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The combined effect of slash burning and repeated disc harrowing on changes in fuel loading, soil properties, root growth and stand productivity of eucalypts in Mpumalanga : South Africa
Thesis (MSc)--Stellenbosch University, 2019.
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Stellenbosch : Stellenbosch University
2019
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| _version_ | 1867613963559108608 |
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| access_status_str | Open Access |
| author | Goldsmith, Angel Aphelele |
| author2 | Du Toit, Ben |
| author_browse | Du Toit, Ben Goldsmith, Angel Aphelele |
| author_facet | Du Toit, Ben Goldsmith, Angel Aphelele |
| author_sort | Goldsmith, Angel Aphelele |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2019. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/106934 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:29.748Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2019 |
| publishDateRange | 2019 |
| publishDateSort | 2019 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/106934 The combined effect of slash burning and repeated disc harrowing on changes in fuel loading, soil properties, root growth and stand productivity of eucalypts in Mpumalanga : South Africa Goldsmith, Angel Aphelele Du Toit, Ben Stellenbosch University. Faculty of AgriSciences. Dept of Forest and Wood Science. Harrows Eucalyptus Eucalyptus grandis Wildfires -- Prevention and control Thesis (MSc)--Stellenbosch University, 2019. ENGLISH ABSTRACT: In many South African plantation forestry regions, repeated disc harrowing (after clear felling and during stand development) among other objectives is used as a fuel load reduction measure to minimise wildfire damage. This study reports the effects of this treatment on fuel loading, soil properties and stand growth. The implementation of repeated disc harrowing throughout the rotation of Eucalyptus grandis x nitens stands significantly reduced fuel loading of the most active (i.e. the finer) fuel classes. In a fence line study of adjacent experimental plots, repeated disking (BD) was contrasted with non-disking (B0) treatments. Repeated disc harrowing reduced the average oven dried fuel loading of the 1 hour fuel class by 29.0 t ha-1 and that of the 10 hour fuels by 4.3 t ha-1 when compared to the non-disked treatments. Repeated disc harrowing significantly altered the forest floor structure. The non-disking treatment consisted of the litter (L), fermented (F), and humus (H) strata on top of the mineral soil (MS) layer. Following numerous harrowing application in the BD treatment, the forest floor structure was reduced to only a sparse L layer directly on top of the MS layer. This indicated a considerable change in fuel loading and forest floor structure as a result of disc harrowing. Repeated disc harrowing significantly increased topsoil exchangeable cation quantities, S-value, and reduced bulk density. Topsoil exchangeable K, Ca, Mg, Na, and S-valueincreased by 0.04, 0.34, 0.12, 0.01 and 0.51 cmolc kg-1 respectively following repeated disking. The topsoil pHKCl, extractable P, total N and C were not significantly different among the two treatments. The above and below ground tree growth variables examined in this fence line study indicated no significant differences following repeated disc harrowing treatment. The BD treatment exhibited similar stand density of 1168 stems ha-1 over 1141 stems ha-1 for B0 treatment. Likewise, stand productivity was similar among treatments, with basal area, volume, and plant biomass in the B0 treatment being 24.6 m2 ha-1, 212.5 m3 ha-1and 134.4 t ha-1 versus 23.5 m2 ha-1, 202.6 m3 ha-1 and 127.5 t ha-1 for the BD treatment. Using a profile wall root study method, B0 treatment was observed to have a non-significantly higher root count of 30% on the top 10 cm soil depth when contrasted to BD treatment, which was 22% (percentage of the total root count on a 1 x 1 m vertical profile wall). All the differences observed on the tree growth and stand productivity parameters among the two treatments were not significant at (p<0.05). The negligible growth reduction in repeatedly disked treatment is surpassed by the significant fuel load reduction and reduced wildfire risk. AFRIKAANSE OPSOMMING: ʼn Aantal bosboustreke in Suid-Afrika eg stroke grond met ʼn skotteleg na kaalkap (maar daarna ook herhaaldelik gedurende die rotasie), ten einde brandstof lading te