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.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/53006 |
| Date | 04 1900 |
| Creators | Cilliers, Charl Daniel |
| Contributors | Esler, K., Boucher, C., Stellenbosch University. Faculty of Science. Dept. of Botany and Zoology. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 184 p. : ill. |
| Rights | Stellenbosch University |
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