Innovation in ecological restoration techniques: Enhancing Portulacaria afra survivorship in degraded arid thicket
- Authors: Norman, Yondela Masande
- Date: 2023-03-31
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419276 , vital:71630
- Description: The Albany Thicket Biome has undergone extensive degradation over the past century, particularly from overstocking of livestock in the arid types of thicket. The degradation of the biome, coupled with little to no natural recovery, prompted the South African Government to implement the Subtropical Thicket Restoration Programme (STRP) in the early 2000s to rehabilitate degraded thicket using unrooted Portulacaria afra truncheons. The STRP also sought to create job opportunities, bring about social upliftment, promote biodiversity conservation and incentivise farmers and landowners in the region to promote carbon trading and farming of P. afra using carbon credits. However, the survivorship of P. afra planted using the STRP planting protocol has been less than ⁓30% because they are planted in degraded areas, where the truncheons are subjected to harsh biophysical conditions such as hard, capped soil, high soil temperatures, drought and herbivory. The aim of this study, therefore, was to improve the survivorship of P. afra planted in degraded thicket to at least 30%, using modified planting methods. In this study, four treatments were applied in 210 pondings (or micro-dams), each with P. afra planted in them (the first three treatments used rooted cuttings). The first treatment involved watering regimes where pondings were watered at varying frequencies. The second treatment involved planting companion species alongside P. afra while the third treatment involved planting P. afra underneath a nurse canopy. In the fourth treatment, unrooted P. afra truncheons were planted inside pondings. The mean survivorship of the P. afra cuttings was assessed 18 months after planting. The watering regime treatments, including the control, all yielded a survivorship of over 75%, with the significantly highest levels of survivorship being displayed in the weekly watering treatment (90.9 ± 6.8%) (p < 0.01). The companion plant treatment also produced a high mean survivorship of P. afra (94.9 ± 3.6%), significantly higher than that of the nurse plants (87.5 ± 6.3%) (p < 0.01). Among the unrooted truncheons it was found that untreated truncheons had the highest survivorship (76.2 ± 17.6%), with the lowest mean being found in truncheons that were both pruned and scarified (70.8 ± 20.8%), suggesting that this treatment, out of all of them, is the least successful under the prevailing environmental conditions in the study area. However, there was no significant differences among the unrooted truncheon treatments and their respective survivorship values to further substantiate this assertion (p = 0.26). Findings in this study also suggest that planting P. afra cuttings under a nurse plant was ideal for P. afra survivorship due to the nurse plant’s ability to ameliorate the microclimate under which the cuttings can establish and grow. Despite the soil under the nurse canopy having a significantly lower mean soil water potential (-160.9 ± 200.5 kPa), compared to the open areas (-73.4 ± 55.7 kPa) (p = 0.04), the pondings under the nurse canopy still had a lower mean soil temperature (31.4 ± 5.25°C) than the treatments in the open areas (38.5 ± 2.7°C), during the harsh midday sun. These favourable characteristics are reflected in the P. afra cuttings under a nurse canopy having a higher chlorophyll fluorescence (0.76 ± 0.06). compared to those planted in open areas (0.73 ± 0.13), suggesting that the P. afra cuttings in the former treatment had a higher photosynthetic efficiency compared to those in the latter, despite there being no statistically significant difference in chlorophyll fluorescence between the treatments (p = 0.14). Although these findings suggest that applying these modifications to planting P. afra, having achieved its objective of increasing survivorship to well over 50%, is likely to produce favourable results not only in overall survivorship, but also in fast-tracking arid thicket rehabilitation and restoration, further research on these rehabilitation techniques and their effectiveness is required. Furthermore, the downside to these treatments is that they are costly and time consuming, which puts the feasibility of large-scale programmes using these applications into question. Further investigation is required to determine ways in which the cost-effectiveness of these applications can be enhanced. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
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- Date Issued: 2023-03-31
Crop fields abandonment: assessing the dynamics of degradation in relation to leverage points for sustainable land management in the Macubeni catchment, South Africa
- Authors: Sibiya, Silindile
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422470 , vital:71945
