Applying remote sensing and spatial analysis to investigateregime shifts in the Albany Thicket of the Baviaanskloof
dc.contributor.advisor | De Klerk, Helen | en_ZA |
dc.contributor.advisor | Maciejewski, Kristine | en_ZA |
dc.contributor.advisor | Biggs, Reinette, 1979- | en_ZA |
dc.contributor.author | Matowanyika, Danai | en_ZA |
dc.contributor.other | Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Geography and Environmental Studies. | en_ZA |
dc.date.accessioned | 2023-02-23T08:05:03Z | |
dc.date.accessioned | 2023-05-18T07:00:18Z | |
dc.date.available | 2023-02-23T08:05:03Z | |
dc.date.available | 2023-05-18T07:00:18Z | |
dc.date.issued | 2023-03 | |
dc.description | Thesis (MA)--Stellenbosch University, 2023. | en_ZA |
dc.description.abstract | ENGLISH ABSTRACT: Human activities have greatly altered the environment, the scale of impact has led to a new geological epoch - the Anthropocene. Of particular concern in this new era is the possibility for regime shifts: large, persistent changes in the structure and function of ecosystems that can have substantial impacts on human well-being and livelihoods. The Baviaanskloof is a semi-arid ecosystem in Southern Africa that has been substantively transformed by human activities. The Baviaanskloof, is located in the unique Thicket biome, characterized by dense spekboom thicket vegetation (Portulacaria Afra). Remote sensing and geoinformatics tools were used to investigate possible regime shifts in the Baviaanskloof, with a focus on regions classified as Baviaanskloof Thicket biome. The regime shift being investigated is the potential shift from an intact Thicket to a pseudo-Savanna Thicket regime. The thesis combined remotely sensed Enhanced Vegetation Index (EVI) from the MODIS platform as a surrogate of biomass and rainfall data from local weather stations over the period 2000 – 2018, complemented with observations from a field visit in Baviaanskloof Heartland area (BHB) in 2018. The BHB has been an active site for ongoing spekboom rehabilitation initiatives. Analytical tools, Break Detection for Additive Seasonal and Trend (BFAST), Sequential t-Test Analysis for Regime Shifts (STARS) and Green-Brown were used to investigate potential regime shifts. Different tools analysed different aspects of biomass changes in the Baviaanskloof, generally showing persistent decreases. Green-Brown showed that majority of the Baviaanskloof did not experience significant annual changes, but experienced significant seasonal changes. Most of the significant changes were decreases in biomass, with 58% of the Bavianskloof experiencing seasonal decreasing trend.Within the Thicket biome specifically, 77% of the area experienced significant biomass decreases. Majority of the changes occurred in the more arid vegetation classes (Groot Arid Spekboomveld), a possible early warning indicator of what lies ahead for the biome. BFAST and STARS detected two major breaks points in the Thicket biome in 2004 (2001 for STARS) and 2011. BFAST showed a decreasing trend of biomass in between and after both break points. STARS also identified a period of relatively low biomass between 2001 and 2011, a period of relatively higher biomass between 2011 and 2016, and a drastic drop in biomass after 2016 in the Thicket biome. The magnitude of the second break points is bigger than that of the first break points for both models. Spatial mapping of breakpoints showed majority of the Thicket biome (87.91%) experienced at least two break points, mostly negative break points experienced in the drier Groot Arid Spekboomveld regions. The thesis also anaylsed the effect of rehabilitation efforts at specific sites within the BHB. The BHB spekboom plantings of 2010-2013 initially showed an increase in biomass, followed by a decreasing trend. This variations in biomass patterns show that the Baviaanskloof is a complex system with spatial and temporal dynamism. The geoinformatics and analytical tools used in this study provided meaningful insights into investigating possible regime shifts in the Baviaanskloof, and was able to analyse these spatially and detect significant break points. This points to the potential for these tools in detecting regime shifts. | en_ZA |
