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Determining sustainable lignocellulosic bioenergy systems in the Cape Winelands District Municipality, South AfricaVon Doderer, Clemens Cornelius Christian 12 1900 (has links)
Thesis (PhD(Agric))--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The energy paradigm shift from fossil fuels to renewable energy sources is driven, among others, by a growing sustainability awareness, necessitating more sophisticated measurements in terms of a wider range of criteria. Technical efficiency, financial profitability, environmental friendliness and social acceptance are some of the factors determining the sustainability of renewable energy systems. The resulting complexity and conflicting decision criteria, however, constitute major barriers to processing the information and decision-making based on the information. Seeking to implement local bioenergy systems, policymakers of the Cape Winelands District Municipality (CWDM), South Africa, are confronted with such a problem.
Following a case study approach, this study illustrates how life-cycle assessment (LCA), multi-period budgeting (MPB) and geographic information systems (GIS) can aid the decision-making process by providing financial-economic, socio-economic and environmental friendliness performance data in a structured and transparent manner, allowing for a comparison of the magnitude of each considered criterion along the life-cycle. However, as the environmental impacts cannot readily be expressed in monetary terms on a cardinal scale, these considerations are given less attention or are omitted completely in a market economy. By measuring the various considerations on an ordinal scale and by attaching weights to them using the multi-criteria decision analysis (MCDA) approach, this study, illustrates how to internalise externalities as typical market failures, aiding policymakers of the CWDM to choose the most sustainable bioenergy system.
Following the LCA approach, 37 lignocellulosic bioenergy systems, encompassing different combinations of type of harvesting and primary transport, type of pretreatment (comminution, drying, and fast pyrolysis) and location thereof (roadside or landing of the central conversion plant), type of secondary transport from the roadside to the central conversion plant, and type of biomass upgrading and conversion into electricity, were assessed against five financial-economic viability criteria, three socio-economic potential criteria and five environmental impact criteria. The quantitative performance data were then, as part of the MCDA process, translated into a standardised ‘common language’ of relative performance. An expert group attached weights to the considered criteria using the analytical hierarchy process (AHP). The ‘financial-economic viability’ main criterion received a weight of almost 60%, ‘socio-economic potential’, nearly 25% and ‘lowest environmental impact’, the remainder of around 16%. Taking the prerequisite of financial-economic viability into consideration, the preferred option across all areas of the CWDM (despite various levels of productivity) comprises a feller-buncher for harvesting, a forwarder for primary transportation, mobile comminution at the roadside, secondary transport in truck-container-trailer combinations and an integrated gasification system for the conversion into electricity. / AFRIKAANSE OPSOMMING: Die energie paradigma verandering van fossielbrandstowwe na hernubare energiebronne word gedryf deur ‘n groeiende klem op volhoubaarheid, wat ook meer gesofistikeerde meting in terme van ‘n wyer verskeidenheid maatstawwe vereis. Tegniese doeltreffendheid, finansiële winsgewendheid, omgewingsvriendelikheid en sosiale aanvaarbaarheid is sommige van die faktore wat die volhoubaarheid van hernubare energie stelsels bepaal. Die verskeidenheid oorwegings bring egter kompleksiteit en konflik mee by die verwerking van inligting en die besluitneming wat daarop berus. Beleidmakers van die Kaapse Wynland Distriksmunisipaliteit wat ten doel het om plaaslik bio-energie stelsels te implementeer, word met hierdie probleem gekonfronteer.
Hierdie ondersoek illustreer aan die hand van ‘n gevallestudie benadering hoe lewensiklus analise, multiperiode begroting en geografiese inligtingstelsels besluitneming kan ondersteun deur die voorsiening van finansieel-ekonomiese, sosio-ekonomiese (indiensneming) en omgewingsvriendelikheid prestasie data op ‘n gestruktureerde en deursigtige wyse. Dit maak die vergelyking van die waardes van al die kriteria by elke fase van die lewensiklus moontlik. Aangesien die omgewingseffekte nie geredelik in monetêre terme op ‘n kardinale skaal gemeet kan word nie, kry hulle binne die markekonomie minder aandag of word selfs buite rekening gelaat. Deur hierdie verskeidenheid kriteria op ‘n ordinale skaal te meet en gewigte met behulp van multikriteria besluitneming aan hulle toe te ken, toon hierdie ondersoek hoe om eksternaliteite as tipiese markmislukkings te internaliseer om beleidmakers van die Kaapse Wynland Distriksmunisipaliteit in staat te stel om die mees volhoubare bio-energie stelsel te kies.
