Drivers of vegetation change in the eastern Karoo.

Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.The Nama-Karoo Biome occupies much of the western central region of South Africa and transitions into the Grassland Biome along its eastern boundary along a gradual ecotone. The area is characterised by hot summers and long, frosty winters, relatively low rainfall, peaking in mid- to late-summer, with high inter-annual variability, and botanically by a co-existence of grasses and dwarf shrubs, with grass abundance positively related to average annual rainfall that increases from west to east. Biome shifts in response to changes in rainfall pattern and grazing have been suggested but never directly examined. Major drivers of botanical composition are rainfall and grazing by livestock. Fire is rare, occurring sporadically if high rainfall allows for good grass growth. This thesis focused on understanding the influence of rainfall, grazing, low temperatures, and fire on botanical composition at Grootfontein, a site in the ecotone between the Nama-Karoo and Grassland Biomes that is home to grazing trials up to 85 years old. The following specific questions were addressed: Question 1: Over the long term, has Grootfontein shown patterns of rainfall cyclicity or experienced directional change, and how might these have influenced composition and productivity? Using data from 1888 to 2012, cyclicity in rainfall was evident for periods of approximately 20 and 60 years. Rainfall has also consistently increased since the mid-1970s, and this increase corresponds with a general pattern of increased grassiness in the eastern Karoo. Question 2: How do rainfall and grazing, alone and in interaction, influence vegetation composition in the eastern Karoo? Compositional data from the 1960s and 2010s from various treatments at two sites at Grootfontein (Camp 6 and Seligman grazing trials) show a shift from dwarf-shrub- to grass-dominated vegetation, consistent with the increased rainfall over that time. An influence of grazing, both present and historical, was evident but secondary to the effect of rainfall. In some cases, there has been a shift to grassland. Data from the Camp 6 and Seligman grazing trials from the 1940s to the 1960s further indicate a combined influence of season of grazing and of rainfall. High-intensity summer-only grazing by livestock largely extirpates grasses and allows shrubs to thrive, while summer grazing in the form of rotational grazing or continuous grazing allow for a balance of grasses and dwarf-shrubs. Severe declines in both grasses and shrubs occurred apparently in response to drought, though the exact conditions required to cause such mortality remain unclear. Plant cover data from 2008 to 2015 from the Boesmanskop grazing trial showed that consecutive years of exceptionally high rainfall increased plant cover to nearly 100%, and increased the abundance of grasses. Competitive exclusion of dwarf-shrubs by grasses was not evident. Question 3: What have been the trends in minimum temperatures, frost, and potential growth season at Grootfontein, how might these have influenced botanical composition and productivity, and is there evidence of increasing temperatures consistent with global warming? This is addressed using minimum-temperature data from 1916 to 2014. Minimum temperatures were lower than are usually reported. Variability in minimum temperatures was high, including a cooling from the 1910s to the 1950s and a warming from the 1950s to the 2010s. The length of the growing season (last frost to first frost of the subsequent season) varied considerably, and may have the potential to influence botanical composition. Question 4: What is the influence of fire in Karoo vegetation? Based on the effects of a single fire on Grootfontein, fire killed some species while most species resprouted. Grasses appeared unaffected in terms of survival, several species of dwarf shrub (notably Eriocephalus ericoides and Ruschia intricata) were killed, and will need to re-establish by seed (termed nonsprouters), while most dwarf shrub species resprouted. This resprouter/ nonsprouter dichotomy was found to be evident at a range of other fire sites in the Karoo. Heavy grazing appeared to strongly impede the recovery of burnt veld, maintaining it as a sparse grassland dominated by annual species and occasional unpalatable shrubs. Should the grassiness of the Karoo continue to increase, then fire may become more frequent thereby maintaining a grassland state. The findings allow for greater understanding of interactions among rainfall, grazing, and fire in eastern Karoo ecosystems, and these are discussed in the context of an existing state-andtransition model of eastern Karoo vegetation dynamics. The importance of long-term rainfall trends, rather than short-term variability, are highlighted. Long-term increases in rainfall will likely induce a biome shift to grassland, concomitant with a drastic reduction in dwarf-shrubs. This will likely alter both long-term carrying capacity for livestock and the type of animals that may be optimally stocked. Increased grassiness will result in the increased likelihood of fire, and if post-fire grass fuel loads remain above a critical level, a fire/grass feedback loop may be initiated whereby dwarf-shrubs are largely eliminated owing to their slow rates of growth or re-establishment. Introduction of infrequent fire will likely result in resprouter-dominated vegetation proliferating. It is demonstrated that the resilience of Karoo veld may be higher than previously thought, with severe grazing, droughts, and fire not pushing veld beyond a threshold into a state of denudation. Thus the prospects of conserving Karoo landscapes despite historical management remain high. Some key future research efforts needed to improve our understanding of Karoo ecology include the life-histories of dwarf-shrubs, the conditions of drought and herbivory under which grasses and dwarf-shrubs die, and how and when perennial dwarf-shrubs and grasses regenerate. Based on historical trends, the continued existence of long-term research trials, such as those at Grootfontein, may be under threat and should receive attention

