Restoration of degraded subtropical thickets in the Baviaanskloof Megareserve, South Africa: the role of carbon stocks and Portulacaria afra survivorship
- Authors: Powell, Michael John
- Date: 2009
- Subjects: Portulacaria afra -- South Africa -- Eastern Cape , Portulacaceae -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Plant conservation -- South Africa -- Eastern Cape , Shrubs -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape , Baviaanskloof (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4764 , http://hdl.handle.net/10962/d1007164 , Portulacaria afra -- South Africa -- Eastern Cape , Portulacaceae -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Plant conservation -- South Africa -- Eastern Cape , Shrubs -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape , Baviaanskloof (South Africa)
- Description: The semi-arid forms of subtropical thicket in the Eastern and Western Cape have been heavily degraded through unsustainable pastoralism over the last century or more. The degraded areas exhibit a significant loss of above-ground and belowground carbon stocks, and consequently provide an opportunity for restoration through the formal and informal carbon markets. A prerequisite for the attainment of carbon credits is to ensure sound carbon stock baselines prior to effecting restoration. I report on the carbon stocks (including sub-pools) for a number of intact subtropical thicket types, as well as the differentials between the intact and degraded states (including the sub-pools). Total carbon stocks (TCS in t C ha⁻¹) for intact vegetation (to a soil depth 0–25 cm), ranged from 87.73±6.51 to 70.64±17.24. For degraded vegetation (including old lands), TCS (t C ha⁻¹) ranged from 34.05±3.61 to 21.03±2.70. For all vegetation types, the differentials in TCS along the degradation gradient (0–25 cm) are highly significant and strengthen the possibility for carbon credit financing to catalyse the restoration of the degraded semi-arid subtropical thickets. This study has shown a mean loss of 57.23 t C ha⁻¹ in Baviaanskloof spekboom thickets, when measured to a soil depth of 25 cm. Portulacaria afra is a key species within the semi-arid subtropical thickets, being a canopy dominant and a driver of soil nutrient status, but has been largely lost from the degraded landscapes. Degraded semi-arid subtropical thicket vegetation lacks regeneration via seedling recruitment; restoration therefore requires the manual replanting of P. afra using cut truncheons. Survivorship trials were undertaken infield in 2005 to establish restoration protocols for P. afra, with survivorship being recorded in 2006 and 2008. Overall survivorship for all treatments was found to be 43.2±2.8% in 2006, dropping to 35.8±2.7% in 2008. Planting posture (flat or upright) showed the most significant results of all the factors tested in 2006 and 2008. Micro-damming also influenced survivorship in that micro-damming was associated with marginally higher survivorship (47.4 ±2.0% with damming vs. 39.1±1.5% without damming in 2006, and 39.3±1.9% vs. 32.3±1.5% in 2008). Higher planting density only showed a significant positive impact on survivorship in 2008. Neither stem diameter nor clumping significantly affected degree of survival. A key finding in the study has been the non-static nature of P. afra truncheon survivorship, even after being well established (three years since planting). The results from the study will guide the restoration protocols for the restoration of degraded subtropical thickets, where P. afra requires replanting.