Met behulp van lewensiklus analise is 37 lignosellulose bio-energie stelsels geïdentifiseer as verskillende kombinasies van oes van die bome, primêre vervoer van houtstompe, vooraf verwerking (verspaandering, droging, vinnige pirolise), die ligging van hierdie aktiwiteite (langs ‘n plantasie of by ‘n sentrale omsettingsaanleg), tipe sekondêre vervoer van houtspaanders vanaf die plantasie na die sentrale omsettingsaanleg en tipe biomassa opgradering en omsetting van die houtspaanders na elektrisiteit. Die verskillende stelsels is gemeet aan die hand van vyf finansieel-ekonomiese kriteria, drie indiensneming potensiaal kriteria en vyf omgewingsimpak kriteria. Die kwantitatiewe metings is deur middel van multikriteria besluitneming omgeskakel na ’n gestandaardiseerde “gemeenskaplike taal” van relatiewe prestasie. Lede van ‘n ekspertgroep het gewigte is aan die onderskeie kriteria met behulp van die analitiese hierargie proses toegeken. Aan die finansieel-ekonomiese lewensvatbaarheid hoof kriterium is ‘n gewig van by die 60% toegeken, aan die indiensnemingspotensiaal bykans 25% en aan omgewingsvriendelikheid sowat 16%. Die voorkeur kombinasie vir al die areas van die Kaapse Wynland Distriksmunisipaliteit sluit in ‘n saag-bondelaar vir die oesproses, ‘n plantasie-vragmotor vir primêre vervoer, mobiele verspaandering langs die plantasie, ‘n vragmotor-skeepshouer-treiler kombinasies vir die sekondêre vervoer van houtspaanders en ‘n geïntegreerde vergassingstelsel vir die omsetting van houtspaanders na elektrisiteit.
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Evaluating the returns to research on a project level : cover crops in the South African wine industryMorgan, John (John Idwal) January 1999 (has links)
Thesis (MScAgric)--Stellenbosch University, 1999. / ENGLISH ABSTRACT: The purpose of the study is to determine the rate of return to cover crop research in the
wine industry. The method followed will prove an invaluable contribution toward the
need to determine a suitable approach for evaluation studies. The importance behind such
a study is the development of appropriate ex ante evaluation approaches, which will assist
in the allocation of public research resources in both a social and economical manner.
The wine industry is currently enjoying healthy international demand, but will need to
remain competitive to reap the full benefit of international exposure. The need therefore
exists for a continuation of research at the institutional level, in order to maintain the
progressive nature of research knowledge that was available in the past. The evaluation of
ex post and ex ante research will assist in maintaining government funding for research
and help with campaigning for private investment of research in the wine industry.
The use of two evaluation approaches was used for the analysis. Firstly, the production
function approach achieved a rate of return of 44 percent, using weather and research
expenditure as a means to explain the variations in wine grape yield. Secondly, a cost
benefit approach was devised in order to make a direct comparison between the cost and
benefits related to the cover crop research. The rate of return achieved for this mode of
analysis is 37 percent, using trial plot data as a source of information on potential
benefits. In addition to this the cost benefit approach was used to show the difference in
rate of return that is achievable between two growing regions. The variable that exists
between the two regions, is the higher rate of irrigation in one of the regions.
The high rate of return achieved for the investment, provides suitable motivation for the
increase in state funding for research in the wine industry, and provides valuable
information for the enticement of support by private investors. The two methods used in
the study will both draw a certain amount of criticism, largely as a result of the lack of available data. The empirical nature of the approaches is however simple and applicable
down to the project level. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie is om die opbrengs op navorsing oor dekgewasse in die Suid-
Afrikaanse wynbedryf te bepaal. Hierbenewens het die studie dit ook ten doel om gepaste
metodieke vir die evaluering van navorsingsprojekte daar te stel. In hierdie opsig maak
hierdie studie ' n bydrae tot besluitneming oor die allokering van openbare fondse vir
landbounavorsing op 'n ekonomies en sosiale optimale wyse.
Die Suid- Afrikaanse wynbedryf beleef tans ' n bloeifase, hoofsaaklik as gevolg van sterk
internasionale vraag na sy produkte, maar salop sy internasionale mededingendheid moet
let indien die volle voordele hiervan benut kan word. Daarom is dit noodsaaklik dat die
bedryf op tegnologiese gebied moet kan meeding, en dus dat navorsingsbesteding nie
onoordeelkundig ingekort word rue. Inligting oor die opbrengs op navorsingsbesteding is
dus noodsaaklik om die volgehoue betrokkenheid van die staat te kan regverdig, hetsy as
finansier of as katalisator vir privaatsektor betrokkenheid.
