Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The present global biodiversity crisis is characterized mostly by loss of species due to habitat
destruction but there other major threats – notably invasive alien species. The term “biodiversity hotspot”
has been coined to emphasize areas for conservation prioritization – areas that have high biodiversity under
threat from habitat destruction, invasive species, etc. The Cape Floristic Region (CFR) in the Western Cape
(WC) Province of South Africa has the highest biodiversity of all Mediterranean-type climate regions
globally and is classified among global biodiversity hotspots. The CFR, a Mediterranean-type climate
heathland with a naturally high fire frequency, faces threat from transformation by development, disturbed
(increased) fire frequencies and intensities, and invasive organisms, most notably invasive trees. Such
threats disturb keystone species and keystone processes including insect pollinator assemblages and
associated insect flower visitation webs and frequencies.
Invasive pines are a serious threat to insect flower visitation as pine trees (Pinus spp.) shade out
much indigenous vegetation in the CFR. Little is known of their long-term effects on insect flower visitors
and vegetation recovery in post-pine restoration and recovery areas after such trees are removed. I
investigated the recovery of vegetation and the most important insect pollinator, bees, after the removal of
pines by fire and passive recovery in a CFR valley in the Western Cape.
In 1999, a wildfire burned much of the WC Limietberg Nature Reserve along with an adjacent pine
tree forestry stand - which was then left to recover, providing an ideal opportunity to investigate the enduring
effects of pine afforestation in the CFR. In two data chapters, I compared the post-fire passive recovery of
vegetation (Chapter 2) and bee diversity (Chapter 4) in areas which had previously been planted with pines
vs. those which had contained natural fynbos. To improve on sampling methodology, I conducted an
experiment that demonstrated the Observer Effect in bee sampling with a sweep net (Chapter 3), and I
developed a novel sampling device (Chapter 5) for insect flower visitors.
Sampling of vegetation and bee diversity was conducted in a paired sampling design, where fynbos
(Natural) sub-sites were paired with sub-sites which had previously been afforested with pines (Post-Pine
Recovery; PPR) and the two sub-sites were separated by a distinct, linear boundary (Natural/PPR boundary).
Sampling was conducted along transects parallel to the boundary and extending in both directions from the
boundary into the Natural and in the opposite direction into PPR sub-sites. Five transects were positioned at
3, 10, 20, 30, and 40 m from the boundary (Ecotone) and three were positioned at 60, 80, and 100 m from the
boundary (Deep).
In Chapter 2, I found that natural sub-sites consistently had higher total plant species abundance and
species richness than PPR sub-sites. Approximately two thirds of plant species were more abundant in
Natural sub-sites than in PPR sub-sites. There was no significant correlation in species richness or
abundance with distance from the Natural/PPR boundary. Some genera are cautiously indicated as having lower success in recovery after pine afforestation: Erica spp., Restio spp., Hypodiscus spp. while
Helichrysum spp. is also tentatively indicated to recover well in PPR sub-sites. Soil disturbance and
concomitant disruption of normal ecosystem functions, including pollination, is indicated as a probable
reason for disruption of plant recovery.
In Chapter 3, sweep netting methodology was tested for the Observer Effect. A noticeable increase
in bee visitation frequency to a common generalist plant species in bloom, Metalasia densa, was correlated
with longer waiting periods after I stopped moving indicating the presence of an Observer Effect. This
suggests that sweep netting for bees should only be commenced after a waiting period of five minutes during
which the sweep netter is motionless.
In Chapter 4, using a flight-intercept modified pan trap, I compared bee species richness and bee
species abundance across different seasons and in both mass-flowering and sparser flower patches. There
was no significant difference in bee species richness between Natural and PPR sub-sites. All bee species,
except one complex, were more abundant in Natural sub-sites. Nearly two thirds of all bee species (n=37 of
56) caught with sweep netting and the modified pan trap are undescribed species. Similar to the vegetation,
the effects of soil disturbance as a result of decades of pine forest shading and pine forest litterfall followed
by an unusually hot pine forest fire are indicated as the most likely reasons for lower bee abundance in PPR
sub-sites. This is due to the difficulty associated with viable nest establishment and suitable pollen and
nectar forage availability in disturbed areas.
In Chapter 5, the newly developed Pan and Flight Intercept Combination (PAFIC) trap’s design,
pilot testing, and comparison with the traditional pan trap is discussed. A preliminary test suggests that the
PAFIC trap is more efficient (with higher abundance) than the traditional pan trap.
