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A comparison of selected satellite remote sensing techniques for mapping fire scars in limestone fynbosSmit, Walter J. (Walter Johan) 12 1900 (has links)
Thesis (MA.)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: There are many reasons to conserve fynbos. Not only does fynbos form part of the
Cape floral kingdom, one of the richest floral kingdoms in the world, but the
contribution that it makes to the regional economy through utilisation, education,
recreation and tourist opportunities is immeasurable.
Fire plays an integral role in fynbos ecosystems. According to Van Wilgen,
Richardson & Seydack (1994: 322) " ... managing fynbos equates to managing fire".
Therefore managers need accurate fire information about a fynbos area to manage it
properly. This is where satellite remote sensing can provide the manager with useful
information about the fire regime. In other words, satellite remote sensing can help a
manager establish where and when an area has burnt.
Using readily available satellite data, this study attempts to establish (through
comparison) what techniques would be most suitable and affordable to compile a fire
information database. Landsat Thematic Mapper data from 1990 - 1996 of the southwestern
Cape was used and compared with existing fire records of the area.
The results show that techniques such as supervised and unsupervised classification
are reliable in identifying burnt areas, but a major drawback of these techniques is that
they require a large amount of user input and knowledge. They are thus not regarded
as simple or easily repeatable. -
The' more simple techniques like image differencing and image ratioing were also
found to be reliable in identifying burnt areas. These techniques require less user input
and in some instances less data (image bands) to produce similar (or better) results
than supervised and unsupervised classification techniques.
The results show that differencing temporally different Images, obtained from
applying principle components analysis, produces reliable results with very little
confusion and little user input. Using such a technique could enable users to procure
only two bands of Landsat data and still produce reliable fire information for
managing a fynbos ecosystem. / AFRIKAANSE OPSOMMING: Daar is verskeie redes waarom fynbos bewaar moet word. Nie net vorm dit deel van
een van die rykste blommeryke in die wereld nie, maar die bydrae wat dit tot die
streeksekonomie maak, deur die benutting van veldblomme en die geleenthede wat dit
bied vir toerisme en ontspanning, is enorm.
Vuur speel 'n belangrike rol in die bestuur van fynbos ekosisteme. Soos beklemtoon
deur Van Wilgen, Richardson & Seydack (1994: 322) se stelling: " ... managing
fynbos equates to managing fire". Om hierdie rede is dit belangrik dat 'n bestuurder
akkurate inligting oor die verspreiding van veldbrande moet he. Satellietafstandwaarneming
kan hier 'n belangrike rol speel deur sulke inligting te verskaf
Deur gebruik te maak van maklik bekombare satellietdata, poog hierdie studie om te
bepaal (d.m.v. vergelyking) watter tegnieke die mees geskikte is in terme van
bekostigbaarheid en gebruikersvriendelikheid. Landsat Thematic Mapper data van
1990 tot 1996 van die suidwes-Kaap is gebruik en vergelyk met bestaande branddata
van die studiegebied.
Daar is gevind dat tegnieke soos gerigte en nie-gerigte klassifikasie in staat is om
gebrande dele betroubaar uit te ken. Hierdie tegnieke verg egter baie insette en kennis
van die gebruiker en is ook nie maklik om jaar na jaar te herhaal nie. Daarom word
hierdie tegnieke nie aanbeveel nie.
Daar is gevind dat die eenvoudiger tegnieke soos veranderingsanalise ook gebrande
dele betroubaar kon uitken. Hierdie tegnieke het die voordeel dat die gebruiker nie
baie' kennis van die gebied hoef te he nie en ook nie so baie insette hoef te lewer nie.
Hierdie tegnieke word bo gerigte en nie-gerigte klassifikasie aanbeveel. -
Die resultate dui daarop dat betroubare resultate verkry kan word deur tempo reel
verskillende beeIde, verkry deur hoofkomponentanalise, van mekaar af te trek.
Hierdie tegniek vereis relatief min gebruikersinsette en daar kan selfs met slegs twee
Landsat bande gewerk word. So 'n tegniek kan beslis 'n bekostigbare en effektiewe
manier wees om nodige inligting vir die bestuur van 'n fynbos ekosisteem te bekom.
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Botanical inventory and phenology in relation to foraging behaviour of the Cape honeybees (Apis Mellifera Capensis) at a site in the Eastern Cape, South Africa / The ecology of honey plants in the Eastern CapeMerti, Admassu Addi January 2003 (has links)
From an apicultural point of view the Cape fynbos is under-utilised and our knowledge of its utilization by the Cape honeybees is incomplete. The key aim of this study was to test the hypothesis that the Cape honeybees utilize the fynbos species as the preferred source of nectar and pollen. Subsidiary aims included distinguishing vegetation communities in the area, identifying pollen and nectar sources, the relationship between brood population and seasonal pollen collection patterns, examining the effect of meteorological factors on pollen collection. The study site was on Rivendell Farm within the Eastern Cape Albany district: an area of high species richness. A checklist of vascular plant species was produced revealing 97 families, 271 genera and 448 species. A classification by two-way indicator species (TWINSPAN) recognized seven vegetation communities: Forest, Bush clumps, Acacia savanna, Grassland, Grassy fynbos, Fynbos and Shrubland. Direct field observations of the foraging of Cape honeybees identified 54 nectar and pollen source plant species. Honeybee pollen loads trapped from four colonies of hives identified 37 pollen source plants of which Metalasia muricata, Eucalyptus grandis, Eucalyptus camaldulensis, Erica chamissonis, Helichrysum odoratissimum, Helichrysum anomalum, Crassula cultrata and Acacia longifolia were the predominant pollen source plants. It was also found that 60% of pollen yield derived from fynbos vegetation. The pollen source plants came from both Cape endemic and from nonendemic species. Thus we reject the hypothesis that Cape honeybees selectively forage fynbos species as a preferred source of pollen and nectar. The examination of the effect of temperature, wind-speed and temperature on pollen collection activity of honeybees revealed that: a temperature range of between 14°C to 26°C was optimal for pollen collection; wind speeds of up to 4m/s were conducive for pollen collection; relative humidity was found to have no significant influence on pollen collection. Pollen collection and brood rearing patterns are positively correlated with flowering intensities, but we found in our Eastern Cape study site that brood rearing was not limited to the spring flowering season but did extend to the end of summer. In order to determine the available nectar yield of common plant species hourly secretion of nectar volumes was measured for 24 hours to determine the variation of available nectar during different times of the day. In all nectar producing species the nectar volume was high in the early morning and declined as the day progressed. We found that the volume of available nectar was affected by prevailing temperature and humidity around the flowers.
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A study on an altitudinal gradient investigating the potential effects of climate change on fynbos and the Fynbos-Succulent Karoo boundaryAgenbag, Lize 12 1900 (has links)
Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2006. / Global circulation models predict that the Cape Floristic Region (CFR), a biodiversity hotspot, in
the near future will be subjected to rising temperatures and widespread droughts as a result of
rising atmospheric CO2 causing global climate change. It is predicted that climate change will
lead to a southward shift of the Succulent Karoo, a neighbouring more drought tolerant biome,
and a possible invasion of Fynbos, the main vegetation type of the CFR, by succulent species.