In hierdie studie is die opbrengs op navorsing gemeet deur beide die bekende
produksiefunksie benadering sowel as deur koste-voordeel ontleding. In die eerste geval
is 'n opbrengskoers van 44% gemeet, en in die tweede geval is dit 37%. By die kostevoordeel
ontleding is ook 'n verdere onderskeid gemaak tussen twee wynbou-streke om
die invloed van meer besproeiing te bepaal.
Ten spyte van dataprobleme, veral wat betref die koste van navorsing, kan beweer word
dat die inligting so verkry van nut sal wees vir besluitnemers by die toekenning van
skaars navorsingsfondse, asook by bedinging om privaatsektor fondse.
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An economic evaluation of the winelands health worker programmeRörich, Eben Eugéne 12 1900 (has links)
Thesis (MComm)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Historically health care in South Africa has been an area of great inequity. Health
care was inequitable, inadequate and racially based. In order to redress the gap in the
delivery of health care services, created by the previous dispensation of separate
development, the National Department of Health has adopted a Primary Health Care
(PHC) approach as the guiding principle for the reconstruction of the health system in
South Africa. One of the pillars of this approach is the empowerment of communities
to participate, thus moving from facility based- to community based health care.
The aim of the National Health System (NRS) is to promote health and health
knowledge, to provide an equitable, accessible, and appropriate health service, and to
empower people to take greater responsibility for their own health. It is constructed
around the belief that health for all cannot be achieved simply by improving the
formal health system, but that a holistic and multi-sectoral approach is required.
This thesis explores the community health worker (CRW) as a possible cost-effective
and efficient supplementary service, to the current formal health system, to bridge the
gap in the formal health system through the provision of PHC services in a rural
setting. This was done through the economic evaluation of a CHW programme
operating in the Winelands are of the Western Cape.
The aim of this study was to evaluate and analyse the nature, performance, and costs
of the programme and place it in context by comparison to other similar programmes.
This comparison focused on physical characteristics, goals, and cost structures. It
also aims to measure the direct and indirect impact of this type of intervention on the
agribusiness sector as well as the local health authorities. The evaluation proceeded
from the premise that the CHW programme, if implemented correctly with proper and
appropriate training, and adequate post training support, will be a cost-effective and
efficient model for the provision ofPHC services in this rural/farming area.
The economic evaluation of this CHW programme required it to be viewed from two
perspectives. The first component viewed the implementation of the programme from
the perspective of the agribusiness sector. This aspect of the study included both a qualitative as well as a quantitative VIew of the costs, benefits (perceived or
otherwise), and perceptions of the CHW intervention. The second component
assessed the CHW programme within the context of a resource constrained public
sector health budget. Since the implementation of this programme implies certain
expenditures on the part of the local health authorities, these cost had to be identified
and quantified to gauge the effectiveness of that expenditure. / AFRIKAANSE OPSOMMING: Geskikte en doeltreffende gesondheidsdienste in Suid-Afrika se onlangse geskiedenis
was nog gereserveer vir 'n uitgesoekte groep mense. Die gesondheidstelsel was
ontoereikend, onvoldoende en gebaseer op ras. Daar het 'n gaping ontstaan tussen die
dienste wat gelewer is en die werklike behoeftes van die mense wat dit moes gebruik.
Ten einde hierdie gaping aan te spreek het die Nasionale Departement van
Gesondheid besluit om 'n Primêre Gesondheidsorg (PRe) benadering te volg wat
klem plaas op die bemagtiging van plaaslike gemeenskappe deur deelname. Dit was
'n duidelike skuifvanaffasiliteit- na gemeenskap gebaseerde gesondheidsdienste.
Die oorkoepelende doel van hierdie verskuiwing in fokus was om voorheen
benadeelde gemeenskappe voldoende toegang te gee tot gesondheidsdienste en ook
om hierdie dienste aan te pas by die behoeftes van sodanige gemeenskappe.