In Chapter 6, I discuss the implications of the disturbance of pine forestry and unusual pine fire to
plant species and bee species assemblages. Bee-pollination webs in PPR sub-sites are indicated as being
substantially simpler than those in Natural areas as well as compositionally different. The recovery of
pollination as a keystone process in post pine-afforestation areas faces a substantial challenge given the
disturbance to soil that decades of pine afforestation followed by pine forest fire can cause. Some
suggestions are made for the restoration of fynbos areas recovering from pine afforestation including a
discussion of augmenting re-vegetation measures (fynbos seed dispersal and seedling planting) with methods
of restoring of healthy pedogenesis, epigaeic arthropod communities, and fynbos seedbanks. / AFRIKAANSE OPSOMMING: Die huidige globale biodiversiteit krisis is gekenmerk meestal deur die verlies van spesies as gevolg
van die vernietiging van habitat. Maar daar is ook ander groot bedreigings – veral merkbaar indringerspesies.
Die term “biodiversiteit brandpunt” is geskep om gebiede vir bewaring prioritisering te beklemtoon - gebiede
wat 'n hoë biodiversiteit bevat wat bedreig word deur die vernietiging van habitat, indringerspesies, ens. Die
Kaap Floristiese Streek (KFS) in die Wes-Kaap (WK) Provinsie van Suid-Afrika het die hoogste
biodiversiteit van alle Mediterreense tipe klimaat streke wêreldwyd, en is onder die globale biodiversiteit
brandpunte geklassifiseer. Die KFS, 'n Mediterreense-tipe klimaat heideveld met 'n natuurlike hoë brand
frekwensie, word bedreig as gevolg van transformasie deur ontwikkeling, versteurde (verhoogde) vuur
regimes, en indringer organismes, veral indringerbome. Sulke bedreigings versteur hoeksteen spesies en die
hoeksteen prosesse, insluitende insek bestuiwer samestelling en verwante insek blom besoekings webbe en
frekwensies.
Indringer dennebome (Pinus spp.) is 'n ernstige bedreiging vir insek blom besoeking want
dennebome verskaf skaduwee aan baie inheemse plantegroei in die KFS. Min is bekend oor die langtermyn
effekte op insek blom besoekers en plantegroei restorasie na denneboom verwydering en restorasie gebiede
na sodanige bome verwyder word. Ek ondersoek die restorasie van plantegroei en die belangrikste insek
bestuiwer, bye, na die vernietiging van dennebome deur vuur en passiewe herstel in 'n KFS vallei in die
Wes-Kaap.
In 1999 het'n veldbrand baie van die WK Limietberg Natuurreservaat saam met 'n aangrensende
denneboom bosbouplantasie gebrand - wat toe gelaat is om te herstel via intermediêre suksessie na inheemse
fynbos plantegroei. Dit bied 'n ideale geleentheid om die blywende gevolge van denneboom aanplanting in
die KFS te ondersoek. In twee data hoofstukke, vergelyk ek die passiewe herstel van plantegroei na ‘n brand
(Hoofstuk 2) en by diversiteit (Hoofstuk 4) in gebiede wat voorheen geplant is met dennebome teenoor
diegene wat natuurlike fynbos vervat het. Om te verbeter op steekproefmetodiek, het ek 'n eksperiment
onderneem wat demonstreer hoe die Waarnemer Effek by monsterneming met 'n vee-net beïnvloed
(Hoofstuk 3), en het ek 'n nuwe monsterneming toestel ontwerp (Hoofstuk 5) vir insek blom besoekers.
Monsterneming van plantegroei en by diversiteit is uitgevoer in 'n gegroepeerde steekproef ontwerp,
waar fynbos (Natuurlik) sub-terreine gegroepeer is met sub-terreine wat voorheen aangeplant was met
dennebome (Na Denneboom Verwydering Herstel; NDVH) en die twee sub-terreine is geskei deur 'n
duidelike, lineêre grens (Natuurlik / NDVH grens). Steekproefneming is gedoen langs transekte parallel tot
die grens en versprei in albei rigtings van die grens tot binne die natuurlike fynbos en in die teenoorgestelde
rigting tot binne NDVH sub-terreine. Vyf transekte is geposisioneer binne 50 m van die grens (Oorgang
sone) en drie is ver geplaas van die grens (Diep).