Factors influencing the long-term competitiveness of selected commercial milk producers in east Griqualand, South Africa.

Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.This study presents two separate competitiveness analyses to assess changes in, and factors influencing, the long-term competitiveness of a panel of commercial milk producers in East Griqualand (EG), South Africa. The Unit Cost Ratio (UCR) method was used to measure competitiveness of EG milk producers. It is defined as the ratio of dairy enterprise accounting costs plus an opportunity cost of management at 5% of milk revenue, to total dairy enterprise revenue. The initial UCR analysis was used to partly investigate the impact of dairy market deregulation on the relative competitiveness of EG milk producers over the period 1983 to 2006. The results of this UCR analysis found that the sample of EG milk producers were not competitive based on the net local price, PL, received for milk but were competitive when dairy cattle trading income was included. This suggests that dairy cattle trading income played an important role in enhancing the competitiveness of EG dairy enterprises in the study period. Further UCR analysis revealed that differences in the inherent ability of members of the EG group to manage market deregulation impacted on the relative competitiveness of EG milk producers. The top onethird of the sample of EG milk producers remained relatively competitive from 1983 to 2006 due to higher real milk prices and lower real unit costs than producers in the bottom one-third category. Differences in relative competitiveness between the top and bottom one-third categories of producers were statistically significant. Based on the findings of the UCR analysis, a Ridge regression analysis was then used to investigate other factors influencing the long-term competitiveness of selected milk producers from EG using unbalanced panel data for the period 1990 – 2006. Results of the regression analysis showed that dairy herd size, the level of farm debt, annual production per cow, technology and policy changes over time, and the ratio of trading income to total milk income influence the long-term competitiveness of these milk producers. To enhance their competitiveness in a deregulated dairy market, relatively small and profitable EG milk producers should consider increasing herd sizes as the importance of herd size in explaining competitiveness suggests that size economies exist. All EG milk producers should consider utilising more pasture and other forages to lower feed costs and select dairy cattle of superior genetic merit to improve milk yields

Patch grazing at Kroomie.

Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003.The patch structure of the grass sward at Kroomie (26°25'38"E 33°48'30"S) in a semi-arid savanna in the Eastern Cape, South Africa, was investigated. The study was conducted on long term grazing trials on five treatments varying in stocking rate (SR; recommended (low) and 1.5 x recommended (high), grazing system (continuous and rotational), and animal type (cattle and sheep). The treatments studied were CR (cattle, rotational stocking, low SR), CC (cattle, continuous stocking, low SR), CH (cattle, rotational stocking, high SR), SC (sheep, continuous stocking, low SR), and SR (sheep, rotational stocking, low SR). Rainfall during the two years of the study (1997/98 and 1998/99) was slightly below the mean average rainfall of the area (66 and 84% of the mean of 519 mm, respectively). Analysis of sward height data using Maximum Likelihood Estimation reflected a bimodal height structure in all treatments. Due to a high overlap of the two distributions in some cases, however, the height at which to separate patches (short grass) from non-patches (tall grass) could not be determined. Canonical Correspondence Analysis (CCA) was used to relate species composition to sward height. It emerged that there are two distinct grass communities at Kroomie, and these are associated with sward height (i.e. patches and non-patches). The interface (in cm) between these two communities, as determined using Two Way Indicator Species Analysis (TWINS PAN) was 6 cm, and this value was subsequently used to discriminate between patches and non-patches. Sward structure was affected by treatments. Animals (cattle and sheep) stocked rotationally at low SR's grazed less than a third of the total area, and this grazing was concentrated primarily in small patches (< 6 m; length is used as a linear indicator of patch size). Animals stocked continuously at low SR's grazed approximately half the area, in small and large (up to 40 m) patches. Animals in the CH treatment grazed approximately two-thirds of the area, in both small and large patches. There was an inverse relation between the size of patches and the size of non-patches, as expected. Nine common grass species were related to sward height. Digiteria eriantha, Eragrostis racemosa, Eustachys paspaloides, and Microchloa caffra were associated with short swards, while Cymbopogon pluronodis, Eragrostis chloromelas, and Sporobolus fimbriatus were associated with tall swards. Themeda triandra (themeda), the most abundant grass at Kroomie, was principally associated with tall swards, but was present at all sward heights. Applying CCA demonstrated a considerable difference between the species composition of patches and of non-patches. There was also a difference in composition between treatments, although these were not as pronounced. Patches reflected a higher species diversity than non-patches. There was a significant (P<0.05) effect of treatment, and of an interaction of treatment by sward structure (i.e. patches and non-patches), on the density of themeda plants. The density of themeda plants was positively correlated with patch size, which suggested that themeda plants that have been grazed may suffer fatal competition from ungrazed neighbours. Anecdotal evidence suggested that patches are stable over the medium term, and that non-patches that are grazed during a drought return to a non-patch structure after rainfall. There was no evidence to support the contention that rotational stocking reduced patch-selective grazing, nor that the species composition of rotationally stocked treatments was better than continuously stocked treatments

Deep eutectic solvents for solid pesticide dosage forms

Deep eutectic solvents aid the formulation of solid pesticide dosage forms for water-insoluble actives. This was demonstrated by encapsulating Amitraz powder in a low-melting matrix based on the eutectic mixture of urea (32 wt%) and 1,3-dimethylurea. Dissolution in water of melt-cast discs, containing 20 wt% active, led to the rapid release of Amitraz in a finely dispersed form. The order of magnitude reduction in particle size, after dissolution, is ascribed to the solubilization of Amitraz in the hot deep eutectic solvent and its subsequent precipitation as a separate phase on crystallization of the matrix.The Institute of Applied Materials, University of Pretoriahttp://www.nature.com/srepam2021Chemical Engineerin

The prevalence of probable depression and probable anxiety, and associations with adverse childhood experiences and socio-demographics: a national survey in South Africa