- Full Text:
- Date Issued: 2009
- Authors: Powell, Michael John
- Date: 2009
- Subjects: Portulacaria afra -- South Africa -- Eastern Cape , Portulacaceae -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Plant conservation -- South Africa -- Eastern Cape , Shrubs -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape , Baviaanskloof (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4764 , http://hdl.handle.net/10962/d1007164 , Portulacaria afra -- South Africa -- Eastern Cape , Portulacaceae -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Plant conservation -- South Africa -- Eastern Cape , Shrubs -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape , Baviaanskloof (South Africa)
- Description: The semi-arid forms of subtropical thicket in the Eastern and Western Cape have been heavily degraded through unsustainable pastoralism over the last century or more. The degraded areas exhibit a significant loss of above-ground and belowground carbon stocks, and consequently provide an opportunity for restoration through the formal and informal carbon markets. A prerequisite for the attainment of carbon credits is to ensure sound carbon stock baselines prior to effecting restoration. I report on the carbon stocks (including sub-pools) for a number of intact subtropical thicket types, as well as the differentials between the intact and degraded states (including the sub-pools). Total carbon stocks (TCS in t C ha⁻¹) for intact vegetation (to a soil depth 0–25 cm), ranged from 87.73±6.51 to 70.64±17.24. For degraded vegetation (including old lands), TCS (t C ha⁻¹) ranged from 34.05±3.61 to 21.03±2.70. For all vegetation types, the differentials in TCS along the degradation gradient (0–25 cm) are highly significant and strengthen the possibility for carbon credit financing to catalyse the restoration of the degraded semi-arid subtropical thickets. This study has shown a mean loss of 57.23 t C ha⁻¹ in Baviaanskloof spekboom thickets, when measured to a soil depth of 25 cm. Portulacaria afra is a key species within the semi-arid subtropical thickets, being a canopy dominant and a driver of soil nutrient status, but has been largely lost from the degraded landscapes. Degraded semi-arid subtropical thicket vegetation lacks regeneration via seedling recruitment; restoration therefore requires the manual replanting of P. afra using cut truncheons. Survivorship trials were undertaken infield in 2005 to establish restoration protocols for P. afra, with survivorship being recorded in 2006 and 2008. Overall survivorship for all treatments was found to be 43.2±2.8% in 2006, dropping to 35.8±2.7% in 2008. Planting posture (flat or upright) showed the most significant results of all the factors tested in 2006 and 2008. Micro-damming also influenced survivorship in that micro-damming was associated with marginally higher survivorship (47.4 ±2.0% with damming vs. 39.1±1.5% without damming in 2006, and 39.3±1.9% vs. 32.3±1.5% in 2008). Higher planting density only showed a significant positive impact on survivorship in 2008. Neither stem diameter nor clumping significantly affected degree of survival. A key finding in the study has been the non-static nature of P. afra truncheon survivorship, even after being well established (three years since planting). The results from the study will guide the restoration protocols for the restoration of degraded subtropical thickets, where P. afra requires replanting.
- Full Text:
- Date Issued: 2009
Vegetation and soil characteristics around water points under three land management systems in semi-arid rangelands of the Eastern Cape, South Africa
- Authors: Simanga, Siyabulela
- Date: 2013
- Subjects: Livestock -- Effect of water quality on -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Range ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Pasture Science)
- Identifier: vital:11584 , http://hdl.handle.net/10353/d1015795 , Livestock -- Effect of water quality on -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Range ecology -- South Africa -- Eastern Cape
- Description: This study investigated the vegetation and soil characteristics in relation to distance from water points under different land management systems in semi-arid rangelands of South Africa. Six study sites, two each from communal grazing, commercial farming and game reserves were selected. Two watering points were selected in each study site. Two 500 m transects were laid from the selected watering points. Each transect was divided into sub-transects at 25 m, 50m, 100m, 200m, 300m and 500m from water points. A 100 m2 plot was marked in each sub-transect to record grass biomas, species composition, structure and distribution of woody vegetation and physical and chemical soil properties. Data were collected for two seasons 2012/13 (winter and summer). Thirty and 41 grass and woody species respectively were identified in all study areas. The most common and dominating grass species include Cynodon dactylon, Digitaria eriantha, Eragrostis obtusa, Setaria sphacelata and Sporobolus fimbriatus. Cynodon dactylon and S. sphacelata occurred more abundantly (p < 0.05) in the game reserves than in the other land management catergories. All the grass species had similar (p > 0.05) abundance along distance gradient from water points. Grass dry matter (GDM) showed significant differences (p < 0.05) between and within land management systems. However, GDM was not significantly affected by season, location of water point within each farm or reserve and distance along water points. Acacia karoo, Coddia rudis and Ehretia rigida were the most dominant woody species. Tree equivalent (TE) density of all encroaching woody plants combined was significantly (p < 0.05) higher on the communal area (1732 TE ha-1) than the commercial ranches (1136 TE ha-1) and game reserves (857 TE ha-1), but with no marked variations along distance from water points under all the land management systems. The electric conductivity (EC) was significantly (P < 0.01) higher in game reserves than in communal grazing areas and ranches. Soil organic matter percentage showed greatest and lowest values in the game reserves and commercial respectively. Soil pH and bulk density did not vary but soil organic matter (SOM), EC, bulk density and soil compaction were significant different with no increasing or decreasing trends. Soil properties were affected by herbivore pressure and trampling around water points with inconsistence magnitude and direction. In conclusion, grass species composition and GDM did not respond to distance from water points because either grazing gradient was absent or the length of transects was not enough to explain the absence or presence of gradients. High proportion of A. karoo and high densities of seedlings and saplings would seem as very good indicators of the woody vegetation changes in the different land management systems and distance from water points. The soil quality indicators around the water-points showed that livestock and game affected soil parameters.