In Hoofstuk 2 het ek gevind dat natuurlike sub-terreine konsekwent hoër totale getal plant individue en spesierykheid as NDVH sub-terreine gehad het. Ongeveer twee derdes van plantspesies was meer volop
in natuurlike sub-terreine as in NDVH sub-terreine. Daar was geen beduidende korrelasie in spesierykheid
of totale hoeveelheid plant individue met betrekking tot afstand van die Natuurlike /NDVH grens. Sommige
genera word versigtig aangedui as met laer sukses in die restorasie terreine na denneboom aanplanting: Erica
spp., Restio spp., Hypodiscus spp. terwyl Helichrysum spp. voorlopig aangedui is as goed herstel in NDVH
sub-terreine. Grondversteuring en gepaardgaande ontwrigting van normale funksionering van die
ekosisteem, insluitend bestuiwing, word aangedui as 'n waarskynlike rede vir die ontwrigting van die herstel
van plantegroei.
In Hoofstuk 3 is vee-net metodologie getoets vir die Waarnemer Effek. 'N merkbare toename in by
besoeking frekwensie van 'n algemene plantspesie in blomtyd, Metalasia densa, is gekorreleer met langer
wagtydperke nadat ek gestop het om te beweeg, en dui dus op die teenwoordigheid van 'n Waarnemer Effek.
Dit dui daarop dat die vee-net vir bye eers gebruik moet word na 'n wagtydperk waartydens die waarnemer
bewegingloos verkeer.
In Hoofstuk 4, met behulp van 'n vlug-onderskep gewysigde pan lokval, het ek by spesierykheid en
totale by hoeveelheid vergelyk oor verskillende seisoene en in beide massa-beblomde en yler blom kolle.
Daar was geen beduidende verskil in by spesierykheid tussen natuurlike en NDVH sub-terreine. Alle by
spesies, behalwe een spesie kompleks, was meer volop in natuurlike sub-terreine. Byna twee derdes van alle
by spesies (n = 37 van 56) gevang met vee-nette en die van die gewysigde pan lokvalle is onbeskryfde
spesies. Soortgelyk aan die plantegroei, is die gevolge van grondversteuring as gevolg van dekades van
denneboom bos skadu en denneboom bos blaar afval gevolg deur 'n buitengewoon warm denneboom bos
brand as die mees waarskynlike redes vir laer by hoeveelheid in NDVH sub-terreine aangedui. Dit is as
gevolg van die probleme wat verband hou met lewensvatbare nes vestiging en geskikte stuifmeel en nektar
voer beskikbaarheid in versteurde gebiede.
In Hoofstuk 5 is die nuut ontwikkelde Pan en Vlug Onderskep Kombinasie (PEVOK) lokval
ontwerp, aanvanklike toetsing, en vergelyking met die tradisionele pan lokval bespreek. 'N Voorlopige toets
dui daarop dat die PEVOK lokval meer doeltreffend (met 'n hoër oorvloed) is as die tradisionele pan lokval.
In Hoofstuk 6 bespreek ek die implikasies van die versteuring van denneboom bosbou en ongewone
denneboom vuur met betrekking tot plant spesies en by spesies samestelling. By-bestuiwing webbe in
NDVH sub-terreine word aangedui as wesenlik eenvoudiger as dié in natuurlike areas asook verskillend in
samestelling. Die herstel van bestuiwing as 'n hoeksteen in na denneboom-aangeplante gebiede staar 'n
aansienlike uitdaging in die gesig, gegee die versteuring van grond wat dekades van denneboom aanplanting
gevolg deur denneboom bos brand kan veroorsaak. Sommige voorstelle is gemaak vir die herstel van fynbos
gebiede wat herstel van denneboom aanplanting, insluitend 'n bespreking van die aanvulling van plantegroei
hervestiging maatreëls (fynbos saadverspreiding en saailinge plant) met die metodes van die herstel van 'n
gesonde pedogenese, bogrondse geleedpotige gemeenskappe, en fynbos saadbanke.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/97796 |
| Date | 12 1900 |
| Creators | Gardee, Muhammed Nizaar |
| Contributors | Samways, M. J., Bazelet, C. S., Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | xvi, 141 pages : illustrations |
| Rights | Stellenbosch University |
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