Objective and methods: Mental health problems among adults are a growing public health concern, and middle-income countries such as South Africa are disproportionally affected. Using a large scale nationally representative weighted survey, we assessed the prevalence of probable depression, probable anxiety, and adverse childhood experiences (ACEs), and explored associations between probable depression, probable anxiety, ACEs, socio-economic status, and demographic characteristics. Results: Nationally, 25.7, 17.8, and 23.6% of respondents, respectively, reported scores of ≥10 on the Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7), indicating probable depression or probable anxiety, and an ACE score of ≥4 (high exposure). Overall probable depression prevalence across South Africa varied from 14.7 to 38.8%. Both probable depression and probable anxiety were more frequently reported among adults who were: retired and older (>65 years of age), and widowed, divorced, or separated; living in metropolitan areas; and only had primary school education. In a multivariable adjusted logistic regression, the likelihood of reporting probable depression or probable anxiety was also found to increase with each standard deviation increase in the ACE score (p < 0.001), independent of other socio-demographic determinants. Conclusion: The prevalence of probable depression among respondents in South Africa varies significantly across the nine provinces. Furthermore, higher ACE score and several socio-demographic determinants were associated with a higher likelihood of probable depression and probable anxiety. Adult mental health services are urgently needed to identify groups of the population vulnerable to mental health problems for better targeting of interventions. Given the range of probable depression prevalence across the country, provincial level plans and resources should also reflect the burden of mental health problems in that province

A successful lifestyle intervention model replicated in diverse clinical settings

Lifestyle interventions can treat metabolic syndrome and prevent type 2 diabetes mellitus, but they remain underutilised in routine practice. In 2010, an LI model was created in a rural primary care practice and spread with few resources to four other rural practices. A retrospective chart review evaluated changes in health indicators in two practice environments by following 372 participants, mainly women (mean age 52 years). Participants had a mean body mass index of 37 kg/m2at baseline and lost an average of 12% of their initial body weight as a result of the intervention. Among participants at the first intervention site for whom cardiometabolic data were available, the prevalence of metabolic syndrome decreased from 58% at baseline to 19% at follow-up. Taken as a whole, our experience suggests that LIs are feasible and deliver meaningful results in routine primary care practice.

Livestock grazing and biodiversity : effects on CO2 exchange in semi-arid Karoo ecosystems, South Africa

DATA AVAILABILITY : Data used in this study can be obtained upon request and will be made available through the FLUXNET database.Livestock use in semi-arid South African ecosystems has not been extensively studied in relation to the Net Ecosystem Exchange (NEE) of carbon dioxide (CO2). We present four years of measurements from twinned eddy-covariance towers in Nama-Karoo, South Africa, to investigate the carbon fluxes and the impact of grazing intensity on NEE. The design contrasted NEE at a long-term site grazed at recommended levels (LG) with a long-term heavily grazed (EG) site that had been rested for 10 years, and was monitored for two years after which intensive grazing was reintroduced for this experiment. This allowed for the quantification of long-term NEE trends on “recovering” vegetations (years I, II) and short-term responses to an intensified land use (years III, IV). The results showed that the net release of CO2 was slightly higher at LG than on “recovering” vegetation at the EG site, where near-neutral exchange was observed during years I and II. However, after grazing was reintroduced to the EG site, differences between sites was reduced but not eliminated. These findings suggest that there is a somewhat higher carbon sequestration potential at the resting EG site than at the LG site, apparently associated with the dominance of unpalatable drought-tolerant grass species and local elimination of many palatable shrubs. Reduction of this sink potential by reintroduction of high-intensity grazing indicates the sensitivity of C-sequestration in this “recovering” system to heavy grazing, but underlines continued resilience of NEE under far heavier grazing than in the LG system. These data suggest notable trade-offs in these ecosystems between carbon storage, biodiversity, and livestock production with rainfall variability being a critical inter-annual driver.This study suggests that long-term resting of previously over-utilized southern African semi-arid vegetation supports enhanced carbon sequestration potential, even if over-utilization has transformed vegetation composition (i.e. has caused degradation through reduced plant species richness). However, this enhanced carbon sequestration potential can be quickly negated by the reintroduction of grazing, even after 10 years of resting. Achievement of carbon sequestration is dependent on average to above-average precipitation and its distribution throughout the year, with sink activity evident mainly after seasonal rains during the warm season.he German Federal Ministry of Education and Research (BMBF), research programs SPACES and SPACES II (Science Partnerships for the Assessment of Complex Earth System Processes in Southern Africa), projects ARS AfricaE and EMSAfrica.https://www.elsevier.com/locate/scitotenvhj2024Geography, Geoinformatics and MeteorologySDG-15:Life on lan

Effect of household and community interventions on the burden of tuberculosis in southern Africa: the ZAMSTAR community-randomised trial.

