scholarly journals Multi-year CO<sub>2</sub> budgets in South African semi-arid Karoo ecosystems under different grazing intensities

2020 ◽  
Author(s):  
Oksana Rybchak ◽  
Justin du Toit ◽  
Jean-Pierre Delorme ◽  
Jens-Kristian Jüdt ◽  
Kanisios Mukwashi ◽  
...  
Keyword(s):  
Carbon Sequestration ◽  
Carbon Source ◽  
South African ◽  
Water Availability ◽  
Carbon Sink ◽  
Grazing Intensity ◽  
Livestock Grazing ◽  
Carbon Uptake ◽  
The Past ◽  
Semi Arid

Abstract. Climatic and land management factors, such as water availability and grazing intensity, play an important role in seasonal and annual variability of the ecosystem–atmosphere exchange of CO2 in semi-arid ecosystems. However, the semi-arid South African ecosystems have been poorly studied. Four years of measurements (November 2015–October 2019) were collected and analysed from two eddy covariance towers near Middelburg in the Karoo, Eastern Cape, South Africa. We studied the impact of grazing intensity on the CO2 exchange by comparing seasonal and interannual CO2 fluxes for two sites with almost identical climatic conditions but different intensity of current and historical livestock grazing. The first site represents lenient grazing (LG) and the vegetation comprises a diverse balance of dwarf shrubs and grasses, while the second site has been degraded through heavy grazing (HG) in the past but then rested for the past 10 years and mainly consists of unpalatable grasses and ephemeral species. Over the observation period, we found that the LG site was a considerable carbon source (82.11 g C m−2), while the HG site was a slight carbon sink (−36.43 g C m−2). The annual carbon budgets ranged from −90 ± 51 g C m−2 yr−1 to 84 ± 43 g C m−2 yr−1 for the LG site and from −92 ± 66 g C m−2 yr−1 to 59 ± 46 g C m−2 yr−1 for the heavily grazed site over the four years of eddy covariance measurements. The significant variation in carbon sequestration rates between the last two years of measurement was explained by water availability (25 % of the precipitation deficit in 2019 compared to the long-term mean precipitation). This indicates that studied ecosystems can quickly switch from a considerable carbon sink to a considerable carbon source ecosystem. Our study shows that the CO2 dynamics in the Karoo are largely driven by water availability and the current and historical effects of livestock grazing intensity on aboveground biomass (AGB). The higher carbon uptake at the HG site indicates that resting period after overgrazing, together with the transition to unpalatable drought-tolerant grass species, creates conditions that are favourable for carbon sequestration in the Karoo ecosystems, but unproductive as Dorper sheep pasture. Furthermore, we observed a slight decrease in carbon uptake peaks at the HG site in response to resuming continuous grazing (July 2017).

How land management and water availability control ecosystem-atmosphere carbon exchange in the Karoo, South Africa

2020 ◽  
Author(s):  
Oksana Rybchak ◽  
Kanisios Mukwashi ◽  
Justin Du Toit ◽  
Gregor Feig ◽  
Mari Bieri ◽  
...  
Keyword(s):  
Climate Change ◽  
South Africa ◽  
South African ◽  
Land Management ◽  
Water Availability ◽  
Grazing Intensity ◽  
Carbon Fluxes ◽  
Livestock Grazing ◽  
Carbon Uptake ◽  
The Past