In this research project, the effects of climate change on Fynbos, and the likelihood of Succulent
Karoo invading Fynbos are assessed by means of various monitoring and experimental studies
on an altitudinal gradient spanning a natural transition between fynbos and succulent karoo
vegetation. An analysis of plant species diversity and turnover on the gradient revealed high
species turnover between succulent karoo and the rest of the gradient, associated with a
boundary between two soil types: shale (associated with succulent karoo) and sandstone
(associated with fynbos). Phenological monitoring of fynbos species across the gradient showed
how growth of fynbos species is affected negatively by high temperatures, and that low but
regular rainfall is required to sustain growth during the dry Mediterranean summer.
Retrospective growth analysis of Proteaceae species pairs with contrasting range sizes revealed
that small geographic ranges do not signify low tolerance of climate variation, but rather that
faster growing species are more sensitive to interannual climate variation than slow growing
species. Exposing fynbos species to experimental drought confirmed that faster growing species
will be more severely affected by climate change than slow growing species with conservative
water use strategies. This experiment also confirmed the importance of rainfall reliability for
growth in fynbos species when a naturally occurring prolonged dry period affected some species
more severely than the drought treatment of an average reduction in rainfall. A reciprocal
transplant experiment exposed fynbos seedlings to both warmer and drier conditions when they
were planted outside of their natural ranges in the succulent karoo. Soil type as a barrier to
invasion of fynbos by succulent karoo was also tested. Soil type was found to be not limiting to
succulent karoo species and competition and disturbance was revealed to be more important in
determining the fynbos-succulent karoo boundary than climate. It was concluded that
productivity in fynbos will be adversely affected by rising temperatures and that differing
responses to climate change between slow and fast growing species will lead to shifts in
dominance among species, and consequently altered community structures and vegetation
dynamics. Fires are likely to facilitate invasions of marginal habitats by succulent karoo because
of sensitivity of fynbos regeneration stages to high temperatures and drought.
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Post-fire effects of invasive exotic plants on seed banks, regeneration, soil chemistry and selected soil microbial populations in the Silvermine Nature Reserve, Cape Peninsula, South AfricaCilliers, Charl Daniel 04 1900 (has links)
Thesis (MSc) -- University of Stellenbosch, 2002. / ENGLISH ABSTRACT: The fires, which occurred during January 2000 on the Southern Cape Peninsula, Cape Province, South
Africa, focused attention on the importance of sound, informed management of exotic plant invaders in
fynbos, especially at the urban interface. The fires also highlighted the relative lack of knowledge about
the combined impacts of fire, exotic plants and the exotic-clearing programme on soil seed banks and
regeneration.
This study examines soil borne seed banks, regeneration, soil chemistry and micro biota in different postfire
environments, focusing on three components of exotic plant management: The post-fire effects of
standing invasive exotic plants; stacks of slashed exotic plant material which were deliberately burnt and
stacks reduced to heat scars by a wildfire.
The primary hypothesis addressed is that post-fire vegetation regeneration patterns, seed bank diversity
and seed bank abundance are linked to pre-fire vegetation characteristics and, in particular, to the
treatment of exotic plant species. It is also hypothesised that soil microbe population sizes are linked to
pre-fire vegetation and soil chemical composition.
Differences in soil seed banks, soil micro biota and vegetation regeneration patterns occur in different
post-fire environments. High volumes of (live or dead) woody exotic biomass negatively impact upon postfire
indigenous species diversity and abundance, both above and below-ground. Soil seed banks and
above-ground regeneration decline with increasing fire intensity, wildfire burnt stack treatments showing
the largest declines followed by wildfire burnt standing exotics, control burnt stacks, wildfire burnt cleared
areas and wildfire burnt Mountain Fynbos treatments. Persistent indigenous seed banks are found under
some exotic dominated stands. Heat damage, associated with high woody exotic biomass, affects seeds
of all species into deep soil layers. Depth of burial is a more important determinant of seed survival during
fires than seed size.
Soil microbial populations are variably affected by exotic plants, their management and increases in fire
intensity. The most drastic microbial population changes are in post-fire treatments of high exotic plant
biomass. Soil chemistry affects microbial population sizes as does seasonal climatic changes.
In this thesis vegetation, seed bank and microbial responses to various exotic plant management
practices are shown and management recommendations are made.
Keywords: exotic plants, fire, Fynbos Siome, microbes, post-fire succession, soil seed banks. / AFRIKAANSE OPSOMMING: Die Januarie 2000 vure op die Suid Kaapse Skiereiland het fokus gerig op die belangrikheid van
goeie, ingeligte bestuur van uitheemse indringerplante in fynbos, veral naby stedelike gebiede.
Die vure het ook 'n relatiewe .gebrek aan kennis aangaande die gekombineerde impakte van vuur,
uitheemse plantegroei en indringer plant beheer programme op grond saadbanke en die hergroei
van plante na 'n vuur aan die lig gebring.
Hierdie projek bestudeer die invloed van vuur op grond saadbanke, hergroei van plante, grond
chemie en mikro-organismes. Die klem lê op drie komponente van uitheemse plant bestuur: waar
staande uitheemse plante voorkom; waar skoongekapte uitheemse plante in hope gestapel is en
gekontraleerd gebrand is en waar soortgelyke hope in 'n onbeplande weghol vuur gebrand is.
Die primêre hipotese is dat plant herstelpatrone, saadbank diversiteit en grootte gekoppel is aan
veldtoestande voordat daar gebrand is, en veral aan die bestuur van uitheemse plantspesies. Nog
'n sentrale hipotese is dat die grootte van grond mikrobiale populasies gekoppel is aan veld
toestande voor die brand en aan grond chemiese samestelling.
Hierdie studie dui verskille aan in grond saadbanke, mikro-organismes en plant hergroeipatrone
onder verskeie toestande na vuur. Die brand van hoë volumes (lewende of dooie) houtagtige
uitheemse plant biomassa benadeel inheemse plant spesie diversiteit en getalle (bo en onder die
grond oppervlak). Grond saadbanke neem af met vehogings in vuur intensiteit. Die grootste
afnames is in wegholvuur gebrande gestapelde uitheemse plantmateriaal gevolg deur wegholvuur
gebrande staande uitheemse plante, opsetlik gebrande hope uitheemse plante, gebrande
skoongekapte areas en wegholvuur gebrande Berg Fynbos. Ou inheemse saadbanke is gevind
onder sommige areas wat voor die vuur oorheers was deur uitheemse plantegroei. Hitteskade,
geassosieer met hoë volumes houtagtige uitheemse biomassa, affekteer sade van alle spesies tot
diep in die grond. Saad oorlewing tydens brande is meer geaffekteer deur diepte van begrawing in
die grond as deur saad grootte. Grond mikro-organisme populasies is geaffekteer deur uitheemse indringer plante, die bestuur van
uitheemse plante en vuur intensiteit. Die grootste veranderinge is waar die biomassa van uitheemse
plantegroei baie hoog is. Grond chemiese samestelling en seisoenale veranderinge in
weerspatrone affekteer die grootte van mikrobiale bevolkings.
In hierdie tesis word verskille in plantegroei, saad store en grond mikrobes, soos geaffekteer deur
uitheemse plant beheer programme uitgewys en voorstelle vir toekomstige bestuur gemaak.
Sleutelwoorde: Fynbos Bioom, grond saad stoor, mikrobes, plant hergroei,
uitheemse plante, vuur.