BACKGROUND: Southern Africa has had an unprecedented increase in the burden of tuberculosis, driven by the HIV epidemic. The Zambia, South Africa Tuberculosis and AIDS Reduction (ZAMSTAR) trial examined two public health interventions that aimed to reduce the burden of tuberculosis by facilitating either rapid sputum diagnosis or integrating tuberculosis and HIV services within the community. METHODS: ZAMSTAR was a community-randomised trial done in Zambia and the Western Cape province of South Africa. Two interventions, community-level enhanced tuberculosis case-finding (ECF) and household level tuberculosis-HIV care, were implemented between Aug 1, 2006, and July 31, 2009, and assessed in a 2×2 factorial design between Jan 9, 2010, and Dec 6, 2010. All communities had a strengthened tuberculosis-HIV programme implemented in participating health-care centres. 24 communities, selected according to population size and tuberculosis notification rate, were randomly allocated to one of four study groups using a randomisation schedule stratified by country and baseline prevalence of tuberculous infection: group 1 strengthened tuberculosis-HIV programme at the clinic alone; group 2, clinic plus ECF; group 3, clinic plus household intervention; and group 4, clinic plus ECF and household interventions. The primary outcome was the prevalence of culture-confirmed pulmonary tuberculosis in adults (≥18 years), defined as Mycobacterium tuberculosis isolated from one respiratory sample, measured 4 years after the start of interventions in a survey of 4000 randomly selected adults in each community in 2010. The secondary outcome was the incidence of tuberculous infection, measured using tuberculin skin testing in a cohort of schoolchildren, a median of 4 years after a baseline survey done before the start of interventions. This trial is registered, number ISRCTN36729271. FINDINGS: Prevalence of tuberculosis was evaluated in 64,463 individuals randomly selected from the 24 communities; 894 individuals had active tuberculosis. Averaging over the 24 communities, the geometric mean of tuberculosis prevalence was 832 per 100,000 population. The adjusted prevalence ratio for the comparison of ECF versus non-ECF intervention groups was 1·09 (95% CI 0·86-1·40) and of household versus non-household intervention groups was 0·82 (0·64-1·04). The incidence of tuberculous infection was measured in a cohort of 8809 children, followed up for a median of 4 years; the adjusted rate ratio for ECF versus non-ECF groups was 1·36 (95% CI 0·59-3·14) and for household versus non-household groups was 0·45 (0·20-1·05). INTERPRETATION: Although neither intervention led to a statistically significant reduction in tuberculosis, two independent indicators of burden provide some evidence of a reduction in tuberculosis among communities receiving the household intervention. By contrast the ECF intervention had no effect on either outcome. FUNDING: Bill & Melinda Gates Foundation

A comparison between the cardio-stress indices of an active and a sedentary population