- Full Text:
- Date Issued: 2013
- Authors: Simanga, Siyabulela
- Date: 2013
- Subjects: Livestock -- Effect of water quality on -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Range ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Pasture Science)
- Identifier: vital:11584 , http://hdl.handle.net/10353/d1015795 , Livestock -- Effect of water quality on -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Range ecology -- South Africa -- Eastern Cape
- Description: This study investigated the vegetation and soil characteristics in relation to distance from water points under different land management systems in semi-arid rangelands of South Africa. Six study sites, two each from communal grazing, commercial farming and game reserves were selected. Two watering points were selected in each study site. Two 500 m transects were laid from the selected watering points. Each transect was divided into sub-transects at 25 m, 50m, 100m, 200m, 300m and 500m from water points. A 100 m2 plot was marked in each sub-transect to record grass biomas, species composition, structure and distribution of woody vegetation and physical and chemical soil properties. Data were collected for two seasons 2012/13 (winter and summer). Thirty and 41 grass and woody species respectively were identified in all study areas. The most common and dominating grass species include Cynodon dactylon, Digitaria eriantha, Eragrostis obtusa, Setaria sphacelata and Sporobolus fimbriatus. Cynodon dactylon and S. sphacelata occurred more abundantly (p < 0.05) in the game reserves than in the other land management catergories. All the grass species had similar (p > 0.05) abundance along distance gradient from water points. Grass dry matter (GDM) showed significant differences (p < 0.05) between and within land management systems. However, GDM was not significantly affected by season, location of water point within each farm or reserve and distance along water points. Acacia karoo, Coddia rudis and Ehretia rigida were the most dominant woody species. Tree equivalent (TE) density of all encroaching woody plants combined was significantly (p < 0.05) higher on the communal area (1732 TE ha-1) than the commercial ranches (1136 TE ha-1) and game reserves (857 TE ha-1), but with no marked variations along distance from water points under all the land management systems. The electric conductivity (EC) was significantly (P < 0.01) higher in game reserves than in communal grazing areas and ranches. Soil organic matter percentage showed greatest and lowest values in the game reserves and commercial respectively. Soil pH and bulk density did not vary but soil organic matter (SOM), EC, bulk density and soil compaction were significant different with no increasing or decreasing trends. Soil properties were affected by herbivore pressure and trampling around water points with inconsistence magnitude and direction. In conclusion, grass species composition and GDM did not respond to distance from water points because either grazing gradient was absent or the length of transects was not enough to explain the absence or presence of gradients. High proportion of A. karoo and high densities of seedlings and saplings would seem as very good indicators of the woody vegetation changes in the different land management systems and distance from water points. The soil quality indicators around the water-points showed that livestock and game affected soil parameters.