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Attitudes and behaviour of landholders towards the conservation of Overberg Coastal Renosterveld, a threatened vegetation type in the Cape Floral KingdomWinter, Susan Jean 12 1900 (has links)
Thesis (MScConsEcol) -- Stellenbosch University, 2003. / ENGLISH ABSTRACT: This thesis describes the findings of a survey to investigate the attitudes and behaviour of private landholders
towards the conservation of Overberg Coastal Renosterveld, a highly endangered grassy-shrubland of the
Cape Floral Region (CFR) lowlands, now 94% transformed. Personal interviews were conducted with 36
farmers in the Overberg region of the Western Cape, by administering a questionnaire. The following aspects
were quantitatively described using the Statistical Package for Social Scientists (SPSS): Renosterveld
management and utilisation behaviour, perceived value of Overberg Coastal Renosterveld; landholder
knowledge of its conservation importance and willingness to conserve it. Attitudes towards incentives for
conservation; conservancies; and the provincial conservation authorities were also investigated. Willingness
to conserve was explored further using SPSS cross-tabulation analyses. It was found that farmers who were
more willing to conserve were younger, did not necessarily have a better education, and owned larger farms
(> 500 ha) with a greater amount of remnant renosterveld (> 300 ha) than farmers less willing to conserve.
Attitudes towards Overberg Coastal Renosterveld were largely negative, due to certain associated plants and
animals which are problems for farmers, and because it is not economically advantageous to retain it.
However, provision of incentives (of which assistance with fencing and land management was most
attractive) and increased extension support will provide practical positive inducements for conservation.
There is also a need for more landholder education regarding the scarcity of coastal renosterveld to prevent
transformation of remaining fragments. The second component of the study aimed to construct a user-friendly index to measure the conservation
attitudes of landholders towards conserving Overberg Coastal Renosterveld. An interative item analysis was
executed on the data, using Spearman Rank Order correlations and Cronbach's Alpha. Results yielded an
index with two dimensions and a Cronbach Alpha co-efficient of 0.67. The dimensions or components of
conservation attitude towards renosterveld included: (i) a landholders' perception of the perceived benefit of
Overberg Coastal Renosterveld; and (ii) their willingness to conserve it. The mean conservation attitude
score was 0.6 (± 0.03), indicating that landholder attitudes were generally sympathetic towards renosterveld
conservation. This suggests that while many landholders do not place a high value on Overberg Coastal
Renosterveld due to its low agricultural value, their willingness to conserve it is in some cases higher than
expected, which possibly explains the above-average mean conservation attitude score. An analysis of
variance showed that the following variables were significantly, positively correlated with conservation
attitude: (i) area of Overberg Coastal Renosterveld; (ii) landholder environmental group membership status;
(iii) presence of ecotourism activities on the property; and (iv) how long the property had been in the
owner's family. The intended application of the index is that index scores (amenable for use in a
Geographical Information System database) can assist conservation practitioners in deciding where resources should be allocated, on the assumption that high-scoring individuals are more likely to want to take part in
conservation initiatives. / AFRIKAANSE OPSOMMING: Hierdie proefskrif beskryf die bevindings van 'n opname waarin die houdings en gedrag van private
grondeienaars ten opsigte van Overberg Kustelike Renosterveld ondersoek word. Altesaam 94% van die
oorspronklike renosterveld, 'n hoogs bedreigde, grasagtige struikveld in die laaglande van die Kaapse
Planteryk (KPR) , is reeds getransformeer en verander. Persoonlike onderhoude is met 36 boere in die
Overbergstreek van die Wes-Kaap gevoer en 'n vraelys is aan hulle gestel. Die "Statistical Package for
Social Scientists" (SPSS) is gebruik om die volgende aspekte kwantitatief te beskryf: die bestuur en
benutting van Overberg Kustelike Renosterveld; die waarde wat toegeskryf word aan hierdie renosterveld;
asook grondeienaars se kennis oor die bewaringsbelang van Overberg Kustelike Renosterveld en hul
bereidwilligheid om dit te bewaar. Houdings jeens aansporingsmiddele om bewaring te bevorder, bewareas
en die provinsiale bewaringsowerhede is ook ondersoek. Private grondeienaars se bereidwilligheid om
betrokke te raak by bewaringswerk is verder ondersoek deur gebruik te maak van die SPSS-kruistabelleringsanalise.
In vergelyking met boere wat nie bewaring ondersteun nie, is gevind dat die meer
bewaringsgesinde boere jonger is, nie noodwendig 'n beter opvoeding het nie, en groter plase (>500 ha) besit
waarop meer brokkies oorblywende Overberg Kustelike Renosterveld (>300 ha) gevind word. Grondeienaars
se houding jeens Overberg Kustelike Renosterveld was grootliks negatief. Dit is as gevolg van sekere
verwante plante en diere wat deur boere as probleme ervaar word, en omdat dit nie ekonomies lewensvatbaar
is om renosterveld te behou nie. Die beskikbaarheidstelling van aansporingsmiddele (waarvan hulpverlening
met omheinings en grondbestuur die aantreklikste was), en 'n toename in landbou-voorligting is egter
praktiese en positiewe dryfvere wat bewaring kan bevorder. Daar is ook 'n behoefte vir meer opvoeding van
grondeienaars oor aspekte soos die skaarsheid van Overberg Kustelike Renosterveld, sodat die verdere
transformasie van oorblywende fragmente voorkom kan word.
Die tweede gedeelte van die studie was daarop gemik om 'n gebruikersvriendelike indeks te ontwikkel
waarmee die bewaringsgesindheid van grondeienaars teenoor die bewaring van renosterveld gemeet kan
word. Deur gebruik te maak van Spearman se rangorde-korrelasies en Cronbach se Alpha is die data aan 'n
herhalende item-analise onderwerp. Die resultate het 'n indeks met twee dimensies en 'n Cronbach Alpha-koëffisiënt
van 0.67 gelewer. Die dimensies of komponente van bewaringsgesindheid jeens renosterveld het
onder meer ingesluit: i) 'n grondeienaar se opvatting oor die moontlike voordeel van Overberg Kustelike
Renosterveld en ii) sy/haar bereidwilligheid om dit bewaar. Die gemiddelde telling vir bewaringsgesindheid
was 0.6 (± 0.03), wat in die algemeen 'n simpatieke houding jeens die bewaring van Overberg Kustelike Renosterveld onder grondeienaars aandui. Hiervolgens blyk dit dat alhoewel heelwat grondeienaars weens
die lae landbouwaarde van renosterveld nie 'n hoë waarde op hierdie plantegroeitipe plaas nie, hulle
bereidwilligheid om dit te bewaar soms verwagtinge oortref. Dit is dalk 'n moontlike verklaring vir die bogemiddelde
gemiddelde bewaringsgesindheidtelling. 'n Variansie-analise het 'n noemenswaardige, positiewe
korrelasie met bewaringsgesindheid ten opsigte van die volgende veranderlikes getoon: i) area van Overberg
Kustelike Renosterveld; ii) die grondeienaar se moontlike lidmaatskap van 'n bewaringsgroep; iii) die
teenwoordigheid van ekotoerisme-bedrywighede op die eiendom; en iv) die tydperk wat die eiendom al in
besit van die grondeienaar se familie is. Die voorgestelde gebruik van die indeks is toepaslik omdat die
indeks-tellings (wat vir gebruik in 'n Geografiese Inligtingstelsel databasis aangepas kan word) bewaringslui
kan help met besluite random die toekenning van hulpbronne. Die aanname is dat individuele grondeienaars
wie hoë tellings aangeteken het, met alle waarskynlikheid meer geredelik aan bewaringsinisiatiewe sal wil
deelneem.