&lt;p&gt;South African ecosystems are highly vulnerable to the effects of climate change, such as increasing&amp;#160;temperatures, modifications in rainfall patterns, increasing frequency of extreme weather events and fire, and increased concentration of atmospheric carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;). At the same time, ecosystems are impacted by livestock grazing, cultivation,&amp;#160;fuelwood collection, urbanization and other types of human land use. Climatic and land management factors, such as water availability and grazing intensity, play a dominant role in influencing primary production and carbon fluxes. However, the relative role of those parameters still remains less known in many South African ecosystems. Investigation of the carbon inter-annual variability at dwarf shrub Karoo sites will assist in understanding savanna dynamics and in constraining climate change scenarios as basis for climate adaptation strategies.&amp;#160;&lt;/p&gt;&lt;p&gt;This research is part of the EMSAfrica (Ecosystem Management Support for Climate Change in Southern Africa) project, which aims at producing data and information relevant to land users and land managers such as South African National Parks (SANParks). A particular focus is given on the importance of carbon cycling in degraded vs. intact systems. We investigate the impacts of climate parameters and diverse land management on ecosystem-atmosphere variability of carbon fluxes, latent and sensible energy. Long-term measurements were collected and analyzed from two eddy-covariance towers in the Karoo, Eastern Cape, South Africa. Study areas had almost identical climatic conditions but differ in the intensity of livestock grazing. The first site represents controlled grazing and comprises a diverse balance of dwarf shrubs and grasses, while the second site is degraded through overgrazing in the past (rested for approximately 8 years) and mainly consists of unpalatable grasses and short-lived species. These ecosystems are generally characterized by alternating wet (December to May) and dry seasons (June to November) with the amount and distribution of rain (average 373 mm per year) and soil moisture as the main drivers of carbon fluxes. We observed peak CO&lt;sub&gt;2&lt;/sub&gt; uptake occurring during the wet season (January to April) and a progressive decrease from wet to dry periods being highly controlled by the amount of precipitation. At the end of the observation period (November 2015 &amp;#8211; November 2019), we found that both study sites were considerable carbon sources, but during wet periods 'overgrazed in the past' site had stronger carbon sequestration compared to 'controlled grazing' site. The higher carbon uptake could be an indication that resting of the highly degraded site for a long period may improve carbon uptake in the Karoo ecosystems. Our study shows that CO&lt;sub&gt;2&lt;/sub&gt; dynamics in the Karoo are largely driven by water availability and the effects of grazing intensity on above-ground biomass.&lt;/p&gt;

scholarly journals Predicting the variable ocean carbon sink

2019 ◽  
Vol 5 (4) ◽  
pp. eaav6471 ◽  
Author(s):  
H. Li ◽  
T. Ilyina ◽  
W. A. Müller ◽  
P. Landschützer
Keyword(s):  
Carbon Sink ◽  
System Model ◽  
Carbon Uptake ◽  
Prediction System ◽  
Earth System ◽  
Temperature Variations ◽  
The Past ◽  
Predictive Skill ◽  
Decadal Variations ◽  
Ocean Carbon

Strong decadal variations in the oceanic uptake of carbon dioxide (CO2) observed over the past three decades challenge our ability to predict the strength of the ocean carbon sink. By assimilating atmospheric and oceanic observational data products into an Earth system model–based decadal prediction system, we can reproduce the observed variations of the ocean carbon uptake globally. We find that variations of the ocean CO2 uptake are predictable up to 2 years in advance globally, albeit there is evidence for a higher predictive skill up to 5 years regionally. We further suggest that while temperature variations largely determine shorter-term (<3 years) predictability, nonthermal drivers are responsible for longer-term (>3 years) predictability, especially at high latitudes.

scholarly journals Assessment of Human-Related Driving Forces for Reduced Carbon Uptake Using Neighborhood Analysis and Geographically Weighted Regression: A Case Study in the Grassland of Inner Mongolia, China

2020 ◽  
Vol 10 (21) ◽  
pp. 7787
Author(s):  
Zongyao Sha ◽  
Ruren Li
Keyword(s):  
Carbon Sequestration ◽  
Geographically Weighted Regression ◽  
Inner Mongolia ◽  
Road Network ◽  
Driving Forces ◽  
Grazing Intensity ◽  
Grassland Management ◽  
Weighted Regression ◽  
Carbon Uptake ◽  
Neighborhood Analysis

The ever-rising concentration of atmospheric carbon is viewed as the primary cause for global warming. To discontinue this trend, it is of urgent importance to either cut down human carbon emissions or remove more carbon from the atmosphere. Grassland ecosystems occupy the largest part of the global land area but maintain a relatively low carbon sequestration flux. While numerous studies have confirmed the impacts on grassland vegetation growth from climate changes and human activities, little work has been done to understand the driving forces for a reduced carbon uptake (RCU)—a loss in vegetation carbon sequestration because of inappropriate grassland management. This work focused on assessing RCU in the grassland of Inner Mongolia and understanding the influential patterns of the selected variables (including grazing intensity, road network, population, and vegetation productivity) related to RCU. Neighborhood analysis was proposed to locate optimized grassland management practices from historical data and to map RCU. Ordinary least squares (OLS) and geographically weighted regression (GWR) models were applied to explore the driving forces for RCU. The results indicated that the human-related factors, including stock grazing intensity, population density, and road network were likely to present a spatially varied impact on RCU, which accounted for more than 1/4 of the total carbon sequestration.

scholarly journals Vegetation greenness and land carbon-flux anomalies associated with climate variations: a focus on the year 2015