- Description: Soil erosion is a major global environmental problem and a pervasive forms of land degradation that threatens land productivity and food and water security. Some of the biggest sources of sediment in catchments are previously cultivated lands. Regardless of this factor, the abandonment of cultivated fields is not well-researched. Sustainable land management (SLM) interventions can play a significant role in mitigating and halting land degradation. This study investigated the dynamics of degradation exhibited by crop fields and the potential impacts of SLM interventions, using a leverage points framework and a case study in the Macubeni catchment of South Africa. The research answers three questions: (1) What is the relationship between the usage status of crop fields and degradation in Macubeni? (2) What are the drivers of crop field abandonment and how do they interact in the system? (3) Can proposed sustainable land management interventions tackle the dynamics of land abandonment, and associated degradation, at the root cause level? An empirical-analytical approach using a four step multi-method process was followed, in which crop fields were mapped using ArcGIS tools, literature was reviewed alongside stakeholder engagements, qualitative systems mapping modelling was undertaken, and a Multi-Criteria Analysis (MCA) with leverage points hierarchy was used to integrate all the steps together. The results revealed that the various drivers of crop field abandonment include natural environmental factors, socio-economic and social factors. 47.41% of the total crop fields in Macubeni were classified as highly degraded, and abandoned fields covered 37.47%. The statistical Chi-Square Test also confirmed that there is a significant relationship between the usage status and degradation level in crop fields. The SLM interventions assessed in the study have the potential to tackle the dynamics of land abandonment at a root cause level, however, there is a need to first shift the community’s mental models to address the existing sources of change resistance that are hindering successful implementation. Furthermore, the innovative multi-method approach applied in this study can further provide a holistic, dynamic, and integrated decision-support to land conservation and rehabilitation projects in similar settings across South Africa and other developing countries as opposed to the more traditional one-dimensional approaches. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
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- Date Issued: 2023-03-29
Factors influencing the number of non-timber forest product species used at the individual, household and village levels in Vhembe, Limpopo Province, South Africa
- Authors: Mulaudzi, Takalani Rachel
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422481 , vital:71946
- Description: Non-Timber Forest Products (NTFPs) are wild biological resources obtained from natural landscapes, agricultural systems, and rural and urban regions for a variety of uses. NTFPs contribute significantly to livelihoods and living standards by offering a variety of socioeconomic benefits such as food, health, income generation, and safety nets. These multiple benefits are provided by a wide diversity of plant, animal and fungal species in different settings. However, the precise number of NTFP species used depends on the scale of assessment, namely use by individuals, by households and by villages. Consequently, it is difficult to compare numbers of species used between studies because of the differing scales. As a result, the objective of this study was to determine the number of NTFP species used at three different scales and how each is correlated with appropriate scale-dependent contextual variables. This objective was met by sampling individuals and whole households in five villages in the Vhembe District in Limpopo Province, South Africa. Twenty households were randomly selected in each village, providing a total sample of 100 households and 179 individuals in those households. In each household, every adult member was interviewed individually about the NTFPs that they used or knew. The major questions covered the NTFP species used, the respondents' socioeconomic level, the NTFP species used previously, and if the number of NTFP species are changing in the landscape. Data were reported per individual as well as per household and per village. The household level was derived by adding the responses of all the adults in each household but excluding duplicates. The same approach was used at the village scale, namely, the data across the 20 households were pooled, and duplicates were omitted. Patterns of NTFP use were examined by type of NTFP, and analysis using standard statistical tests, along with a Principal Components Analysis and a multivariate Detrended Correspondence Analysis of the NTFP species composition across villages. A total of 275 species of NTFPs were mentioned across the entire sample, including 81 species of firewood, 48 species of edible insects, 43 species of wild vegetables, 40 species of edible fruits, 38 species of wood utensils, 28 species of medicinal plants, 23 species of thatch grass, 19 species of poles, 19 species of wood for carvings, nine species of reeds, eight species of mushroom, and eight species of fodder. Of these species, some species had more than one use. Approximately 90% of the species used by the respondents were native species. Wild vegetables (e.g., Corchorus olitorius, Amaranthus capensis, Bidens pilosa), firewood (e.g., Colophospermum mopane, Parinari curatellifolia, Combretum hereroense), wild fruit (e.g., Landolphia kirkii, Vangueria infausta), and edible insects (e.g., Imbrasia belina, Macrotermes michaelseni, Encosternum delegorguei) were the most often used NTFPs by communities in the Vhembe area. Most of the households relied on NTFPs for subsistence. At the scale of an individual, the mean number of NTFP species used was 26.8±12.6 across the five villages. When