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Fynbos riparian biogeochemistry and invasive Australian acaciasNaude, Minette 03 1900 (has links)
Thesis (MScConEcol)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Riparian ecotones, transitional areas between upland terrestrial communities and aquatic ecosystems, are very dynamic and complex ecosystems with intrinsic ecological properties differing in spatial structure, function and temporal dynamics. Riparian habitats along rivers of the Mediterranean south-western Cape are sensitive to environmental change and particularly vulnerable to invasion by invasive alien plants (IAPs), especially nitrogen-fixing Acacia spp., and yet relatively little work has focused on how riparian ecosystems in this region respond to such stressors. The important roles that intact riparian vegetation play in maintaining ecosystem integrity and services have been increasingly highlighted as we acknowledge the degradation of these habitats. While the Working for Water (WfW) programme has been shown to be very successful in eradicating IAPs in riparian zones in the short-term, the extent to which riparian ecosystems recover following alien clearing activities remains poorly understood. The results presented in this study addressed several different aspects of riparian structure and function and acts as a steppingstone for guiding future research and management in riparian zones by adding to the evaluation of the success of clearing initiatives and restoration thereof.
The aim of this study was to assess plant functional type (PFT) cover, soil physical and chemical properties, and selected biogeochemical processes in natural, Acacia- invaded and cleared riparian ecotones and associated non-riparian upland fynbos. Fieldwork was performed in mountain and foothill sections of six perennial river systems within the south-western Cape. Eleven sites of three categories were chosen: four natural sites (uninvaded); four moderate to highly invaded sites (predominantly A. mearnsii); and three cleared sites (a formerly invaded site that had been cleared more than 7 years prior to the study). Within each site, four to five replicate plots were established along each of three geomorphological zones (wet bank, dry bank, and upland fynbos). Seasonal soil samples were collected for a period of one year.
Results from this study showed that PFT cover and composition, soil physical and chemical properties and rates of nitrogen (N) and phosphorus (P) mineralization differed amongst invasion status, between geomorphological zones and across seasons. Regarding most soil physical and chemical properties and indices N and P cycling, river floodplains (dry banks) were very similar to terrestrial uplands. Acacia spp. changes soil properties and affects plant functional attributes by i) enriching the system with N; ii) enhancing litter inputs; iii) altering soil physical properties; iv) changing the composition and reducing the cover of PFT; and v) enhancing P mineralization rates. Although measured soil physical and chemical properties and N and P mineralization rates were reduced to levels that were similar to or resembled the situation at natural areas, available inorganic N remained two times higher after more than seven years of clearance. Furthermore, cleared areas were characterized by sparse woody cover and a high cover of alien grasses. Correlations between soil silt and clay content and several soil properties measured in this and other studies indicates important linkages between soil texture and resource availability.
Clearing Acacia spp. may initiate restoration of invaded riparian ecosystems, but changes in ecosystem function (e.g. elevated soil N availability) as a result of invasion may necessitate active restoration following the removal of the alien species. Active restoration under such conditions would be required to facilitate the restoration of cleared riparian communities. However, we still lack the mechanistic understanding around fynbos riparian recovery after clearing, as the success of restoration may depend on complex interaction and feedback cycles between plants and their physical environment. A greater comprehensive understanding of fynbos riparian ecological processes will not only improve the effectiveness of restoration initiatives by integrating science and management, but also advance the field of riparian ecology. / AFRIKAANSE OPSOMMING: Rivier oewerwal-areas, oorgang gebiede tussen aangrensende terrestriële gemeenskappe en akwatiese ekosisteme, is baie dinamiese en komplekse ekosisteme met intrinsieke ekologiese eienskappe wat verskil in struktuur, funksie (bv. biogeochemie siklusse) en temporale dinamika. Oewerhabitatte langs riviere van die Mediterreense suid-wes Kaap is sensitief vir omgewingsveranderinge en kwesbaar vir indringing deur uitheemse plante (bekend as “invasive alien plants” (IAPs)), veral stikstof-fiksering Acacia spp., en relatief min werk het nog gefokus op hoe ekosisteme in die streek reageer op sulke veranderinge in die omgewing. Die belangrike rol wat gesonde oewerwal plantegroei speel in die handhawing van ekosisteemdienste- en integriteit, is al hoe meer uitgelig soos ons die agteruitgang van hierdie habitat in ag neem. Terwyl die Werk vir Water (WvW)-program al dat baie suksesvol was in die uitwissing van IAPs in oewersones in die kort termyn, is die mate waarin oewer-ekostelsels herstel na skoonmaakaksies swak verstaan. Fynbos oewerwal-areas is grootliks ingeneem deur houtagtige IAPs, veral stikstof fiksering Acacia spp. (soos Acacia mearnsii). Die resultate wat in hierdie studie aangebied is, het verskillende aspekte van oewer- struktuur en funksie aangespreek en dien as middel vir toekomstige navorsing en bestuur van oewerwal ekosisteme deur by te dra tot die evaluering van die sukses van skoonmaak inisiatiewe en die herstelproses daarvan.
Die doel van hierdie projek was om die moontlikhede vir herstel van fynbos owerwal-ekostelsels te evalueer deur middel van verskeie grond- fisiese en chemiese eienskappe; plant funksionele groep dekking (genoem ‘plant functional types’ (PFT)); en geselekteerde grond biogeochemie prosesse in natuurlike, Acacia- aangetaste, en skoongemaakte rivierstelsels en nabygeleë terrestriese areas te vergelyk. Veldwerk is gedoen in bergstroom en voetheuwel rivierseksies van ses standhoudende rivierstelsels in Suid-wes Kaap, Suid Afrika. Van uit hierdie geselekteerde rivierstelsels is elf studie areas van drie kategorieë (of indringing status) gekies: vier natuurlike areas (nie aangetas); vier gematig- tot hoogs aangetaste areas (hoofsaaklik A. meanrsii); en drie skoongemaakte areas (rivieroewers wat meer as sewe jaar van te vore skoongemaak is). Binne elke studie area was vier tot vyf soortgelyke persele gevestig by elke van drie breë geomorfologiese sones: naamlik nat-, droë en hoogliggende terrestriese fynbos. Seisoenale grondmonsters vir 'n tydperk van een jaar is geneem.
