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Optimizing soil organic carbon stock assessments for spekboom reforestation of degraded lands in the Eastern Cape, South Africa
Thesis (MScAgric)--Stellenbosch University, 2025.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867614116428906496 |
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| access_status_str | Open Access |
| author | Rheeder, Paul Johan |
| author2 | Rozanov, Andrei |
| author_browse | Rheeder, Paul Johan Rozanov, Andrei |
| author_facet | Rozanov, Andrei Rheeder, Paul Johan |
| author_sort | Rheeder, Paul Johan |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScAgric)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132471 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:46:55.727Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132471 Optimizing soil organic carbon stock assessments for spekboom reforestation of degraded lands in the Eastern Cape, South Africa Rheeder, Paul Johan Rozanov, Andrei Van der Westhuizen, Stephan Stellenbosch University. Faculty of AgriSciences. Dept. of Soil Science. Soils Soils -- Carbon content -- South Africa -- Eastern Cape Soils -- Organic compound content -- South Africa -- Eastern Cape Reforestation -- Climatic factors Carbon sequestration -- Soils -- Measurement Land degradation -- South Africa -- Eastern Cape Soil organic carbon -- Measurement Climate change mitigation Nature-Based Solutions -- Management Spekboom (Portulacaria afra) -- South Africa -- Eastern Cape UCTD Thesis (MScAgric)--Stellenbosch University, 2025. Rheeder, P. J. 2025. Optimizing soil organic carbon stock assessments for spekboom reforestation of degraded lands in the Eastern Cape, South Africa. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/ed0d5243-a2f2-4b23-be27-9cf8fa378971 ENGLISH ABSTRACT: This thesis investigates the optimization of soil organic carbon (SOC) stock assessments to enhance the reliability and accuracy of carbon sequestration verification in large-scale reforestation projects, specifically through spekboom (Portulacaria afra) restoration in the Eastern Cape. The aim is to optimize carbon baseline assessments for reforestation projects under Nature-Based Solutions (NBS) that adhere to Verra standards. By addressing shortcomings in existing methodologies, this research proposes a new, tailored methodology suited for the specific conditions of the Eastern Cape. Degraded landscapes in the Eastern Cape are primarily attributed to overgrazing, leading to significant erosion and loss of topsoil, which holds substantial amounts of carbon. This study developed a robust model that ensures accurate baseline assessments for NBS projects by focusing on the capture of landscape variation while being cost-efficient. By employing advanced sampling techniques, such as Latin Hypercube Sampling (LHS) and Conditioned Latin Hypercube Sampling (cLHS), the model provides the most representative data, enhancing the accuracy and reliability of SOC assessments. The research involved detailed fieldwork across four farms in the Eastern Cape Karoo, where SOC content, bulk density (BD), and other soil properties were measured. The results indicated significant variability in SOC stocks across different landscapes and depths, with areas of canopy closure exhibiting higher carbon stocks compared to degraded areas. These findings highlight the potential for increased SOC stocks through spekboom restoration, contributing to carbon sequestration and climate change mitigation. One of the key innovations of this study is the use of power analysis to determine the minimum number of samples required to detect significant changes in SOC stock. This approach ensures that initial sampling efforts are sufficient to establish a reliable baseline, and monitoring is timed to coincide with when changes in SOC stocks become detectable with the baseline sample size. This methodology not only improves the accuracy of SOC assessments but also optimizes resource use, making it feasible for large-scale reforestation projects. The thesis further discusses the implications of these findings for land management practices and carbon offset projects. By providing a reliable and scalable approach for SOC monitoring, this research supports the development of more effective and accreditable restoration projects. Future research is recommended to focus on the carbon sequestration potential of spekboom at different growth stages to refine the carbon accumulation model and boost investor confidence in such projects. Overall, this study contributes to the field by offering a comprehensive and practical methodology for SOC assessments in reforestation projects, emphasizing the role of spekboom in restoring degraded landscapes and enhancing carbon stocks in