2017 ◽  
Vol 17 (22) ◽  
pp. 13903-13919 ◽  
Author(s):  
Chao Yue ◽  
Philippe Ciais ◽  
Ana Bastos ◽  
Frederic Chevallier ◽  
Yi Yin ◽  
...  
Keyword(s):  
Carbon Source ◽  
El Niño ◽  
El Nino ◽  
Carbon Sink ◽  
Growing Season ◽  
Satellite Observations ◽  
Carbon Uptake ◽  
Climate Variations ◽  
Strong Transition ◽  
The Tropics

Abstract. Understanding the variations in global land carbon uptake, and their driving mechanisms, is essential if we are to predict future carbon-cycle feedbacks on global environmental changes. Satellite observations of vegetation greenness have shown consistent greening across the globe over the past three decades. Such greening has driven the increasing land carbon sink, especially over the growing season in northern latitudes. On the other hand, interannual variations in land carbon uptake are strongly influenced by El Niño–Southern Oscillation (ENSO) climate variations. Marked reductions in land uptake and strong positive anomalies in the atmospheric CO2 growth rates occur during El Niño events. Here we use the year 2015 as a natural experiment to examine the possible response of land ecosystems to a combination of vegetation greening and an El Niño event. The year 2015 was the greenest year since 2000 according to satellite observations, but a record atmospheric CO2 growth rate also occurred due to a weaker than usual land carbon sink. Two atmospheric inversions indicate that the year 2015 had a higher than usual northern land carbon uptake in boreal spring and summer, consistent with the positive greening anomaly and strong warming. This strong uptake was, however, followed by a larger source of CO2 in the autumn. For the year 2015, enhanced autumn carbon release clearly offset the extra uptake associated with greening during the summer. This finding leads us to speculate that a long-term greening trend may foster more uptakes during the growing season, but no large increase in annual carbon sequestration. For the tropics and Southern Hemisphere, a strong transition towards a large carbon source for the last 3 months of 2015 is discovered, concomitant with El Niño development. This transition of terrestrial tropical CO2 fluxes between two consecutive seasons is the largest ever found in the inversion records. The strong transition to a carbon source in the tropics with the peak of El Niño is consistent with historical observations, but the detailed mechanisms underlying such an extreme transition remain to be elucidated.

scholarly journals Abrupt seasonal transitions in land carbon uptake in 2015

2017 ◽  
Author(s):  
Chao Yue ◽  
Philippe Ciais ◽  
Ana Bastos ◽  
Frederic Chevallier ◽  
Yi Yin ◽  
...  
Keyword(s):  
Growth Rate ◽  
Carbon Source ◽  
Southern Hemisphere ◽  
Carbon Sink ◽  
Growing Season ◽  
Satellite Observations ◽  
Carbon Uptake ◽  
Co2 Fluxes ◽  
Abrupt Transition ◽  
The Tropics

Abstract. The year 2015 saw a record atmospheric CO2 growth rate associated with a weaker than usual land carbon sink. Paradoxically, it was also the greenest year since 2000 according to satellite observations of vegetation greenness. To reconcile these two seemingly paradoxical observations, we examined the patterns of CO2 fluxes using two atmospheric inversions. Inversion results indicate that the year 2015 had a higher than usual northern land carbon uptake in spring and summer, consistent with the greening anomaly. This higher uptake was however followed by a larger source of CO2 in autumn, suggesting a coupling between growing season uptake and late season release of CO2. For the tropics and Southern Hemisphere, a strong and abrupt transition toward a large carbon source for the last trimester of 2015 is discovered, concomitant with the El Niño development. This abrupt transition of terrestrial tropical CO2 fluxes between two consecutive seasons is the largest ever found in the inversion records.

Suicidal Behavior in Black South Africans

Crisis ◽  
2003 ◽  
Vol 24 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Lourens Schlebusch ◽  
Naseema B.M. Vawda ◽  
Brenda A. Bosch
Keyword(s):  
South African ◽  
Suicidal Behavior ◽  
Health Care Facilities ◽  
South African Society ◽  
South Africans ◽  
The Past ◽  
The People ◽  
Care Facilities ◽  
Black South Africans ◽  
To Come

Summary: In the past suicidal behavior among Black South Africans has been largely underresearched. Earlier studies among the other main ethnic groups in the country showed suicidal behavior in those groups to be a serious problem. This article briefly reviews some of the more recent research on suicidal behavior in Black South Africans. The results indicate an apparent increase in suicidal behavior in this group. Several explanations are offered for the change in suicidal behavior in the reported clinical populations. This includes past difficulties for all South Africans to access health care facilities in the Apartheid (legal racial separation) era, and present difficulties of post-Apartheid transformation the South African society is undergoing, as the people struggle to come to terms with the deleterious effects of the former South African racial policies, related socio-cultural, socio-economic, and other pressures.