Resultate van hierdie studie het getoon dat PFT dekking en samestelling, grond fisiese- en chemiese eienskappe en N-mineralisasie en suur fosfatase aktiwiteit verskil tussen indringing status, geomorfologiese sones en oor seisoene. Ten opsigte van meeste grond fisiese en chemiese eienskappe en indekse van stikstof (N) en fosfor (P) siklusse kom die rivier vogregimes (droë oewersones) baie ooreen met die terrestriële gebiede. Aan die anderkant is die natbanksones gekenmerk deur grondeienskappe wat baie verskil van die ander twee geomorfologiese gebiede. Die gegewens ondersteun die hipotese dat indringing deur Acacia spp. verskeie grondeienskappe verander en plante se funksionele kenmerke beïnvloed deur i) die sisteem met voedingstowwe te verryk (veral N); ii) verhoog die toevoeging van plantmateriaal; iii) verander grond fisiese eienskappe; iv) verander die samestelling en verminder die dekking van PFT; v) en verhoog P biogeochemie. Hoewel grond fisiese -en chemiese eienskappe, en indekse van N en P mineralisasie verminder is tot vlakke wat soortgelyk aan natuurlike areas, het beskikbare anorganiese N twee keer hoër gebly by skoongemaakte gebiede. Nietemin, voorheen skoongemaakte gebiede is weer-binnegeval deur eksotiese grasse en die regenerasie of hertelling van inheemse fynbos gemeenskappe is taamlik beperk, veral houtagtige oewer struike en bome. Korrelasies tussen grond slik-en klei-inhoud en verskeie grondeienskappe gemeet in hierdie en ander studies dui op belangrike skakeling tussen die grondtekstuur en voedingstof beskikbaarheid.
Die opruiming van Acacia spp. mag as aansporing dien vir die herstellingsproses van rivieroewerstelsels, maar veranderinge in die funksie van ekosisteme (bv. verhoogte grond N beskikbaarheid), as gevolg van indringing, mag aktiewe herstel noodsaak nadat die indringer spesies verwyder is. Aktiewe herstel onder sulke omstandighede sal verwag word om die herstel van skoongemaak oewer gemeenskappe te fasiliteer. Ons het wel egter nog 'n gebrek aan die meganistiese begrip in verband met die herstel van fynbos oewerwal areas na opruimings-inisiatiewe, sedert die sukses van herstel kan afhang van komplekse interaksie en terugvoer siklusse tussen die plante en hul fisiese omgewing. ʼn Meer omvattende begrip van fynbos rivieroewer ekologiese prosesse sal nie net die doeltreffendheid van opruimings-inisiatiewe deur die integrasie van wetenskaplike navorsing en bestuur verbeter nie, maar ook vooraf die gebied van rivieroewer-ekologie.
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The restoration potential of fynbos riparian seed banks following alien clearingVosse, Shelly 12 1900 (has links)
Thesis (MScConsEcol(Conservation Ecology and Entomology)--University of Stellenbosch, 2007. / Riparian areas are highly complex systems with varying levels of disturbance that are highly susceptible to invasion by alien plants. Once invaded, riparian areas play a major role in the dispersal and spread of invasive alien plants (IAPs) through the river system and, in some cases, to neighbouring landscapes. Riparian areas have therefore been prioritized by many alien clearing initiatives in South Africa. Current practice for the restoration of cleared areas is minimal and relies mainly on the un-aided recovery of native species from residual individuals and soil stored seed banks. Little research, however, has been done on the effectiveness of this approach or the extent to which riparian seed banks contribute towards community restoration. This study is part of a national research initiative (Targets for Ecosystem Repair in Riparian Ecosystems in Fynbos, Grassland and Savanna Biomes) funded by Department of Water Affairs and Forestry, in collaboration with Working for Water, The Centre for Invasion Biology and the Universities of Cape Town, Stellenbosch, Rhodes and Witwatersrand. The initiative undertook to investigate different restoration techniques on various invaded sites for their cost-effectiveness, efficiency, practicality and conservation integrity.
This study has three aims. The first is to determine the composition of seed banks in un-invaded riparian areas within the fynbos biome to be used as a benchmark for future research, restoration grading and other management requirements. The second aim is to determine the composition of seed banks in heavily invaded riparian areas, and thus to assess the impact of invasion on the integrity of the seed banks. The third aim is to evaluate the restoration potential of riparian seed banks following the clearing of invasive alien plants (IAPs).
Study sites were selected within four river systems in the south-western part of the Western Cape Province in South Africa: the Berg, Eerste, Molenaars and Wit Rivers. Plots were selected in both invaded (>75% IAP canopy cover; considered “closed” alien stands) and un-invaded (also termed reference, with <25% IAP canopy cover) sections of the river. Replicate plots were established along varying gradients of elevation (mountain stream and foothill) and moisture regimes (dry, wet and transitional bank zones). Soil samples were collected together with above-ground vegetation surveys and comparisons were made. Results from this study confirm those of previous studies that seed banks offer little reference to current aboveground vegetation, but rather offer insight into past vegetation history as well as future vegetation assemblages.
Worldwide, many of the species that characteristically form seed banks are early successional species. A community study was done for the seed bank based on the species that germinated and were identifiable at termination of the project (6 months after initiation). Three clusters of species could be identified. One group comprised 32 generalist species that occurred in both reference and invaded sections of the rivers. A second group comprised 39 species associated with invaded sites, and a third group of 40 species that was associated with reference sites. A few sub-community groups were found within both the “reference” and “invaded” community groups which were assumed to be habitat specific. Most species were “pioneer” or relatively-short lived, early-successional species which play a vital role in the initial post-disturbance vegetation cover, and facilitate establishment of later successional species.
Seed banks are notoriously variable over space and time, and floristic representation is often biased as a result of differences among species in seed production, dispersal and longevity in the soil. The general consensus is that seeds have an irregular, clustered spatial distribution that is dictated by both biological and environmental factors. Within river systems, the irregular clustering can be exceptionally skewed with the influence of pockets of high sediment deposition along the bank. Environmental factors that were found to significantly skew germination results were the presence of fire, as well as the extent and intensity of invasion (duration and cover). The high level of diversity and abundance in reference Berg River mountain stream seed banks was perceived to be a direct result of a moderate fire frequency (between 8-15 years) and the relatively natural state of the vegetation (i.e. very little invasion). Also, diversity and richness of indigenous species from the Wit and Molenaars Rivers were substantially higher in the invaded samples than the reference samples, probably because both river systems have a long history of invasion and other anthropogenic disturbances which would have an effect on the samples from “reference” sections (i.e. even a 25% presence of IAPs seems adequate enough to alter the composition of the seed bank). Correspondence analyses showed that species had clear affinities towards different levels of “key” riparian environmental variables (fire, invasion and anthropogenic disturbance). Most species were associated with moderate levels of fire frequency, invasion history, and anthropogenic disturbance. Comparisons of seed bank species assemblages between the lateral and longitudinal variables of the rivers offered insights into the habitat requirements of certain fynbos and riparian species. Most significant were the results from bank zone comparisons which showed distinct species groupings along the different moisture bands. As could be expected, riparian species were best represented within the wet bank zones and fynbos species within the dry bank zone, while species characteristic of both zones occurred in the transitional zone, making this seed bank zone the richest in species. Mountain stream sections were richer and more diverse than foothill sections over both invaded and reference samples. This is hypothesised to be linked to lower levels of anthropogenic disturbance experienced in the mountain stream sections.