considering a household, the mean number was 36.1±10.7 species. When aggregated across the 20 households per village, the mean number per village was 105.2±34.1 species. The species accumulation curve showed that 20 households per village were reasonably representative for four of the five villages. The results from the principal component analysis (PCA) and correlation analysis revealed that age, education, and employment status were significantly associated with the number of species used by individuals, whereas gender showed no clear correlation. At the household scale, household size was positively related with the number of species used, but income level and income source were not. At the village scale, attributes such as proximity to a town, settlement type, vegetation type, and distance to a nearby savanna all had some influence on the number of NTFP species listed. Most of the respondents felt that the number of species used had increased over the last 10–15 years, although some stated the opposite. Increases were attributed by traditional councils bans, the establishment of protected areas, and restoration. Activities eroding the number of NTFP species were identified as clear felling for farming, climate change, and over-harvesting. This study suggests that communities must be made more aware of the overharvesting of NTFP species in the savanna to avoid biodiversity loss. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
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- Date Issued: 2023-03-29
Knowledge of and concern about global biodiversity loss vs local biodiversity loss in the Maputaland-Pondoland-Albany Hotspot (MPA)
- Authors: Toyisi, Zanele Jacqueline
- Date: 2022-10-14
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/365025 , vital:65671
- Description: Biodiversity forms the basis of the ecosystem services that society depends on. However, humanity has caused an increase in the extinction rates up to 100 times higher than that of evolutionary background levels. Recent studies found that biodiversity conservation becomes successful when it is grounded in local support. Support for conservation of biodiversity depends on peoples’ knowledge of biodiversity, their attitudes and awareness of the number of species that are present and that are threatened with extinction. However, some studies have shown that the public has little knowledge about the concept of biodiversity and have poor biodiversity identification skills. There is growing concern that people know and are more concerned about global biodiversity loss than what is happening around them locally. The notion that people know and are more concerned about global biodiversity loss rather than local, has not been deeply studied. Most studies have been in developed countries, with limited studies in developing countries and countries that have high diversity such as South Africa. Having accurate knowledge about biodiversity and the environment is said to be the key predictor of intention to change behaviour in relation to biodiversity. Therefore, the purpose of this study was to understand the knowledge and concern (if any) people have of biodiversity at global and local scales. More so, it set out to determine how familiar people are with the term biodiversity, what they consider as forces leading to biodiversity decline, the level of concern that they have for biodiversity loss and if knowledge and concern is influenced by demographic profiles. To achieve this aim, a total of 220 random interviews were conducted in three towns within the Maputaland-Pondoland-Albany Hotspot in South Africa. The results show that respondents are familiar with the term biodiversity. There was a strong relationship between having heard of the term and the ability to define it with 55 % of the respondents aware of it and able to define it. Respondents had moderate knowledge general knowledge related to biodiversity. Gender, education and childhood background did play a role in the knowledge of biodiversity. Women had more knowledge about biodiversity than men, highly educated respondents knew more and the youth knew more than older respondents. The results of this study found that there were no respondents who could not name any local species from South Africa. However, things changed at global level with 32 % of the participants unable to name species at global level. Endangered species are still relatively unknown, as the majority of respondents could not name any at district (84 %) or at global level (61 %). Charismatic species were known the most by respondents as 52 % mentioned them at national level and 59 % at global level. This study also assessed if there is concern for biodiversity loss. The results showed that there is concern for biodiversity with 71 % of the respondents in support for conservation and 60 % of the respondents willing to donate towards conservation. This study found that reasons for conservation related to the level of products consumed directly from the environment. Those that supported conservation for use values consumed more products from the environment than those who were in support for non-use values. Furtherly, this study found that women were more concerned about biodiversity loss than men. Highly educated respondents were more concerned and the youth was not. Furtherly, this study found that knowledge about biodiversity loss corelated with concern. For example, women had more knowledge and were more concerned about biodiversity loss. Overall, this study has shown that there is some knowledge and concern that people have about biodiversity and its loss. This can assist the relevant policy makers and researchers to know where intervention is needed to increase the knowledge that people have of biodiversity loss and which aspects of biodiversity people are most concerned about. This is so that new policies and conservation measures can include what is appealing to the local people so that support for conservation can be built and accepted by local people. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2022
