
biodiversity intactness index (R-BII) which included the effect of patch-size and habitat
fragmentation on biodiversity intactness. This study found that although the original BII
reported on the biodiversity trends of large-scale shifts in land-use across multiple
scales it could not detect changes in landscape configuration which was reflected by the
R-BII.
Land-use change can impact on ecosystem processes that underpin the provisioning of
ecosystem services by changing the combinations of species and the plant functional traits within communities. The impacts of cultivating potential biofuel species (Acacia
mearnsii, Sorghum halepense and Eucalyptus species) were investigated using a plant
functional traits approach. These species were shown to affect the leaf nitrogen content,
leaf phosphorous content and leaf dry matter content associated with important
ecosystem functions within an ecosystem service hotspot in the Eastern Cape. A decline
in functional diversity was reported for all transformed land-uses by as much as ~40%.
These shifts may be used to identify potential changes to ecosystem services associated
with natural vegetation.
The methods used in this thesis highlight the overall relevance of this work and its
importance to minimising biodiversity resulting from biofuel production. Some of the
key findings address resolving spatial conflict, using biodiversity indicators, assessing
impacts of potential invasive species and planning for ecosystem services. New drivers
of change to land-use, such as biofuel production, are a major challenge to conservation
biologists and planners and the insights derived in from this study can be successfully
applied to guide biofuel production. / AFRIKAANSE OPSOMMING: Biobrandstof word internasionaal beskou as 'n noodsaaklike komponent in die
bereiking van klimaatsverandering doelwitte deur fossielbrandstowwe daarmee te
vervang. Daarom word biobrandstof deur verskeie lande geïmplementeer as 'n
potensiële meganisme om aan hierdie uitdaging te voldoen. Die Suid-Afrikaanse
regering het voorgestel dat biobrandstof deel vorm van die land se hernubare energie
toekoms en het daarom 'n konsep biobrandstofstrategie voorgestel. Die aanvaarding
van so 'n strategie sal waarskynlik ‘n aantal verreikende gevolge inhou. Hierdie studie
gebruik verskeie benaderings ten einde die impak van biobrandstof produksie op
biodiversiteit te bepaal.
Aangesien biobrandstof nie tans ‘n beduidende bydra maak tot tradisionele
brandstofproduksie in Suid-Afrika nie, word die impak daarvan geskoei op die
omskakeling van beskikbare grond. Die Oos-Kaap provinsie van Suid-Afrika speel a
sleutelrol in hierdie opsig en vorm daarom die fokus van hierdie analise. Geskikte
spesies is geïdentifiseer deur die sagtewareprogram, MaxEnt, waardeur
spesiesverspreiding gemodelleer word.
Hierdie studie beklemtoon die aansienlike oorvleueling wat daar bestaan tussen
geskikte aanplantingsgebiede en belangrike biodiversiteitsareas wat nie tans formeel
bewaar word nie. Sommige van die voorgestelde biobrandstofgewasse is tans
indringers, of het die potensiaal om indringerplante te word en daarom is daar
toenemende kommer oor die kweek van biobrandstof gewasse in Suid-Afrika. Die
“Biodiversity Intactness Index” (BII), 'n algemene biodiversiteitsaanwyser, is gebruik
om die implikasies van grondomskakeling na biobrandstof op biodiversiteit te evalueer.
Die BII dui op verliese van tussen 17,6% en 42,1% vir die grondgebruikscenario's wat
geïdentifiseer is. 'n Belangrike bevinding was dat die uitsluiting van belangrike biodiversiteitsareas buite beskermde gebiede die verlies van biodiversiteit met soveel
as 13% kan verminder en biodiversiteit eenheid van ~ 70% kan behou. Die BII maak
egter nie tans voorsiening vir landskap fragmentasie nie. ‘n “Revised-Biodiversity
Intactness Index” (R-BII) is ontwikkel wat die effek van kol-grootte en habitat op
biodiversiteit eenheid insluit. Hierdie studie het bevind dat alhoewel die oorspronklike BII grootskaalse verandering in die grondgebruik op verskeie skale aandui, dit egter nie
verandering in landskapsamestelling kon opspoor soos die R-BII nie.
Ten slotte, die impak van die aanplanting van potensiële biobrandstofspesies (Acacia
mearnsii, Sorghum halepense en Eucalyptus spesies) op biodiversiteit is ondersoek deur
‘n plant funksionele eienskappe benadering te gebruik. Daar is bevind dat hierdie
spesies die stikstof, fosfor en droë materiaal inhoud van blare verander wat geassosieer
word met belangrike ekosisteem funksies binne 'n biodiversiteit brandpunt in die Oos-
Kaap. ‘n Vermindering van funksionele diversiteit van soveel as ~ 40% is binne alle
omgeskakelde grondgebruike gevind. Hierdie skuiwe kan gebruik word om potensiële
veranderinge van ekosisteemdienste te identifiseer en benadruk ook die potensiële
impak van uitheemse spesies.
Die metodes wat gebruik word in hierdie studie beklemtoon die relevansie van die werk
asook die belangrikheid daarvan om die nadelige uitwerking van
biobrandstofproduksie op biodiversiteit te minimaliseer. Verskeie benaderings tot die
oplossing van ruimtelike konflik, die gebruik van biodiversiteitaanwysers, die
beoordeling van die impak van die potensiële indringerspesies en die beplanning vir
ekosisteemdienste. Nuwe dryfvere van grondgebruikverandering soos biobrandstof is
'n groot uitdaging en die insigte wat uit hierdie studie verkry is dra by tot die
vermindering van die potensiële impak van biobrandstofproduksie op biodiversiteit.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/95933 |
| Date | 12 1900 |
| Creators | Blanchard, Ryan |
| Contributors | Richardson, David M., O Farrell, Patrick J., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xvii, 183 p. : ill. |
| Rights | Stellenbosch University |
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