The impact of invasion on the riparian seed bank was most clearly shown through the correspondence analyses for the 20 most frequently occurring species. The seed bank assembly patterns were clearly defined by the state of the river (reference or invaded). Interestingly, this pattern was evident at all three spatial scales; landscape (rivers), reach (mountain stream and foothill sections) and habitat (dry, wet and transitional zones). The reference seed bank assemblage was more tightly grouped, implying that the species were more closely associated with each other and less variable than those of the invaded seed bank assemblages. The species groupings within the invaded seed banks were influenced by variables such as reach and zone, whereas the reference seed bank assemblages seem relatively unaffected by these variables. This implies that the presence of invasive alien plants creates additional variation within the seed bank which alters the natural groupings. At a broad scale, the invaded seed banks were less species rich. This means that not only will the resulting seedling community be harder to predict, but it will also have fewer species. However although generally lower in species richness, the seed banks from almost all invaded rivers interestingly showed a higher diversity of indigenous species than their reference counterparts. This is very promising in terms of rehabilitation of post-cleared riparian sites, but more information is needed to understand the seed bank composition and determine how sustainable the seed banks are for rehabilitation in the long-term. All invaded sections had fewer herbaceous perennial species but more herbaceous annual species. Graminoids made up 50% or more of the seed bank regardless of state (reference or invaded), while woody species (shrubs/shrublets) were generally more prevalent in the reference samples. These results imply that following the removal of invasive alien plants, the vegetation to regenerate from the seed bank is likely to comprise of short-lived, herbaceous species that are not necessarily an accurate reflection of the indigenous riparian community. It is however important to note that this study investigated only the species that were able to germinate over the study period (6 month germination period). Many riparian species may not have been represented because they are either late germinators or may not be present in the soil seed bank at all. In order to gain a holistic understanding of riparian community recruitment, it is recommended that seed bank studies such as this one be included in a more broad scale, long term investigation which takes into account various reproductive strategies used by riparian species.
Research of this nature is in its infancy worldwide and there are many challenges involved in measuring diversity and change in these systems. However, within the scope of this study, I suggest that these results shed light on previously unanswered and important questions regarding the ecology of seed banks in the riparian ecosystems of the Western Cape.
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Significance of direct and indirect pollination ecosystem services to the apple industry in the Western Cape of South AfricaMouton, Madele 03 1900 (has links)
Thesis (MScConEcol (Conservation Ecology and Entomology))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Insect pollinators play an important role in producing crops in global agriculture. Pollinatordependent
crops contribute to maintaining a healthy variety in the human diet and often have a
high market value, beneficial for local or regional economies. Insect crop pollinators can either
be from natural areas adjacent to orchards, or they can be brought into orchards by beekeepers
that manage them. Pollination by wild pollinators is an ecosystem service, while managed
pollinators (mostly honeybees) is a humanly managed service, considered not to be related to the
ecosystem. Ecosystem services and their economic value have often been used as an incentive
for conservation, although it is sometimes difficult to characterise and quantify them. Wild and
managed pollinators have been reported to be threatened in several regions around the world, and
there is concern about the effect a pollination deficit may have on crop production. Different
crops and cultivars have different levels of dependence on insect pollination due to a
combination of biological, physical and management factors. In this study, the pollination
dependence of the Granny Smith apple cultivar and the respective contributions of wild and
managed pollinators are investigated in the Western Cape province of South Africa. Granny
Smith apples show a significant increase in production with insect pollination (wild and
managed). Managed honeybees are more abundant in orchards than wild honeybees, and also
provide a better pollination service. This difference between the pollination service of wild and
managed honeybees are specifically noted in the quality, where managed honeybees pollination
result in significantly more seeds per fruit and consequently produce a better shaped apple. The
study goes further by quantifying the ecosystem services to the managed honeybee industry
through a questionnaire completed by beekeepers. It was found that 49% of the managed hives in
the Western Cape rely to some extent on natural vegetation as a forage source. Furthermore 18%
of honey produced is also from natural vegetation and the wild honeybee population replenish
managed honeybee stocks if they become depleted. Although managed honeybees are not
usually considered an ecosystem service, it is clear that they are still linked to the ecosystem via
these pathways. It is thus obvious that all pollination sources are linked to the environment, not
just wild pollinators. A further economic valuation of the ecosystem service studied, and to the
argument for conservation of pollinators and the resources they depend on. / AFRIKAANSE OPSOMMING: Insek bestuiwing speel ‘n belangrike rol in die produksie van gewasse in landbou wêreldwyd.
Gewasse wat bestuiwing-afhanklik is, dra by tot ‘n gesonde verskeidenheid in die mens se dieët
en hul hoë mark waarde is voordelig vir plaaslike en streeks ekonomieë. Insek bestuiwers kan of
van natuurlike areas langs boorde afkomstig wees, of bestuurde bestuiwers kan deur byeboere in
boorde ingebring word. Bestuiwing deur wilde bestuiwers is ‘n ekosisteem diens, maar die
byeboere verskaf ‘n bestuurde diens, wat nie altyd gereken word om aan die ekosisteem verwant
te wees nie. Ekosisteem dienste en hul ekonomiese waarde word gereeld gebruik as insentief vir
bewaring, alhoewel dit soms moeilik is om dit te karaktariseer en te kwantifiseer. In sekere
streke wêreldwyd is dit bewys dat wilde, asook bestuurde bestuiwers, bedreig is en daar heers
bekommernis dat ‘n tekort aan bestuiwers gewas produksie negatief sal beïnvloed. Verskillende
gewasse en kultivars het verskillende vlakke van bestuiwing-afhanklikheid as gevolg van
verskillende biologiese en fisiese faktore en bestuurspraktyke. In hierdie studie is die
bestuiwings-afhanklikheid van die Granny Smith appel kultivar ondersoek, asook die bydrae van
wilde en bestuurde heuningbye in die Wes-Kaap provinsie van Suid Afrika. Granny Smith appels
toon ‘n betekenisvolle produksie verbetering met insek bestuiwing (wilde en bestuurde bye).
Daar is ‘n groter hoeveelheid bestuurde bye in ‘n boord as wilde bye, en hulle verskaf ook dus ‘n
beter bestuiwingsdiens. Die voordeel van bestuurde bye bo wilde bye word veral in vrug
kwaliteit opgemerk. As bestuurde bye gebruik word, is daar betekenisvol meer sade per vrug en
gevolglik het die appels ook ‘n beter vorm. Verder fokus die studie ook op die kwantifisering
van ekosisteem dienste wat aan die bestuurde heuningby industrie verskaf word, deur inligting
van byeboere te gebruik. Daar is bevind dat 49% van die kolonies bestuurde bye in die Wes-
Kaap is tot ‘n mate afhanklik van natuurlike plantegroei vir voedsel. Verder is 18% van die
geproduseerde heuning ook afkomstig van natuurlike plantegroei se nektar en byeboere vang
wilde kolonies om uitgestorwe bestuurde kolonies te vervang. Dit is dus duidelik dat alle
bestuiwings bronne gekoppel is aan die omgewing, nie slegs wilde bestuiwers nie. ‘n Verdere
ekonomiese waardasie van die onderskeie ekosisteem dienste wat bestudeer is, voeg motivering
by tot die bewaring van bestuiwers en die hulpbronne waarvan hulle afhanklik is.