verminder en sodoende skade deur veldbrande te beperk. In hierdie studie word die effek van hierdie behandeling op brandstoflading, grondeienskappe en opstandsgroei ondersoek. Herhaalde eg operasies gedurende die rotasie in Eucalyptus grandis x nitens opstande het gelei tot vermindering in brandstof lading van die aktiefste (d.w.s die fynste) brandstofklasse. In 'n studie van aangrensende persele is herhaalde egting (BD) gekontrasteer met onbewerkte (B0) behandelings. Die oonddroë brandstoflading van die 1 uur brandstofklas is deur herhaalde egting verminder met 29,0 t ha-1 en die brandstof van 10 uur klas met 4,3 t ha-1 vergeleke met die onbewerkte persele. Herhaalde egting het ook ʼn wesenlike verandering in die struktuur van die bosvloer teweeggebring. Die onbewerkte behandeling het bestaan uit die onlangs gekapte materiaal (L – laag), gefermenteerde (F) en humus (H) laag bo-op die minerale grondlaag (MG). Na 'n gereelde egting in die BD-behandeling, is die bosvloer struktuur verskraal tot slegs 'n ylerige L-laag direk bo-op die MG-laag. Dit dui op 'n aansienlike verandering in brandstoflading en bosvloerstruktuur as gevolg van herhaalde egting. Herhaalde egting het die hoeveelheid uitruilbare katione, die S-waarde en die bulkdigtheid van die bogrond beduidend verhoog. Die bogrondse uitruilbare K, Ca, Mg, Na en S-waarde het met herhaalde egting onderskeidelik met 0.04, 0.34, 0.12, 0.01 en 0.51 cmolc kg-1 gestyg. Die bogrondse pHKCl, ekstraheerbare P, totale N en organiese koolstof het nie beduidend verskil tussen die twee behandelings nie. Bogrondse en ondergrondse boomgroeiveranderlikes wat in aangrensende persele ondersoek is, het nie beduidend verskil tussen behandelings nie. Die BD-behandeling se opstandsdigtheid van 1168 stamme ha-1 was vergelykbaar met die 1141 stamme ha-1 vir die B0-behandeling. Net so was die maatstawwe van opstandsproduktiwiteit nie betekenisvol verskillend (p<0.05) tussen die behandelings nie. Die basale oppervlakte, volume en biomassa in die B0-behandeling was 24.6 m2 ha-1, 212.5 m3 ha-1, en 134.4 t ha-1 teenoor waardes van 23.5 m2 ha-1, 202.6 m3 ha-1, en 127.5 t ha-1 vir die BD-behandeling. Met behulp van 'n profielgat wortelstudiemetode is daar waargeneem dat die B0-behandeling ʼn effens hoër worteltelling van 30% in die grondlaag van 0-10 cm het, in teenstelling met BD-behandeling, wat 22% was. Hierdie effek was egter nie betekenisvol nie. Die weglaatbaar klein negatiewe effek op opstandsgroei na herhaalde egting word oorskadu deur die aansienlike vermindering van die brandstoflading en die gepaardgaande verlaging in die brandrisiko. Masters 2019-11-15T11:06:04Z 2019-12-11T06:39:33Z 2020-07-21T03:00:12Z 2019-12 Thesis http://hdl.handle.net/10019.1/106934 en_ZA Stellenbosch University 123 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Harrows Eucalyptus Eucalyptus grandis Wildfires -- Prevention and control Goldsmith, Angel Aphelele The combined effect of slash burning and repeated disc harrowing on changes in fuel loading, soil properties, root growth and stand productivity of eucalypts in Mpumalanga : South Africa |
| title | The combined effect of slash burning and repeated disc harrowing on changes in fuel loading, soil properties, root growth and stand productivity of eucalypts in Mpumalanga : South Africa |
| title_full | The combined effect of slash burning and repeated disc harrowing on changes in fuel loading, soil properties, root growth and stand productivity of eucalypts in Mpumalanga : South Africa |
| title_fullStr | The combined effect of slash burning and repeated disc harrowing on changes in fuel loading, soil properties, root growth and stand productivity of eucalypts in Mpumalanga : South Africa |
| title_full_unstemmed | The combined effect of slash burning and repeated disc harrowing on changes in fuel loading, soil properties, root growth and stand productivity of eucalypts in Mpumalanga : South Africa |
| title_short | The combined effect of slash burning and repeated disc harrowing on changes in fuel loading, soil properties, root growth and stand productivity of eucalypts in Mpumalanga : South Africa |
| title_sort | combined effect of slash burning and repeated disc harrowing on changes in fuel loading soil properties root growth and stand productivity of eucalypts in mpumalanga south africa |
| topic | Harrows Eucalyptus Eucalyptus grandis Wildfires -- Prevention and control |
| url | http://hdl.handle.net/10019.1/106934 |
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