- Full Text:
- Date Issued: 2013
Biodiversity of Salmonella strains isolated from selected water sources and wastewater discharge points in the Easern Cape Province of South Africa
- Authors: Mafu, Nwabisa Charity
- Date: 2008
- Subjects: Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11248 , http://hdl.handle.net/10353/74 , Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Description: In this study, the diversity of forty Salmonella isolates from selected drinking water and wastewater sources in the Eastern Cape Province of South Africa was assessed using parameters such as protein and lipopolysaccharide profile analysis, DNA fingerprinting and antibiotic susceptibility profile as test indices. Wastewater samples from Amalinda, Shornville and Fort Hare wastewater plants, and water samples from Gogogo and Tyume rivers were collected on ice and transported to the laboratory of the department of Microbiology and Biochemistry, University of Fort Hare for processing. The DNA dendograms of Salmonella and the applied UPGMA revealed 4 similarity groups of the strains. Most of the strains recovered from Amalinda, Shornville, Fort Hare wastewater plants, Gogogo and Tyume rivers show a high percentage of genetic similarity. On the other hand, protein dendograms of Salmonella isolates revealed 2 similarity groups which varied widely. Also, the lipopolysaccharide dendograms revealed three similarity groups with the first similarity groups showing a very high relatedness between strains from different water sources. The second similarity group included 16 strains which formed a rather homogenous group, and the third similarity group formed a distinct group. Of the seven antibiotics and sulfonamides tested against the Salmonella species, five namely, neomycin, chloramphenicol, kanamycin, streptomycin and cotrimoxazole were significantly inhibitory, while the bacteria showed considerable resistance to doxycycline and sulphamethoxazole. Our results based on restriction digestion, SDS/PAGE and dendogram construction show that there is a high similarity between the forty Salmonella strains studied, and that these methods are valuable tools for evaluating the relatedness ofSalmonella species. Our observations have proffered a veritable reference point on the diversity of Salmonella strains in the studied area.
- Full Text:
- Date Issued: 2008
- Authors: Mafu, Nwabisa Charity
- Date: 2008
- Subjects: Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11248 , http://hdl.handle.net/10353/74 , Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Description: In this study, the diversity of forty Salmonella isolates from selected drinking water and wastewater sources in the Eastern Cape Province of South Africa was assessed using parameters such as protein and lipopolysaccharide profile analysis, DNA fingerprinting and antibiotic susceptibility profile as test indices. Wastewater samples from Amalinda, Shornville and Fort Hare wastewater plants, and water samples from Gogogo and Tyume rivers were collected on ice and transported to the laboratory of the department of Microbiology and Biochemistry, University of Fort Hare for processing. The DNA dendograms of Salmonella and the applied UPGMA revealed 4 similarity groups of the strains. Most of the strains recovered from Amalinda, Shornville, Fort Hare wastewater plants, Gogogo and Tyume rivers show a high percentage of genetic similarity. On the other hand, protein dendograms of Salmonella isolates revealed 2 similarity groups which varied widely. Also, the lipopolysaccharide dendograms revealed three similarity groups with the first similarity groups showing a very high relatedness between strains from different water sources. The second similarity group included 16 strains which formed a rather homogenous group, and the third similarity group formed a distinct group. Of the seven antibiotics and sulfonamides tested against the Salmonella species, five namely, neomycin, chloramphenicol, kanamycin, streptomycin and cotrimoxazole were significantly inhibitory, while the bacteria showed considerable resistance to doxycycline and sulphamethoxazole. Our results based on restriction digestion, SDS/PAGE and dendogram construction show that there is a high similarity between the forty Salmonella strains studied, and that these methods are valuable tools for evaluating the relatedness ofSalmonella species. Our observations have proffered a veritable reference point on the diversity of Salmonella strains in the studied area.