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The restoration of an alien-invaded riparian zone in grassy fynbos, South AfricaFourie, Saskia January 2013 (has links)
The most recent surveys in South Africa estimate that invasions are still increasing, despite substantial clearing efforts. Riparian systems in South Africa are particularly vulnerable to invasion by woody IAPs. This thesis addresses the restoration of alien‐invaded riparian systems, by investigating the factors that facilitate or constrain spontaneous recovery and influence the trajectories of succession. These factors include invasion history and management history, especially the use of fire. A seedling emergence approach was used to test the presence of a viable pre‐fire seedbank, and the effect of fire on the seed bank. The efficacy of some active restoration interventions was also tested, with the aim to return invasion‐resistant, indigenous vegetation with a structure and function representative of uninvaded sites. The findings of this study indicated the presence of a viable and persistent riparian soil seed bank, even after 30 years of intermtittent invasion as well as two fire cycles under invasion. It shows that the management practice of fell‐and‐burn resulted in high soil temperatures, and that this reduced the indigenous soil seed bank density, especially in the upper soil layer. Clear germination sequences and patterns of emergence over time for different species were observed during this study, with many species exhibiting delayed emergence relative to the timing of the fire event. It is proposed that manipulation of the season of fire could be used to selectively optimise the order of arrival and therefore superior recruitment of some species over others in the Eastern Cape fynbos, and thus alter the trajectories of recovery of vegetation towards a more desired state. Active restoration in the form of indigenous seed and plant additions resulted in a significantly higher indigenous cover after seven months, compared to a control (passive restoration) or restoring with grass. Indigenous cover and composition was also strongly influenced by lateral zonation, and some key guilds and species were missing or present in much lower densities compared to reference sites. Grass restoration significantly suppressed the regeneration of A. longifolia, as well as the regeneration of indigenous species. Biotic resistance can thus be achieved through restoration, and it could be a powerful tool in the management of IAPs, although the deliberate introduction of grass after clearing in fynbos also reduces biodiversity and could have unforeseen consequences to riparian function.
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Nematode soil community structure and function as a bio-indicator of soil health in fynbos and deciduous fruit orchardsKapp, Caro 03 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Soil is a fundamental, non-renewable resource in any ecosystem. To uphold food production for increasing global human populations, it is imperative to develop ways in which to sustain healthy biological productivity and sustainability of agricultural soils. Nematodes are one of the most abundant groups of Metazoa occurring in all soils, and form an integral part of the soil food web at several trophic levels. They respond rapidly to changes within their environments, and can easily be extracted from soil, identified and characterised into functional guilds. Nematodes thus have the potential to impart insight into the condition of the soil food web.
This study aims to establish whether nematodes will be suitable bio-indicators of soil health for the deciduous fruit industry in the Western Cape. Three different objectives have been set to determine the practical use of nematode community structures as a tool for the measurement of soil health. The objectives include describing the nematode community structure, biodiversity and functionality within Fynbos soils; the characterization of organic and conventional orchards; and the differences in nematode soil communities in differently managed soils in an apple orchard. The number of nematodes in each soil sample was quantified and identified to family level. The nematode biodiversity and functionality for each site was determined by evaluating the nematode food webs for trophic group distribution, as enumerated by the Maturity Index (MI), the Enrichment Index (EI), the Structure Index (SI), the Basal Index (BI) and the Channel Index (CI), based on the weighted abundance of coloniser-persister guilds.
The functional guild analysis of Fynbos samples indicated that the enrichment and the structure of any given sample were not bound to a certain area, but it was representative of each of the four quadrats within the faunal analysis. Different geographic areas were found to differ in nematode diversity and functionality, which was mainly associated with dominant plant families and species (such as strong associations between Fynbos families Fabaceae, Solanaceae and Celestraceae with the nematode family Pratylenchidae). The most abundant nematode families present in the Fynbos were Tylenchidae, which are plant-feeding nematodes, and Cephalobidae which are bacterial-feeding nematodes. Despite Tylenchidae and Cephalobidae both having coloniser-persister values (cp-values) of two, they are split up into different feeding types. Cp-2 nematodes are tolerant to disturbances, and occur in all environments. Only one omnivorous family, the Dorylaimida, was identified in Fynbos samples. The average MI value for Fynbos was found to be very low, with a mean value of 1.26. The value obtained indicated the presence of taxa with tolerance to disturbance, which, in turn, indicated the presence of a disturbed soil, in general. The number of plant-parasitic nematodes within the Fynbos soils was low, which was supported by the low plant-parasitic index (PPI) of 0.85. The diversity, richness and evenness values were low, indicating low nematode diversity, but a distribution of abundances amongst the families. The average Hill’s N0 index value was 8.0, indicating that, in general, eight nematode families would have been present in a Fynbos soil sample.
A study was done to determine the biodiversity and the functionality of the nematodes associated with deciduous fruit orchards that were conventionally, or organically, managed. Herbivores were dominant in all the orchards. The organic apple orchard had the lowest numbers of herbivores and fungivores, with the highest number of carnivores. When comparing organic and conventional apricot orchards, higher numbers of plant-parasitic nematodes were found in the organic orchard. Criconematidae occurred in higher numbers in conventional apricot orchard soil. When comparing organic apricots and apples, higher numbers of Criconematidae occurred within the organic apple soil. Overall, higher levels of plant-parasitic nematodes occurred in the organic apricot orchard. The MI indicated that all orchard soils had values below 1.5, indicating disturbance. Conventionally managed apricot orchard soil had the highest MI value of 1.48. The PPI value was highest in organically managed apricot orchards. All orchard soils were located within Quadrat B of the faunal analysis, indicating enrichment and structure. Regarding the diversity, richness and evenness of the distribution, conventional apricot soil had the highest species richness, while organic apple soil had the most even family distribution. Different management practices did not show marked differences in community composition and structure. The species richness of Fynbos soils was comparable to those of deciduous fruit orchards.
Soil samples from eight different soil surface treatments were collected from an apple orchard in the Grabouw area. Treatments were combined according to the soil surface treatments received (chemical control of cover crops and weeds, mulch and mulch + effective micro-organism spray). Bacterivores were dominant in all soil treatments, with the least number being present in the chemical control (of cover crops and weeds) treatment. Sites which received chemical control of cover crops and weeds had higher levels of fungivores, compared to the levels at the other sites. High numbers of Rhabditidae occurred within mulch and mulch + effective micro-organism (EM) treatment sites, while high numbers of Aphelenchidae occurred in chemical control sites. The carnivorous family Ironidae only occurred in mulch + EM sites. Strong associations were found between soil surface applications and nematode families present within the soil. Chemical control (of cover crops and weeds) applications had the highest MI value, while values were equal for the other soil applications. The faunal analysis indicated that the mulch and the chemical control fell within Quadrat A, indicating enriched, but unstructured, soil, while the mulch + EM treatment fell within Quadrat B, indicating enrichment and structure, as well as good overall soil conditions. All the systems were dominated by bacterial decomposition pathways. Controversially, sites that received chemical control of the cover crops and weeds had the highest species richness of all three applications, as well as the highest level of diversity, according to the Simpson Index. As only the cover crops and the weeds were chemically controlled, the soil can be regarded as undisturbed, which explains the results obtained in this study. Clear differences in nematode community structure and composition were observed between the different soil applications in the apple orchard. / AFRIKAANSE OPSOMMING: Grond is 'n fundamentele, nie-hernubare hulpbron binne enige ekosisteem. Ten einde voedselproduksie vir die toenemende globale menslike bevolking te handhaaf, is dit noodsaaklik om maniere te ontwikkel om gesonde biologiese produktiwiteit en volhoubaarheid van landbougrond in stand te hou. Nematodes is een van die volopste Metazoa in alle gronde en vorm 'n integrale deel van die grond voedsel-web op verskeie trofiese vlakke. Hulle reageer vinnig op veranderinge binne hul omgewings, kan maklik ekstraheer en identifiseer word; en ook maklik in funksionele gildes ingedeel word. Nematodes het ook die potensiaal om insig oor te dra ten opsigte van die toestand van die grond voedsel-web.
