Silvicultural value chain analysis of short rotation Eucalyptus grandis x urophylla stands in coastal Zululand

Graham, Daniel John (2018-03)

Thesis (MScFor)--Stellenbosch University, 2018.

Thesis

ENGLISH ABSTRACT: Intensive silvicultural management at establishment is part of commercial practises on short rotation Eucalyptus spp. plantations in South Africa. There is however some uncertainty within the industry whether or not particular activities at plantation level add higher value to the product than the initial investment cost. This study is divided into two sections. Firstly, a case study research method is performed to identify if historical operational data can be used to determine the effect of silvicultural activities on the early height growth and rotational performance of Eucalyptus grandis x urophylla stands in coastal Zululand. The relationship between silvicultural activities and the final tonnes harvested at end of rotation was determined by means of robust regression analysis. Secondly, Microsoft Excel Solver was used to build an optimization simulation model. The model is based on the results from the analysis in the first section. The optimization model provides the lowest cost, highest production and most profitable path through the silvicultural value chain for Zululand North and South respectively. The results from the first section illustrated the important impact that site, climate and other external factors have on the growth and performance of stands, and that stands in Zululand South perform better than stands in Zululand North. Results also indicated that site specific silviculture is very important, with some silvicultural activities showing significantly positive effects on the final tonnes harvested in one region, while the same activities did not have a significant effect in the other region. Results from the operational data analysis were compared to results from published trial research studies. Results related to the effect of pre-plant spray and planting with water on early survival, the effect of fertiliser on final volume growth in Zululand South and the effect of number of weedings on early height growth in Zululand South were contradictory to research studies. The effect of planting with water on early height growth in Zululand North, effect of planting season in both regions and the effect of blanking on final tonnes in Zululand South correlated to results from published research studies. It seems that operational data in the current format is not suitable to demonstrate cause and effect of silvicultural activities. Small changes to operational data collection protocols could enhance the research use of this data substantially. The Excel Solver simulatution model is based on the results of the first section and is only used to illustrate the potential it can have in future management decisons. Results from the Excel Solver simulation illustrated that the highest production and most profitable path is the same path through the silvicultural value chain in Zululand North and in Zululand South. The activities included in these paths did however differ between the two regions. The most profitable path through the silvicultural value chain in Zululand North illustrated a potential cost-benefit of R4716.62 ha-1, while the most profitable path through the silvicultural value chain in Zululand South illustrated a potential cost-benefit of R159.31 ha-1.

AFRIKAANSE OPSOMMING: Intensiewe boskultuur bestuur tydens vestiging van kort-rotasie Eucalyptus plantasies word kommersiël toegepas in Suid-Afrika. Daar is egter 'n mate van onsekerheid in die bedryf of al die aktiwiteite op plantasievlak hoër waarde toevoeg by die finale produk as die aanvanklike beleggingskoste. Die studie is in twee afdelings verdeel. Eerstens word 'n gevallestudie-navorsings metode uitgevoer om te identifiseer of historiese operasionele data gebruik kan word om die effek van boskultuur aktiwiteite op die korttermyn hoogte groei en die rotasie produktiwiteit van vakke te bepaal. Die verhouding tussen die effek van boskultuur aktiwiteite en die finale tonne geoes aan die einde van rotasie is bepaal deur middel van robuuste regressie-analise. Tweedens word Microsoft Excel Solver gebruik om 'n optimaliserings simulasie model te bou. Die model is gebaseer op die resultate van die analise in die eerste afdeling. Die optimaliseringsmodel bied die laagste koste, hoogste produksie en mees winsgewende pad deur die boskultuur waardeketting vir Zululand Noord en Suid onderskeidelik. Die resultate van die eerste afdeling illustreer die belangrike impak wat die terrein, klimaat en ander eksterne faktore het op die groei en prestasie van vakke, en dat vakke in Zululand Suid beter presteer as vakke in Zululand Noord. Resultate het ook aangedui dat terrein spesifieke boskultuur baie belangrik is, aangesien sommige boskultuur aktiwiteite betekenisvolle positiewe effekte toon op die finale tonne geoes in een streek, terwyl dieselfde aktiwiteite nie in die ander streek betekenisvolle effekte gehad het nie. Resultate van die operasionele data-analise is vergelyk met die resultate van gepubliseerde proefnavorsingstudies. Die effek van voorplantspuit en plant met water op vroeë oorlewing, die effek van kunsmis op die finale volume groei in Zululand Suid en die uitwerking van die aantal onkruidbeheer aktiwiteite op vroeë hoogtegroei in Zoeloeland Suid is teenstrydig met wat gevind is navorsingstudies. Die effek van plant met water op vroeë hoogtegroei in Zululland Noord, die effek van plantseisoen in albei streke en die effek van inboeting op finale tonne in Zululand Suid, korreleer met resultate van gepubliseerde navorsingstudies. Dit blyk dat operasionele data in die huidige formaat nie geskik is om oorsaak en gevolg van boskultuur aktiwiteite te toon nie. Klein veranderinge aan operasionele data-insamelingsprotokolle kan die navorsingsgebruik van hierdie data substansieel verbeter. Die Excel Solver simulasie is gebaseer op die resultate van die eerste afdeling en word slegs gebruik om die toekomstige potensiaal vir bestuursbesluite te illustreer. Resultate van die Excel Solver simulasie model het getoon dat die hoogste produksie- en mees winsgewende roete dieselfde roete is deur die boskultuur waardeketting in Zululand Noord en in Zululand Suid, onderskeidelik. Hierdie roetes het egter tussen die twee streke verskil. Die mees winsgewende roete deur die boskultuur waardeketting in Zululand Noord het 'n potensiële kostevoordeel van R4716.62 /ha geïllustreer, terwyl die mees winsgewende roete deur die boskultuur waardeketting in Zululand Suid 'n potensiële koste-voordeel van R159.31 /ha geïllustreer het.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/103906
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