- Full Text:
- Date Issued: 2008
Quantifying degraded subtropical thicket structure and composition: a multi-scale approach in the Eastern Cape, South Africa
- Authors: Lunderstedt, Kyra Elizabeth
- Date: 2017
- Subjects: Portulacaceae -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Savanna ecology -- South Africa -- Eastern Cape , Shrubs -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5281 , vital:20804
- Description: The loss in canopy cover from over-browsing severely degrades the ecological integrity of spekboom-dominated thicket in the Eastern Cape. A homogenisation of species across the landscape and high heterogeneity at fine scales has been reported with little evidence of recovery. As an interlinked consequence, the loss in important biological structures and composition impacts greatly on soil resources and therefore function. This thesis provides a baseline of degraded thicket abiotic and biotic structure and composition over both spatial and temporal scales within the Greater Addo Elephant National Park (GAENP), including Darlington, Kabouga and Addo Main and within the Baviaanskloof. The study aimed to find correlates of species composition within sites and assess changes in composition with degradation and recovery times. Across the GAENP, landscape degradation was most evident in post-1960 aerial imagery. The duration since sampled sites have been incorporated into the GAENP did not influence species composition, however the period of degradation and severity, did. Across the landscape, communities were strongly associated with each of the four sites and separated predominantly by rainfall, gravel and altitude. A total of 345 plant species were identified across the landscape and despite degradation, each site was characterised into three to five communities each, barring Baviaanskloof which had no significantly different communities. Across the landscape, matrix composition comprised predominantly of Pentzia incana, Drosanthemum hispidum, Galenia pubescens and Cynodon species. Woody cover within patches included smaller Grewia robusta, Rhigozum obovatum and Vachellia karroo and the larger Pappea capensis and Euclea undulata. The succulent shrub Euphorbia caerulescens in Darlington and succulent tree Aloe ferox in Baviaanskloof occurred abundantly as a consequence of degradation. Species richness was significantly correlated to patch size in all sites, but Kabouga had the greatest richness and probability of a suite of species occurring within a patch. Higher woody and succulent cover in Kabouga was therefore associated with higher soil C, root percentage and bulk density. Other sites were higher in Ca, Na, K and P. The method of degradation scoring was not sufficiently accurate and it is recommended that indicator species within the matrix should be used instead of growth forms. The findings of this thesis are conceptualised within a double-cusped catastrophe model and recommendations for restoration are provided.
- Full Text:
- Date Issued: 2017
- Authors: Lunderstedt, Kyra Elizabeth
- Date: 2017
- Subjects: Portulacaceae -- South Africa -- Eastern Cape , Biodiversity conservation -- South Africa -- Eastern Cape , Savanna ecology -- South Africa -- Eastern Cape , Shrubs -- South Africa -- Eastern Cape , Succulent plants -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5281 , vital:20804
- Description: The loss in canopy cover from over-browsing severely degrades the ecological integrity of spekboom-dominated thicket in the Eastern Cape. A homogenisation of species across the landscape and high heterogeneity at fine scales has been reported with little evidence of recovery. As an interlinked consequence, the loss in important biological structures and composition impacts greatly on soil resources and therefore function. This thesis provides a baseline of degraded thicket abiotic and biotic structure and composition over both spatial and temporal scales within the Greater Addo Elephant National Park (GAENP), including Darlington, Kabouga and Addo Main and within the Baviaanskloof. The study aimed to find correlates of species composition within sites and assess changes in composition with degradation and recovery times. Across the GAENP, landscape degradation was most evident in post-1960 aerial imagery. The duration since sampled sites have been incorporated into the GAENP did not influence species composition, however the period of degradation and severity, did. Across the landscape, communities were strongly associated with each of the four sites and separated predominantly by rainfall, gravel and altitude. A total of 345 plant species were identified across the landscape and despite degradation, each site was characterised into three to five communities each, barring Baviaanskloof which had no significantly different communities. Across the landscape, matrix composition comprised predominantly of Pentzia incana, Drosanthemum hispidum, Galenia pubescens and Cynodon species. Woody cover within patches included smaller Grewia robusta, Rhigozum obovatum and Vachellia karroo and the larger Pappea capensis and Euclea undulata. The succulent shrub Euphorbia caerulescens in Darlington and succulent tree Aloe ferox in Baviaanskloof occurred abundantly as a consequence of degradation. Species richness was significantly correlated to patch size in all sites, but Kabouga had the greatest richness and probability of a suite of species occurring within a patch. Higher woody and succulent cover in Kabouga was therefore associated with higher soil C, root percentage and bulk density. Other sites were higher in Ca, Na, K and P. The method of degradation scoring was not sufficiently accurate and it is recommended that indicator species within the matrix should be used instead of growth forms. The findings of this thesis are conceptualised within a double-cusped catastrophe model and recommendations for restoration are provided.
- Full Text:
- Date Issued: 2017
- «
- ‹
- 1
- ›
- »