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- Date Issued: 2022-10-14
The distribution and perceptions of invasive alien plants in small towns in the Eastern Cape province, South Africa
- Authors: Seboko, Tshepiso Collen
- Date: 2022-10-14
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/${Handle} , vital:65669
- Description: Invasive alien plants (IAP) of different life forms have major effects on biodiversity, ecosystem functioning, economies, and livelihoods worldwide. There is evidence that IAP are rapidly increasing around the world, and the negative impacts associated with them are expected to worsen due to continuing land transformation, climate change, and urbanisation. Yet, information on the distribution, abundance, knowledge, and perceptions of IAP is limited, especially in small towns. Most previous research has largely focused on rural settings and larger cities, thus hindering the effective control and management of IAP in smaller urban settings. It is therefore important to assess the distribution of IAP to provide useful information to guide clearing and mitigation efforts to reduce the impacts and proliferation of IAP in smaller urban settings. Consequently, the aim of the study was to determine the distribution, composition, abundance, and perceptions of woody IAP in small towns in the Eastern Cape province of South Africa and assess how and why they may differ within and between towns. To achieve this aim, a drive by road survey was undertaken across all suburbs and land use types in 12 small towns located in the Eastern Cape province of South Africa. The 12 randomly selected small towns were, Adelaide, Alexandria, Barkley East, Bedford, Burgersdorp, Cathcart, Kirkwood, Middelburg, Paterson, Somerset East, St. Francis Bay and Willowmore. All woody IAP visible from the surveyed roads were counted across all suburbs and land use types within each town. A total of 38 427 woody IAP were enumerated, with 56 species across different land use types and suburbs in all towns. Affluent suburbs accounted for 58% of the IAP enumerated, while the Reconstructed Development Programme (RDP) suburbs accounted for only 5%. In terms of the land use type, most of the IAP were encountered in the residential areas (54%), as compared to, road verges (32%) and public urban green spaces (PUGS) (14%). Of the 12 towns, Middleburg had the highest number of woody IAP, with 5 573 individuals, while Paterson had the lowest number with 947. The most common IAP species across all towns was Melia azedarach with 4 384 individuals, followed by Pinus elliotti (4 051), and Jacaranda mimosifolia (3 640). Spathodea campanulata, Ardisia crenata, and Parkinsonia aculeata had the lowest number of individuals with only two individuals each across all towns. This study also assessed the knowledge, perceptions, and willingness of urban residents to control IAP in their home yards using household surveys. A total of 240 household surveys were administered in the 12 towns. The results showed that more than half of the respondents (59%) had no knowledge of IAP, while 14% had neutral knowledge and only 2% had high knowledge. Forty percent of the respondents agreed that IAP pose a problem to the environment whilst 11% did not think IAP posed a problem to the environment, and 49% stated that they do not know. Most of the respondents (91%) perceived IAP positively, and stated that they benefit from the IAP, with the most mentioned benefit being shade (50%). Almost two-thirds of the respondents (65%) were willing to report on the IAP in their yards to the relevant authorities that deal with the control and management of IAP. Over half (56%) of the respondents were willing to have the IAP removed from their gardens, with the most stated reason for removal was because the IAP caused damage to property (13%). Respondents thought that the local government (35%) or district government (30%) should be responsible for the control and management of IAP. Overall, the study showed that IAP species were most common in residential land use type and affluent suburbs. These findings can assist the relevant authorities that deal with IAP, regarding which plant species, suburbs, and land use types to prioritise regarding awareness and investment for control and management. This will also help explore alternative indigenous species that can be used as replacements that may offer the same benefits derived from IAP by urban residents. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2022
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- Date Issued: 2022-10-14
Mediating transition to household electricity conservation through co-designing in Makhanda, South Africa
- Authors: Mutumbi, Uzziah
- Date: 2022-04-06
- Subjects: Households Energy consumption South Africa Makhanda , Renewable energy sources South Africa , Consumer behavior South Africa Makhanda , Energy conservation South Africa Makhanda Citizen participation , Low-income consumers South Africa Makhanda