Hierdie tesis ondersoek die Wynland distriksraad se Gemeenskap Gesondheidswerker
Program as 'n moontlike koste-effektiewe stelsel vir die lewering van toepaslike
primêre gesondheidsdienste in landelike areas. Die doel van die studie was die
sistematiese ontleding van die werking en omvang van, en die kostes verbonde aan
die implementering en onderhoud van hierdie program. Die studie poog om die
impak van hierdie program op die formele landbou sektor asook die plaaslike
gesondheidsowerhede te identifiseer en, waar moontlik en prakties wenslik, te
kwantifiseer.
Die ondersoek sluit in die stelselmatige ontleding van kostes en voordele vir die
formele landbou sektor sowel as die plaaslike gesondheidsowerhede. Die kostes
asook die kliniese uitkomste geassosieer met die implementasie van die
Gesondheidswerker program sal dan in konteks geplaas word deur dit te vergelyk met
ander soortgelyke programme wat in die verlede aangepak is. Die vergelyking sal
fokus op die fisiese eienskappe, koste struktuur, bronne van ondersteuning en die
primêre doel van die intervensie.
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Assessing risk in the Paarl/Berg River region by means of various portfolio diversification modelsMaritz, Gerrit 12 1900 (has links)
On t.p.: Masters of Agricultural management. / Thesis (MAgricAdmin)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The need to take account of risk in agriculture must be part of every decision taken in
agriculture. Yet risk is nothing to be too afraid of Risk is a choice rather than a fate.
The actions we dare to take, which depend on how free we are to make choices, are what
the theory of risk is all about. The task is rather to manage risk effectively, within the
capacity of the farmer, business or group in order to withstand adverse outcomes. Some
methods of managing risks are feasible for all types of farms. Others are only feasible for
certain sizes and types of farms. Therefore, farmers in general need a systematic
technique that will enable them to choose an efficient investment strategy from among all
feasible strategies. Specifically, given n risky assets (such as the different enterprises in
the PaarlIBerg River region), it is essential to seek a diversification strategy which yields
a portfolio lying on the efficient frontier.
The research question was whether different diversification models (Markowitz
diversification model, Single Index Model and the Capital Asset Pricing Model) that are
normally applied in capital markets for the construction of optimal diversified portfolios
consisting out of different shares, are also applicable on risky portfolios in agriculture
comprising different enterprises in the PaarlIBerg River region.
The efficient frontier can be seen as the graphical representation of a set of portfolios that
maximize expected return for each level of portfolio risk. The Microsoft Excel portfolio
optimiser (SOLVER) programme was used to illustrate the investment proportions,
expected returns, and standard deviations of the portfolios ofthe efficient frontier.
The Single Index Model (SIM) can be used as an alternative to Markowitz diversification
model. It drastically reduces the number of parameters needed to be estimated and yields
the efficient set relatively easily without the technical difficulties characterising the fullrank
solution. However, if the SIM assumptions are in contradiction to the actual data,
the simplification of the calculations is achieved at the cost of getting imprecise results.
The simplicity of SIM calculations was attained at a cost of constructing a sub-optimal
portfolio, which does not lie on the corresponding efficient frontier.
The Capital Asset Pricing Model (CAPM) reveals that there is a great deal of systematic
risk in relation to the portfolio enclosed in this study. By using the CAPM it is possible
to determine which part of the risk the producer can control (non-systematic risk) and
which part the producer has no control over (systematic risk). The proportions of
systematic risk that can be diversified away are small, relative to the total risk of the
Farm Sector Portfolio.
The success of these models depends on the efficiency of the market, as weU as a large,
up-to-date and reliable data source. Many younger cultivars could not be included in this
study, due to the limited availability of data. In the next few years as data become
available, it will be possible to construct efficient frontiers out of a wider range of
enterprises. Different enterprises and cultivars will increase the number of alternative
uses for natural resources in the PaarlIBerg River region through diversification. This
will result in more choices for the farmer, and more flexibility in the decision-making
process. Without reliable data, the result will be "garbage in, garbage out." / AFRIKAANSE OPSOMMING: In elke besluit wat geneem word in landbou moet risiko as 'n faktor in ag geneem word.
Tog is risiko nie iets om te vrees nie. Dit is eerder keuse as noodlot. Die stappe wat ons
waag om te neem, wat afhang van hoe vry ons is om keuses te maak, is waaroor die teorie
van risiko gaan. Die doel van die tesis is om risiko effektief te bestuur binne die
vermoëns van die boer om sodoende negatiewe resultate die hoof te bied Sommige
metodes van risikobestuur is lewensvatbaar vir alle soorte plase. Ander is slegs
lewensvatbaar vir sekere groottes en tipes plase. Daarom benodig boere in die algemeen
'n tegniek wat dit vir hulle moontlik maak om 'n effektiewe beleggingstrategie te kies uit
die verskillende uitvoerbare strategiee. Gegewe n as riskante aktiwiteite (soos die
verskillende gewasse in die PaarllBergrivierstreek) is dit noodsaaklik om 'n
diversifiseringstrategie te vind wat 'n portefeulje sal lewer wat raak aan die effektiewe
grens.