Hierdie studie het ten doel om vas te stel of nematodes geskikte bio-indikatore van grond gesondheid kan wees spesifiek vir die sagtevrugte bedryf in die Wes-Kaap. Drie verskillende doelwitte is gestel om die praktiese gebruik van nematode populasie samestelling as 'n instrument vir die meting van grond gesondheid te gebruik. Die doelwitte sluit in die nematode populasie samestelling, biodiversiteit en funksionaliteit binne natuurlike Fynbos; organies verboude versus konvensionele boorde; en die verskil in nematode populasie samestelling tussen verskillend behandelde en bestuurde grondpersele binne ʼn appel boord. Die nematode biodiversiteit en funksionaliteit vir elke perseel was bepaal deur die evaluering van die nematode voedselweb vir trofiese groep verspreiding en enumerering deur die Maturity Index (MI) en die Enrichment Index (EI), Strukturele Indeks (SI), Basale Indeks (BI) en Channel Index (CI) wat gebaseer is op die geweegde oorvloed van koloniseerder-persister gildes.
Die funksionele gilde vir Fynbos monsters het aangedui dat die verryking en struktuur van enige gegewe perseel nie gebonde is aan ʼn bepaalde gebied nie, aangesien dit verteenwoordig was in elk van die vier kwadrante van die Fauna Analiseerder. Daar is gevind dat verskillende areas verskil in nematode diversiteit en funksionaliteit, wat hoofsaaklik geassosieer was met die dominante plant families en spesies in die omgewing. Die volopste nematode familie wat teenwoordig was in die Fynbos was Tylenchidae, wat plant-voedende nematodes is, en Cephalobidae, wat bakterie-voedend is. Tylenchidae en Cephalobidae het beide ʼn cp-waarde van twee, maar is verdeel in verskillende
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tipes voedingsgroepe. Die cp-2 nematodes is verdraagsaam vir versteurings en kom in alle omgewings voor. Slegs een omnivoor familie is geïdentifiseer in Fynbos monsters, nl. die Dorylaimidae. Die gemiddelde MI waarde vir Fynbos was laag, met 'n gemiddelde waarde van 1.26. Hierdie waarde is ʼn aanduiding van die teenwoordigheid van taxa met verdraagsaamheid tot versteuring, wat op sy beurt 'n versteurde grond in die algemeen aangedui het. Die aantal plant-parasitiese nematodes binne die Fynbos-gronde was laag, wat ondersteun word deur die lae PPI-waarde van 0.85. Die waardes vir die diversiteit, spesie-rykheid en egaligheid was laag, wat dui op 'n lae nematode diversiteit, maar 'n egalige verspreidings onder families. Die Hill’s N0 indeks waarde was gelyk aan 'n gemiddelde van 8.0 en dui daarop dat in die algemeen agt nematode families teenwoordig sal wees in 'n Fynbos grondmonster.
'n Studie is gedoen om die biodiversiteit en funksionaliteit van nematodes wat verband hou met vrugteboorde wat organies en konvensioneel bestuur is te bepaal. Herbivore was dominant in alle boorde. Organiese appels het die laagste aantal herbivore en fungivore gehad en die hoogste aantal karnivore. Wanneer organiese en konvensionele appelkoosboorde met mekaar vergelyk is, was hoër getalle van plant-parasitiese nematodes gevind in die organiese boord. Criconematidae was teen ʼn groter aantal in die grond van die konvensionele appelkoosboord gevind. Met die vergelyking van organiese appelkose en appels word, is ʼn hoër aantal Criconematidae binne die organiese appelgrond aangetref. In die algemeen was hoër vlakke van plant-parasitiese nematodes gevind in die organiese appelkoosboord. Die MI het getoon dat alle boord waardes laer as 1.5 gehad het, wat daarop dui dat die gronde versteurd is. Die konvensioneel bestuurde appelkoosboord het die hoogste MI waarde gehad met ʼn vlak van 1.48. Die waarde vir die PPI was die hoogste in organies bestuurde appelkoosboorde. Alle boord gronde is geleë binne kwadrant B van die Fauna Analiseerder, wat dui op verryking met struktuur. Met betrekking tot die diversiteit, spesie-rykheid en egaligheid van die verspreiding van families, het konvensionele appelkoos grond die hoogste spesierykheid, terwyl die gronde van die organiese appelboord die mees egalige familie verspreiding vertoon het. Verskillende bestuurspraktyke nie toon nie merkbare verskille in die gemeenskap samestelling en struktuur nie. Die spesie-rykheid van Fynbos gronde is vergelykbaar met dié van sagtevrugte-boorde.
Monsters is geneem van agt verskillende grondeoppervlak-behandelings in ‘n appelboord in die Grabouw area. Die behandelings is gekombineer volgens die grond toediening wat dit ontvang het (chemiese beheer van dekgewasse en onkruid, deklaag en ‘n deklaag + effektiewe mikro-
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organismes). Bakterievoedende nematodes was dominant in elke grondoppervlak-behandeling, met die minste teenwoordig in die behandelings wat chemiese beheer van die dekgewasse en onkruid ontvang het. Behandelings wat chemiese beheer van die dekgewasse en onkruid ontvang het, het ook hoër vlakke van fungivore in vergelyking met die ander behandelings. ʼn Hoë aantal Rhabditidae het voorgekom in grondmonsters van die deklaag en die deklaag + EM (effektiewe mikro-organismes) behandeling persele, terwyl ʼn groot aantal Aphelenchidae voorgekom het in chemiese beheer persele. Die predatoriese familie, Ironidae, het slegs voorgekom in persele wat die deklaag + EM behandeling ontvang het. Sterk assosiasies bestaan tussen grond behandeling en nematode families wat in die grond teenwoordig was. Die chemiese beheer behandeling het die hoogste MI waarde getoon, terwyl waardes vir die ander behandelings laer en gelyk was. Die fauna analise het daarop gedui dat die deklaag en chemiese beheer binne kwadrant A is en dus verryk, maar ook ongestruktureerd is. Die deklaag + EM behandeling het binne kwadrant B geval wat aandui op toestande van verryking en struktuur wat 'n goeie algehele grondtoestand tot gevolg gehad het. Al die stelsels is oorbruggingsweë wat oorheers was deur bakteriële ontbinding. Kontroversieel, het persele wat chemiese beheer van die dekgewasse en onkruid ontvang het, die hoogste spesierykheid van al drie behandelings getoon asook die hoogste vlak van diversiteit volgens die Simpson-indeks. Slegs die dekgewasse en onkruid is chemies behandel, nie die grond nie, en dus kan die grond as onversteurd beskou word en die resultate wat verkry is in die studie verklaar. Duidelike verskille in die nematode gemeenskap struktuur en samestelling is waargeneem tussen die verskillende grond behandelings in appel boorde.
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