Die moderne leefwyse bring dikwels mee dat ons die belangrikheid van liggaamlike oefening uit die oog verloor. Ons toenemend passiewe leefwyse het gelei tot ’n aansienlike toename in die voorkoms van lewenstylsiektes soos hipertensie en verskeie vorme van vaskulêre patologie. In hierdie studie word die kardiostres-indekse (KSI’e) van aktiewe en sedentêre individue met mekaar vergelyk ten einde insig te verkry in die uitwerking van die aansienlike veranderinge wat in die gemoderniseerde samelewing plaasgevind het. Die aktiewe populasie het bestaan uit 217 weermagrekrute wat reeds 20 weke van hul basiese weermagopleiding voltooi het. Die (n = 126) lede van die sedentêre populasie is gewerf uit ’n tradisionele tersiêre onderwysinstansie. Die deelnemers uit beide populasies moes drie toetssessies bywoon wat gedurende week 1, week 12 en week 20 gehou is. Hulle het ’n nie-ingrypende ViportTMtoets ondergaan om hul KSI, harttempo en QRS-duur te bepaal. Die resultate het getoon dat alhoewel die basislyn vir KSI, bloeddruk en harttempo aanvanklik hoër was onder die aktiewe populasie, die aanvang van die liggaamsoefeningprogram ten opsigte van hierdie drie faktore ’n geleidelike afname en dus ’n verandering in die rigting, en uiteindelik gesonder marges tot gevolg gehad het. Die KSI het egter nie die normale reikwydte ten opsigte van een van die twee groepe bereik nie, wat daarop gedui het dat alhoewel liggaamlike aktiwiteit fisiologiese stresvlakke verminder, ander sleutelfaktore, te wete leefwyse en stresvlakke, ook in ag geneem moet word. Die studie onderskryf die idee dat ’n toename in liggaamlike aktiwiteit die potensiaal het om ’n individu se vatbaarheid vir kardiovaskulêre siektes te verminder. Die studie ondersoek ook die uitwerking van oefening op die hart deur die gebruik van KSI as ’n meetinstrument.A comparison between the cardio-stress indices of an active and a sedentary population. Our modern lifestyle often results in the importance of physical exercise being overlooked. The increasingly passive way of life has resulted in a notable increase in the prevalence of lifestyle disorders, such as hypertension and some forms of vascular pathology. This study compares the cardio-stress indices (CSIs) of active and sedentary individuals to provide insight into the impact of the significant changes that have taken place in the modernised society. The active population consisted of 217 military recruits who had completed 20 weeks of basic military training. The sedentary population (n = 126) was sourced from a traditional tertiary institution where the focus is on attending lectures. Participants from both populations were required to attend three testing sessions, which were held during Week 1, Week 12 and Week 20. Subjects underwent a non-invasive ViportTM test to measure their CSI, heart rate and QRS duration. The results showed that although baseline readings for CSI, blood pressure (BP) and heart rate (HR) were initially higher among the active population, the commencement of the physical training programme resulted in a steady decline in respect of these three factors to approach healthier margins. However, the CSI for neither population reached the normal range, indicating that although physical activity reduces physiological stress levels, other key factors, namely lifestyle stress levels, must also be taken into account.The study supports the notion that increased physical activity has the potential to reduce the predisposition of an individual to cardiovascular disorders and contributes towards establishing the effect of training on heart health by using CSI as a means of measurementhttp://www.satnt.ac.zaay201

Linking scales and disciplines : an interdisciplinary cross-scale approach to supporting climate-relevant ecosystem management

CITATION: Berger, C. et al. 2019. Linking scales and disciplines : an interdisciplinary cross-scale approach to supporting climate-relevant ecosystem management. Climatic Change, 156:139–150, doi:10.1007/s10584-019-02544-0.The original publication is available at https://www.springer.com/journal/10584Southern Africa is particularly sensitive to climate change, due to both ecological and socioeconomic factors, with rural land users among the most vulnerable groups. The provision of information to support climate-relevant decision-making requires an understanding of the projected impacts of change and complex feedbacks within the local ecosystems, as well as local demands on ecosystem services. In this paper, we address the limitation of current approaches for developing management relevant socio-ecological information on the projected impacts of climate change and human activities.We emphasise the need for linking disciplines and approaches by expounding the methodology followed in our two consecutive projects. These projects combine disciplines and levels of measurements from the leaf level (ecophysiology) to the local landscape level (flux measurements) and from the local household level (socio-economic surveys) to the regional level (remote sensing), feeding into a variety of models at multiple scales. Interdisciplinary, multi-scaled, and integrated socio-ecological approaches, as proposed here, are needed to compliment reductionist and linear, scalespecific approaches. Decision support systems are used to integrate and communicate the data and models to the local decision-makers.https://link.springer.com/article/10.1007/s10584-019-02544-0Publisher's versio