Die navorsingsvraag was of verskillende diversifiseringsmodelle (Markowitz
diversifiseringsmodel (MVC), "Single Index Model" (SIM) en die "Capital Asset Pricing
Model" (CAPM)) wat gewoonlik toegepas word in kapitaalmarkte vir die samestelling
van optimale gediversifiseerde portefeuljes bestaande uit verskillende aandele, ook van
toepassing sal wees op riskante portefeuljes in die landbou in die PaarlJBergrivierstreek,
wat verskillende gewasse insluit.
Die effektiewe grens kan gesien word as die grafiese voorstelling van 'n stel portefeuljes
wat die verwagte winste vir elke vlak van portefeuljerisiko vermeerder. Die Microsoft
Excel portefeulje optimeringsprogram (SOLVER) word gebruik om die beleggingsverhoudings, verwagte winste en standaardafwykings van die portefeuljes aan
die effektiewe grens te illustreer.
Die "Single Index Model" (SIM) kan gebruik word as 'n alternatief vir die Markowitz
diversi:tikasiemodel. Dit verminder drasties die getal parameters en lewer maklik die
effektiewe reeks, sonder die tegniese probleme wat ondervind word met die oplossing by
die Markowitz model. Nietemin, indien die SIM die werklike data weerspreek sal die
vereenvoudiging van die berekenings bereik word ten koste van onakurate resultate. Die
eenvoud van die SIM is verkry ten koste van die samestelling van 'n suboptimale
portfeulje, wat nie aan die ooreenstemmende effektiewe grens lê nie.
Die "Capital Asset Pricing Model" (CAPM) wys dat daar baie sistematiese risiko
gekoppel is aan die portfeulje ingesluit in hierdie studie. Deur gebruik temaak van die
CAPM is dit moontlik om vas te stel watter deel van die risiko (nie-sistematies) die
produsent kan beheer en watter deel die produsent nie kan beheer nie (sistematiese
risiko). Die verhouding van sistematiese risiko wat weggediversifiseer kan word is klein
in verhouding tot die algehele risiko van die boerderysektor portefeulje.
Die sukses hang afvan die doeltreffendheid van die mark, sowel as 'n groot tot-op-datum
en betroubare bron van data. Baie van die jonger aangeplante kultivars kan nie ingesluit
word in hierdie studie nie as gevolg van beperkte data In die volgende paar jaar, soos
data beskikbaar word, sal dit moontlik wees om effektiewe grense van 'n wye reeks
gewasse saam te stel. Verskillende gewasse en kultivars sal die hoeveelheid alternatiewe
gebruike van natuurlike hulpbronne in die PaarllBergrivierstreek vermeerder deur
diversifikasie. Dit sal lei tot meer keuses vir die boer en meer buigsaamheid in die
besluitnemingsproses. Sonder betroubare data kan betroubate resultate nie verkry word
me.
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Seed ecology as a determinant of population structure in some Southern African Savanna Acacia speciesWalters, Michele 12 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: African Acacia species are often major contributors to the progressive increase in the woody
component of savannas, a phenomenon commonly referred to as bush encroachment. In Hluhluwe-
Umfolozi Park, the numbers of adult Acacia nilotica (L.) Willd. Ex Del. trees per hectare far
exceed (by III) that of A. karroo Hayne adults. The relative dominance is reversed in the juvenile
stage with A. karroo (725 ha') outnumbering A. nilotica (225 ha-I) threefold outside closed
woodlands. African acacias produce large quantities of seed and may have large soil-stored seed
banks. They suffer pre-dispersal predation by bruchid beetles and may be either wind or animal
dispersed. Once dispersed they are vulnerable to post-dispersal attack.
This study tested several hypotheses regarding various aspects of seed ecology of A. karroo
and A. nilotica. The null hypothesis that seed ecology does not contribute to the success of A.
karroo over A. nilotica, was tested.