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291262 , vital:56838
- Description: Households consume up to 20% of total global electricity consumption, hence they are important role players in efforts for promoting sustainable consumption. Research on electricity-use behaviour and effectiveness of interventions is important for informing intervention strategies. However, relative to developed countries, research on this subject is lacking in developing countries, where electricity access is limited, and a substantial proportion of households are energy poor. The main goal of this study was to examine reported electricity-use behaviour and the effects of co-designed interventions on household electricity consumption in low-income households in Makhanda, South Africa, using a field-based experiment. Findings from self-reported electricity-use practices showed mixed results, with households reporting both good electricity-use behaviour (e.g., cooling down hot food before refrigeration) and wasteful actions (e.g., leaving appliances on standby). Results showed that electricity-use behaviour was influenced by socio-psychological values including universalism, benevolence, hedonism, and power. Over the intervention period, households exposed to co-designed electricity-saving interventions showed mean electricity savings of about 5.5%, while households in the Partial Treatment and Control group showed increased electricity consumption. Socio-demographic factors such as age and psychological factors (involvement and perceived behavioural control) were very important determinants of household consumption. Broadly, the findings empirically validate the impact of collective problem formulation and co-designing interventions in promoting sustainable actions. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2022
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- Date Issued: 2022-04-06
Soil and vegetation recovery following Acacia dealbata clearing in the Tsitsa catchment, Eastern Cape Province of South Africa: implications for ecological restoration
- Authors: Balintulo, Putuma
- Date: 2022-04-06
- Subjects: Acacia South Africa Eastern Cape , Invasive plants South Africa Eastern Cape , Working for Water Programme , Soil restoration South Africa Eastern Cape , Plant nutrients South Africa Eastern Cape , Restoration ecology South Africa Eastern Cape , Clearing of land South Africa Eastern Cape , Legacy effect
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/290778 , vital:56783
- Description: Invasion by alien plant species in South Africa continues to compromise the stability of ecosystems by causing declines in biodiversity, altering soil nutrients and processes, and subsequently transforming ecosystem functionality. Control of invasive alien plant species has been widely implemented in South Africa to minimize their negative impacts; however, the legacy effects can persist long after the plant has been removed. The impacts of Acacia dealbata clearing on soil properties and native vegetation recovery remains understudied despite their significance in ecological restoration and monitoring. This comparative study determined the impacts of A. dealbata clearing on both soil physicochemical properties and vegetation in the Eastern Cape Province of South Africa. Soils were collected from three different clearing treatments, namely, cleared, invaded, and uninvaded, on 5 m x 5 m plots over three summer months. The plots were replicated four times for each clearing treatment, making a total of 72 sampling plots. Soils were assessed for soil pH, resistivity, P, C, N, and exchangeable cations as well as soil moisture content, penetration resistance, infiltration rate, hydraulic conductivity, and water repellency. Clearing of A. dealbata did not have any significant effects on most soil nutrients, however, there were variations in soil pH, resistance, and Na. Soil pH was significantly higher in the uninvaded treatments than in the cleared and invaded treatments. Soil moisture content was significantly higher in the cleared treatments than the adjacent invaded and uninvaded treatments, but this was observed in the month of December only. Soil penetration resistance and infiltration rates were significantly higher in the month of December in the cleared treatments. For all clearing treatments, no significant differences were recorded for soil hydraulic conductivity. These results on changes in soil properties following A. dealbata clearing are varied, with some soil properties showing decreases, an indication that removal of A. dealbata has the potential to shift soil properties towards a positive recovery trajectory. This study further assessed whether the clearing of A. dealbata facilitates the recovery of native plant species. Vegetation surveys were conducted in the three above-mentioned treatments and plots. Results showed little recruitment of native grasses and forbs, but the persistence of A. dealbata seedlings in the cleared treatments. Species richness and Shannon-Wiener diversity index were significantly (P < 0.05) higher in the cleared and invaded treatments than the uninvaded treatments, and this was more visible for trees and shrubs. Cover for all species was significantly higher (P < 0.05) in the uninvaded than the cleared and invaded treatments. This study observed the recruitment of some native species in the cleared treatments that were not present in the invaded treatments. Therefore, the