dc.description.abstract | AFRIKAANSE OPSOMMING: Mensgedrewe aktiwiteite het die omgewing op groot skaal verander. Die skaal van impak het gelei tot 'n nuwe geologiese epog - die Antroposeen. Van besondere kommer in hierdie nuwe era is die moontlikheid vir regime-verskuiwings: groot, aanhoudende veranderinge in die struktuur en funksie van ekosisteme wat wesenlike impakte op menslike welstand en lewensbestaan kan hê. Die Baviaanskloof is ’n halfdor / semi-droë ekosisteem in Suider-Afrika wat wesenlik deur menslike aktiwiteite getransformeer is. Die Baviaanskloof, is geleë in die unieke Albanie-Ruigte-bioom, gekenmerk deur digte spekboom-ruigtegroei (Portulacaria Afra). Afstandswaarneming en geoinformatika-instrumente is gebruik om moontlike regime-verskuiwings in die Baviaanskloof te ondersoek, met 'n fokus op streke wat as Baviaanskloof Ruigte-bioom geklassifiseer is. Die regime-verskuiwing wat ondersoek word, is die potensiële verskuiwing van 'n ongeskonde Ruigte-regime na 'n pseudo-Savanna Ruigte-regime. Die tesis het afstandwaarneembare Verbeterde Plantegroei-indeks (Enhanced Vegetation Index, EVI) vanaf die MODIS-platform gekombineer as 'n surrogaat van biomassa- en reënvaldata van plaaslike weerstasies oor die tydperk 2000 – 2018, aangevul met waarnemings van 'n veldbesoek in Baviaanskloof Heartland area (BHB) in 2018. Die BHB was 'n aktiewe ligging vir voortgesette spekboom-rehabilitasie-inisiatiewe. Analitiese instrumente, Breekbespeuring vir Additiewe Seisoenale en Tendense (Break Detection for Additive Seasonal and Trend , BFAST), Opeenvolgende t-toetsanalise vir regimeverskuiwings (Sequential t-Test Analysis for Regime Shifts , STARS) en Groen-Bruin (Green-Brown) is gebruik om potensiële regimeverskuiwings te ondersoek. Verskillende instrumente het verskillende aspekte van biomassa-veranderinge in die Baviaanskloof ontbloot, wat oor die algemeen aanhoudende afnames toon. Green-Brown het getoon dat die meerderheid van die Baviaanskloof nie beduidende jaarlikse veranderinge ervaar het nie, maar wel beduidende seisoenale veranderinge ervaar het. Die meeste van die beduidende veranderinge was afnames in biomassa, met 58% van die Bavianskloof wat seisoenale dalende neiging ervaar het. Spesifiek in die Albanie-Ruigte-bioom het 77% van die gebied beduidende biomassa-afnames ervaar. Die meerderheid van die veranderinge het plaasgevind in die meer droë plantegroeiklasse (Groot Arid Spekboomveld), 'n moontlike vroeë waarskuwingsaanwyser van wat vir die bioom voorlê. BFAST en STARS het twee groot breekpunte in die Albanie-Ruigte-bioom in 2004 (2001 vir STARS) en 2011 opgespoor. BFAST het 'n dalende neiging van biomassa tussen en na beide breekpunte getoon. STARS het ook 'n tydperk van relatief lae biomassa tussen 2001 en 2011 BFAST en STARS het twee groot breekpunte in die Albanie-Ruigte-bioom in 2004 (2001 vir STARS) en 2011 opgespoor. BFAST het 'n dalende neiging van biomassa tussen en na beide breekpunte getoon. STARS het ook 'n tydperk van relatief lae biomassa tussen 2001 en 2011 geïdentifiseer, 'n tydperk van relatief hoër biomassa tussen 2011 en 2016, en 'n drastiese daling in biomassa na 2016 in die Albanie-Ruigte-bioom. Die grootte van die tweede breekpunte is groter as dié van die eerste breekpunte vir beide modelle. Ruimtelike kartering van breekpunte het getoon dat die meerderheid van die Albanie-Ruigte-bioom in die studie area (87.91%) ten minste twee breekpunte ervaar het, meestal negatiewe breekpunte wat in die droër Groot Arid Spekboomveld-streke ervaar word. Die tesis het ook die effek van rehabilitasiepogings by spesifieke terreine binne die BHB ontleed. Die BHB spekboom-aanplantings van 2010-2013 het aanvanklik 'n toename in biomassa getoon, gevolg deur 'n dalende neiging. Hierdie variasies in biomassapatrone toon dat die Baviaanskloof 'n komplekse sisteem is met ruimtelike en tydelike dinamika. Die geoinformatika en analitiese instrumente wat in hierdie studie gebruik is, het betekenisvolle insigte verskaf in die ondersoek van moontlike regimeverskuiwings in die Baviaanskloof, en was in staat om dit ruimtelik te ontleed en beduidende breekpunte op te spoor. Dit dui op die potensiaal vir hierdie instrumente om regimeverskuiwings op te spoor. | af_ZA |
dc.description.version | Masters | en_ZA |
dc.format.extent | 126 pages : illustrations | en_ZA |
dc.identifier.uri | http://hdl.handle.net/10019.1/127017 | |
dc.language.iso | en_ZA | en_ZA |
dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
dc.rights.holder | Stellenbosch University | en_ZA |
dc.subject.lcsh | Spatial analysis (Statistics) | en_ZA |
dc.subject.lcsh | Remote sensing | en_ZA |
dc.subject.lcsh | Time-series analysis | en_ZA |
dc.subject.lcsh | Social ecology -- South Africa -- Baviaanskloof | en_ZA |
dc.subject.lcsh | Biotic communities -- South Africa -- Baviaanskloof | en_ZA |
dc.subject.lcsh | Environmental management -- South Africa -- Baviaanskloof | en_ZA |
dc.subject.lcsh | Sustainable development | en_ZA |
dc.subject.lcsh | Portulacaria Afra | en_ZA |
dc.subject.lcsh | Regime change | en_ZA |
dc.subject.lcsh | Forest ecology -- South Africa -- Baviaanskloof | en_ZA |
dc.subject.name | UCTD | |
dc.title | Applying remote sensing and spatial analysis to investigateregime shifts in the Albany Thicket of the Baviaanskloof | en_ZA |
dc.type | Thesis | en_ZA |
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