the Eastern Cape Karoo. The developed model and methodology have significant implications for improving the reliability of carbon credit generation and supporting sustainable land management practices. AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die optimalisering van grondorganiese koolstof (GOK) inhouds assesserings om die betroubaarheid en akkuraatheid van koolstofsekwestrasie-verifikasie in grootskaalse herbebossingsprojekte te verbeter, spesifiek deur spekboom (Portulacaria afra) herstel in die Oos-Kaap. Die doel is om koolstofbasislynassesserings vir herbebossingsprojekte onder Natuurgebaseerde Oplossings (NBO) te optimaliseer wat voldoen aan Verra-standaarde. Deur tekortkominge in bestaande metodologieë aan te spreek, stel hierdie navorsing ’n nuwe, aangepaste metodologie voor wat geskik is vir die spesifieke toestande van die Oos-Kaap. Degradasie van landskappe in die Oos-Kaap word hoofsaaklik toegeskryf aan oorbeweiding, wat lei tot beduidende erosie en die verlies van bogrond wat groot hoeveelhede koolstof bevat. Hierdie studie het ’n robuuste model ontwikkel wat akkurate basislynassesserings vir NBO-projekte verseker deur landskapvariasie in te sluit, terwyl dit koste-effektief bly. Die voorgestelde metodologie maak gebruik van verbeterde monsterneem-tegnieke en data-analiseprosesse om die ruimtelike variasie van GOK beter te karteer. Hierdie benadering stel voor dat verskillende faktore soos gronddiepte, plantegroei en grondgebruikgeskiedenis in ag geneem moet word om die akkuraatheid van koolstofberamings te verhoog. Die studie beklemtoon ook die belangrikheid van streekspesifieke data om die toepaslikheid van die metodologie te verseker. Daar aangevoer dat die huidige standaarde en metodologieë wat algemeen in koolstofkredietprojekte gebruik word, dikwels nie voldoende is om die komplekse ekologiese en sosio-ekonomiese toestande van die Oos-Kaap aan te spreek nie. Hierdie navorsing poog om die gaping te oorbrug deur ’n wetenskaplik gefundeerde raamwerk te bied wat spesifiek gerig is op die unieke uitdagings van hierdie streek. Deur die beperkinge van bestaande metodologieë aan te spreek en ’n aangepaste oplossing voor te stel, dra hierdie tesis by tot die verbetering van die akkuraatheid en geloofwaardigheid van koolstofsekwestrasie- verifikasie. Dit bevorder die implementering van Natuurgebaseerde Oplossings in die Oos-Kaap, met die potensiaal om beide omgewings- en ekonomiese voordele vir plaaslike gemeenskappe te lewer. Masters 2025-06-09T11:42:01Z 2025-06-09T11:42:01Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132471 en Stellenbosch University xix, 139 pages : illustrations, maps application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Soils Soils -- Carbon content -- South Africa -- Eastern Cape Soils -- Organic compound content -- South Africa -- Eastern Cape Reforestation -- Climatic factors Carbon sequestration -- Soils -- Measurement Land degradation -- South Africa -- Eastern Cape Soil organic carbon -- Measurement Climate change mitigation Nature-Based Solutions -- Management Spekboom (Portulacaria afra) -- South Africa -- Eastern Cape UCTD Rheeder, Paul Johan Optimizing soil organic carbon stock assessments for spekboom reforestation of degraded lands in the Eastern Cape, South Africa |
| title | Optimizing soil organic carbon stock assessments for spekboom reforestation of degraded lands in the Eastern Cape, South Africa |
| title_full | Optimizing soil organic carbon stock assessments for spekboom reforestation of degraded lands in the Eastern Cape, South Africa |
| title_fullStr | Optimizing soil organic carbon stock assessments for spekboom reforestation of degraded lands in the Eastern Cape, South Africa |
| title_full_unstemmed | Optimizing soil organic carbon stock assessments for spekboom reforestation of degraded lands in the Eastern Cape, South Africa |
| title_short | Optimizing soil organic carbon stock assessments for spekboom reforestation of degraded lands in the Eastern Cape, South Africa |
| title_sort | optimizing soil organic carbon stock assessments for spekboom reforestation of degraded lands in the eastern cape south africa |
| topic | Soils Soils -- Carbon content -- South Africa -- Eastern Cape Soils -- Organic compound content -- South Africa -- Eastern Cape Reforestation -- Climatic factors Carbon sequestration -- Soils -- Measurement Land degradation -- South Africa -- Eastern Cape Soil organic carbon -- Measurement Climate change mitigation Nature-Based Solutions -- Management Spekboom (Portulacaria afra) -- South Africa -- Eastern Cape UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132471 |
| work_keys_str_mv | AT rheederpauljohan optimizingsoilorganiccarbonstockassessmentsforspekboomreforestationofdegradedlandsintheeasterncapesouthafrica |