Acacia karroo trees were smaller (mean basal diameter: 7.8 cm) than A. ni/otica trees
(mean basal diameter: 18.5 cm) on average, but produced more seeds (A. karroo mean: 1628; A.
nilotica mean: 992) for a given basal diameter size class. It was found that A. karroo showed less
bruchid infestation (mean: 1.36-3.81%) than A. nilotica (mean: 14.67-86.70%) at all stages of pod
development with a proportion of A. karroo seeds (7.1 %) being able to germinate after bruchid
attack. Bruchid attack rendered A. ni/otica seeds unviable. There was no difference between the
two species with regards to the soil-stored seed bank and the viability of seeds found in the soil.
Acacia karroo showed higher germination levels (5.1%) and better establishment (4.9%) than A.
nilotica (1.5% and 0.4% respectively). On average, there was no difference in germination levels
between burnt and unbumt seeds, but there was a significant difference in germination of burnt
seeds in both burnt (4.5%) and unbumt (2.5%) sites and unbumt seeds in both burnt (2.8%) and
unbumt (4.9%) sites when considered separately.
Post-dispersal predation of A. karroo seeds (21.8%) was higher than that of A. nilotica
(12.7%). There was more rodent predation in tall grass areas (26.0%) than short grass (10.7%) or
canopy areas (15.2%), and most seeds were lost from unprotected control groups. Rodent presence
was a significant factor in unexplained seed disappearance.
The ability of A. karroo to germinate easily and the low levels of beetle predation
experienced by this species seemed to be its main advantage over A. nilotica as an encroaching
species in Hluhluwe-Umfolozi Park. / AFRIKAANSE OPSOMMING: Die Acacia spesies van Afrika is dikwels belangrike bydraers tot die progressiewe toename
in die houtkomponent van savannas. Hierdie verskynsel word algemeen na verwys as
bosindringing. In die Hluhluwe-Umfolozi Park is die aantal volwasse Acacia nilotica (L.)
Willd. Ex Del. bome per hektaar aansienlik meer (l l l meer) as die aantal volwasse A.
karroo Hayne bome. In die jong stadium is die oorheersing omgekeerd, met driekeer soveel
A. karroo (725 ha-I) as A. nilotica (225 ha-I) bome buite beboste gedeeltes.
Afrika se Acacia spesies produseer groot hoeveelhede saad en kan oor aansienlike
grond-gebergde saadbanke beskik. Voor verspreiding word die saad aan predasie deur
bruchid-kewers blootgestel. Die saad kan óf deur wind óf diere versprei word en na
verspreiding word dit ook aan predasie blootgestel.
Hierdie studie het verskillende hipoteses rakende verskeie aspekte van die
saadekologie van A. karroo en A. nilotica getoets. Die nulhipotese dat saadekologie nie tot
die groter sukses van A. karroo teenoor A. nilotica bydrae nie, is getoets.
Acacia karroo bome was oor die algemeen kleiner (gemid. basale omtrek: 7.8 cm)
as A. nilotica (gemid. basale omtrek: 18.5 cm) bome maar het meer saad (A. karroo gemid.:
1628; A. nilotica gemid.: 992) per gegewe basale diameter grootte klas gelewer. Daar is
geen verskil tussen die twee spesies rakende grondgebergde saadbanke en die
lewensvatbaarheid van hierdie saad gevind nie.
Acacia karroo het hoër vlakke van ontkieming (5.1%) en beter vestiging (4.9%) as
A. nilotica (l.5% en .4% respektiewelik) getoon. Daar was oor die algemeen geen verskil in
die ontkiemingsvlakke van gebrande en ongebrande sade nie, maar wel 'n beduidende
verskil in die ontkieming van gebrande sade in beide gebrande (4.5%) en ongebrande
(2.5%) areas en ongebrande sade in gebrande (2.8%) en ongebrande (4.9%) areas as dit
afsonderlik geëvalueer is.
Die predasie van A. karroo saad na verspreiding (21.8%) was hoër as dié van A.
nilotica (12.7%). Daar was meer knaagdier-predasie in gebiede met lang gras (26.0%) as
dié met kort gras (10.7%) of boomryke gedeeltes (15.2%). Die meeste saad is in
onbeskermde kontrolegroepe verloor. Die teenwoordigheid van knaagdiere het 'n
belangrike rol in die onverklaarde verdwyning van saad gespeel.
Dit is gevind dat A. karroo se vermoë om maklik te ontkiem, asook die lae vlakke
van insek skade aan die saad, die belangrikste voorsprong is wat dié spesie oor A. nilotica
as 'n indringer in Hluhluwe-Umfolozi Park het.
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