Learning Zulu

2016 ◽  
Author(s):  
Mark Sanders
Keyword(s):  
Language Learning ◽  
Cultural History ◽  
South African ◽  
Press Coverage ◽  
African History ◽  
African Culture ◽  
The Past ◽  
Correct Form ◽  
Linguistic Purism

When this book's author began studying Zulu, he was often questioned why he was learning it. This book places the author's endeavors within a wider context to uncover how, in the past 150 years of South African history, Zulu became a battleground for issues of property, possession, and deprivation. The book combines elements of analysis and memoir to explore a complex cultural history. Perceiving that colonial learners of Zulu saw themselves as repairing harm done to Africans by Europeans, the book reveals deeper motives at work in the development of Zulu-language learning—from the emergence of the pidgin Fanagalo among missionaries and traders in the nineteenth century to widespread efforts, in the twentieth and twenty-first centuries, to teach a correct form of Zulu. The book looks at the white appropriation of Zulu language, music, and dance in South African culture, and at the association of Zulu with a martial masculinity. In exploring how Zulu has come to represent what is most properly and powerfully African, the book examines differences in English- and Zulu-language press coverage of an important trial, as well as the role of linguistic purism in xenophobic violence in South Africa. Through one person's efforts to learn the Zulu language, the book explores how a language's history and politics influence all individuals in a multilingual society.

A Review of Medical Waste Management in South Africa

2018 ◽  
Vol 10 (1) ◽  
pp. 34-45 ◽  
Author(s):  
Olaniyi FC ◽  
Ogola JS ◽  
Tshitangano TG
Keyword(s):  
South Africa ◽  
Waste Management ◽  
South African ◽  
Management Practice ◽  
National Policy ◽  
Medical Waste ◽  
African Government ◽  
The Past ◽  
Government Documents ◽  
Medical Waste Management

Background:Poor medical waste management has been implicated in an increase in the number of epidemics and waste-related diseases in the past years. South Africa is resource-constrained in the management of medical waste.Objectives:A review of studies regarding medical waste management in South Africa in the past decade was undertaken to explore the practices of medical waste management and the challenges being faced by stakeholders.Method:Published articles, South African government documents, reports of hospital surveys, unpublished theses and dissertations were consulted, analysed and synthesised. The studies employed quantitative, qualitative and mixed research methods and documented comparable results from all provinces.Results:The absence of a national policy to guide the medical waste management practice in the provinces was identified as the principal problem. Poor practices were reported across the country from the point of medical waste generation to disposal, as well as non-enforcement of guidelines in the provinces where they exit. The authorized disposal sites nationally are currently unable to cope with the enormous amount of the medical waste being generated and illegal dumping of the waste in unapproved sites have been reported. The challenges range from lack of adequate facilities for temporary storage of waste to final disposal.Conclusion:These challenges must be addressed and the practices corrected to forestall the adverse effects of poorly managed medical waste on the country. There is a need to develop a medical waste policy to assist in the management of such waste.

scholarly journals Predicting the past, present and future distributions of an endangered marsupial in a semi‐arid environment

2021 ◽  
Author(s):  
J. Riley ◽  
M.R.K. Zeale ◽  
O. Razgour ◽  
J. Turpin ◽  
G. Jones
Keyword(s):  
Arid Environment ◽  
The Past ◽  
Semi Arid

scholarly journals Afrikaans as universiteitstaal: Onlangse ontwikkelinge in historiese en internasionale perspektief

Literator ◽  
1994 ◽  
Vol 15 (1) ◽  
pp. 33-58 ◽  
Author(s):  
J. C. Steyn
Keyword(s):  
South African ◽  
Political Power ◽  
Language Community ◽  
Language And Culture ◽  
The Past ◽  
South African Universities ◽  
History Of ◽  
Official Status

A study of the history of South African universities from 1918 to 1948 showed that six factors influenced the use of a particular language as a language medium at a university, namely economic and political power, as well as the number of people in the language community (which determines matters such as the official status of the language and the availability of money for universities), lecturers' and students ’ knowledge of the language, its position as scholarly language, language loyalty and attitudes toward other languages and the support enjoyed by language and related ideologies. Whereas these factors were reasonably favourable for Afrikaans universities in the past, they currently pose a threat to the survival of Afrikaans-medium universities. The standpoint is defended that retaining Afrikaans as educational and scholarly language should be an important factor when making decisions on universities. The tension between internationalisation and retention of the own language and culture is also topical in Europe, and steps have been taken to try to protect the retention of Dutch as language medium at Dutch and Flemish universities.

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