recruitment and establishment of some native species, mostly grasses, in the cleared treatments gives assurance that passive restoration is on a positive vegetation recovery trajectory that can lead to recovery of native vegetation after A. dealbata clearing. Therefore, the study concludes that investing in ecological restoration after alien plant clearing is a necessity for complete ecosystem recovery to be achieved. Overall, the study concludes that the removal of A. dealbata triggers changes to some soil properties. Similarly, the study observed recruitment of some native grasses in cleared areas, an indication that alien plant clearing facilitates changes in both soil properties and vegetation. However, soil and vegetation recovery are being hampered by the regrowth of A. dealbata and secondary invaders that were observed in the cleared treatments. Two key recommendations of this study are (i) clearing follow-up to remove recruiting seedlings of invasive plant species and secondary invaders should be timeous and well-funded, and (ii) active restoration should be considered to speed-up soil and vegetation recovery processes. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2022
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- Date Issued: 2022-04-06
Household food waste generation, disposal and minimisation in two South African towns
- Authors: Mtakati, Sinako
- Date: 2022-04
- Subjects: Food waste South Africa Cradock , Food waste South Africa Middelburg (Eastern Cape) , Sanitary landfills Environmental aspects South Africa , Greenhouse gases Environmental aspects South Africa , Income distribution South Africa , Socio-economic status South Africa , Waste minimization South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/232159 , vital:49967
- Description: Food waste is becoming an important issue considering greenhouse gas emissions from landfills. However, data on the quantities of food disposed remains limited, especially for developing, countries including South Africa. Global food waste estimates suggest that households in developed countries waste more food than those in developing countries. Further, research shows that lack of food waste management impacts negatively on the global efforts to combat food waste generation. I therefore set out to present primary data relating to household food waste generation and minimisation within a South African context. The case study covers two towns in the Eastern Cape province, namely Cradock and Middelburg, with a combined population of 55 352 people. Household food waste assessment and quantification was undertaken using two methods, 1) questionnaires to explore quantities of different types of food wasted by households, and 2) kitchen scales to measure the amounts of food discarded by households. Participating households in each suburb were selected randomly. Differences in shopping and household food waste behaviour in households from different income suburbs is vital to understand as it sets an effective approach to food waste interventions that might have a positive impact in minimising food waste generation. In this thesis, differences in shopping and household food waste behaviour across households in the affluent, middle and low-income suburbs is uncovered. A questionnaire was conducted and households in the affluent suburbs purchased food more frequently and had the highest percentage of respondents that used shopping list when buying food than those in the middle and low-income suburbs. The thesis also indicates that households in the low-income suburbs were more attracted to food special offers and had a higher proportion of respondents who could not distinguish between “Use by” and “Best before” dates than those in the affluent and middle- income suburbs. The reasons to food waste generation overlap between the towns. However, between the suburbs, the respondents from households in the affluent suburbs pointed that they were mainly generating and disposing food waste because they did not think it is an issue. Excessive cooking and food expiring before being consumed were found to be the most common reasons for food waste generation and disposal among households in the low and middle-income suburbs. The times which households are likely to generate more food waste were investigated. Nonetheless, only a few households indicated that there were times that they generated and disposed more food in the bins. The most cited times in the affluent suburbs were during Christmas (54%) and in summer (41%). Festive season (65%) and traditional ceremonies (37%) were the most cited times in the middle-income suburbs, while festive season (46%) and the summer season (36%) were the most cites among households in the low- income suburbs. The dimensions of shopping and household food waste behaviour is reflected in the types and quantities of food waste generated. The results reveal that vegetables were the most wasted food type in Cradock (26%) and in Middelburg (30%), while tinned food and dairy were the least discarded food types in both study towns with no significant differences in proportions of households discarding all six food types. One of the key results is that the average self-reported and weighed food waste generated per capita per annum for the two towns was 23.40±47.20 and 202.60±128.30 kg/capita/year, respectively as compared to the estimated 6-11 kg per annum in sub-Saharan Africa and South and Southeast Asia. Between the towns, Cradock generated more food waste (5.05±2.68 kg) than those in Middleburg (3.84±2.59 kg) in the previous 48 hours. It was also evident that each household and each person in Cradock generated more food waste at breakfast and the least at lunch, while in Middelburg the highest average amount of food waste generated was observed at supper and the least at lunch. The results indicate that household size and employment status were negatively correlated to food waste generation, while wealth status and gender were positively correlated to food waste generation. Majority of households (74% in Cradock and 73% in Middelburg) had no household food waste minimisation strategies implemented. The most cited strategies in place were cooking less frequently, cooking small portions and chopping and freezing vegetables as an anti-food waste strategy. Worth noting is that the small proportion of households with strategies in place are faced with a challenge of some household members showing unwillingness to effectively implement the strategies. The results also reveal that children wasted more food than adults, particularly girls. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2022
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- Date Issued: 2022-04
Effects of elevated temperature, rainfall and soil nutrients on acacia mearnsii invasion
- Authors: Kharivha, Tshililo
- Date: 2021-10
- Subjects: Acacia mearnsii , Acacia mearnsii Effect of high temperatures on South Africa , Acacia mearnsii Climatic factors South Africa , Plant invasions South Africa , Invasive plants , Climatic changes South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/189997 , vital:44954
- Description: Climate change is associated with the risk of plant invasion hence a better understanding of the effects of elevated temperature, precipitation and soil nutrients on dominant invasive plants is needed for effective ecological planning. This study was set out to: (i) examine how elevated temperature (±2°C increase), (ii) high (above local average) and low (below local average) precipitation, (iii) elevated soil nutrient content (increase in soil N), and (iv) a combination of the above manipulations affects germination and growth of Acacia mearnsii, a dominant invasive plant in South Africa. The study further evaluated how the above-mentioned treatments affect soil chemical properties following A. mearnsii germination and growth. The above-mentioned specific objectives were tested under manipulated greenhouse conditions over six experimental months. The results indicated that the above-mentioned climate change scenarios have the potential to facilitate germination and growth of the invasive species A. mearnsii, and this is likely to proliferate its invasion in future. Results showed that seed germination was significantly high under all climate change manipulation treatments (˃50%) with highest seed germination recorded under high rainfall treatment (64%). Plant height was significantly higher under high temperature and high rainfall treatments throughout all the experimental months, though it was lowest under high nitrogen and combined treatment with high rainfall. The numbers of branches were high under higher temperature and low rainfall treatments than under high rainfall, high nitrogen and both combined treatments of low and high rainfall. Relative to the control, plants grown under climate change scenarios increased their root lengths, but this varied across different treatments. Total dry biomass was relatively high under high temperature treatment (0,7 g). Lower plant dry biomass was observed under low and high rainfall treatments (0,4 g), high nitrogen and combined treatments with both low and high rainfall treatments (0,1 g). Concerning the effects of climate change scenarios on soil chemical properties, soil pH levels were significantly higher after A. mearnsii germination and growth than before the experiment was setup. Soil resistivity was significantly higher in climate change treatments receiving nitrogen and combined treatments of low rainfall than other treatments and the soils before experiment. Soil total P was significantly higher in all the climate change treatments after A. mearnsii germination experiment than the before experiment soils. Soils receiving high temperature, high nitrogen, and combined treatment of low rainfall had significantly higher soil total N than other treatments and the before experiment soils. Soil total C was significantly higher in soils receiving high temperature, high nitrogen, and combined treatment of low rainfall after A. mearnsii germination than other treatments and before experiment soils. The findings suggest that future climate change scenarios of increased temperature and rainfall with soil nutrients could considerably enhance growth and germination success of the invasive plant A. mearnsii. Similarly, climate change scenarios could enhance some soil nutrient properties, which in turn, is likely to give the invasive plant A. mearnsii a germination and growth advantage. These results are the first in South Africa to show that future climate changes have the potential to facilitate A. mearnsii germination and growth, making it more invasive. The findings have implications for invasive plants management, especially action for managing the plant through clearing of the plant in sensitive ecosystems (e.g. riparian systems). , Thesis (MSc) -- Faculty of Science, Environmental Science, 2021
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- Date Issued: 2021-10