Frances Siebert

Frances Siebert
North-West University | NWU ·  Unit for Environmental Sciences and Management

PhD

About

69
Publications
55,330
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606
Citations
Additional affiliations
April 2011 - present
North-West University
Position
  • Professor (Associate)
April 2011 - September 2015
North-West University
Position
  • Professor (Associate)

Publications

Publications (69)
Article
Full-text available
Evolvulus alsinoides (L.) L. (Convolvulaceae) is a forb species that is highly valued in traditional medicine for its memory-enhancing effects, and a range of other ethnomedicinal properties. However, there are no studies on the phytochemical composition and antioxidant activities of E. alsinoides collected in South Africa. The present study was de...
Article
Privately protected areas (PPAs) are internationally considered to be important policy implementation instruments to augment and strengthen protected area networks. However, there has been limited reflection on the performance of PPAs over time. This paper aims to identify key risks to the performance of PPAs as policy implementation instruments th...
Conference Paper
Decomposition is a major determinant of terrestrial nutrient cycling and therefore an important regulator of ecosystem structure and function. It has been widely documented that large mammalian herbivores (LMH) act as a significant driver of changes to aboveground structure and modifications to edaphic properties. Little is known about the role of...
Article
The genus Aloe has attracted considerable research attention in the last two decades owing to its ethnomedicinal, nutraceutical, pharmaceutical, and cosmeceutical importance. This review aimed to evaluate the performance of research outputs, identify evolving trends and research hotspots, and present a detailed summary of recent research reports on...
Article
Full-text available
Mallotus oppositifolius (Geiseler) Müll. Arg. (Euphorbiaceae) is an important and multipurpose medicinal herb found in different African countries. Its various parts possess several pharmacological activities. However, to date, there is no literature review collating the traditional uses, phytochemistry and biological activities of M. oppositifoliu...
Article
Ethnopharmacological relevance Sceletium tortuosum (L.) N.E.Br., the most sought after and widely researched species in the genus Sceletium is a succulent forb endemic to South Africa. Traditionally, this medicinal plant is mainly masticated or smoked and used for the relief of toothache, abdominal pain, as a mood-elevator, analgesic, hypnotic, anx...
Article
Fire and herbivory are major drivers in tropical savanna ecosystems and they selected a flora composed of species able to cope with recurrent aboveground biomass removal. Renewal of the herbaceous stratum is made possible by resprouting, mostly through a belowground bud bank. Evaluating the impacts of disturbances on the bud bank can assist in pred...
Poster
Full-text available
Grasslands are much more than just grass. Forbs (i.e., the non-graminoid herbaceous component) represent the largest proportion of total species- and functional richness in grassland ecosystems, which secure important ecosystem functions. Here, we present some highlights of only some of the important functions provided by this hyper-diverse plant l...
Article
Full-text available
The genus Merremia Dennst. ex Endl. (Convolvulaceae) is a rich source of structurally diverse phytochemicals with therapeutic relevance. This review presents the first comprehensive, up-to-date information and research progression on the nutritional value, ethnomedicinal uses, phyto-chemistry, pharmacological activities, and toxicity of the genus M...
Article
Ethnopharmacological relevance Sceletium tortuosum (L.) N.E.Br, the most sought after and widely researched species in the genus Sceletium is a succulent forb endemic to South Africa. Traditionally, this medicinal plant is mainly masticated or smoked and used for the relief of toothache, abdominal pain, and as a mood-elevator, analgesic, hypnotic,...
Article
Full-text available
Fire and herbivory are important natural disturbances in grassy biomes. Both drivers are likely to influence belowground microbial communities but no studies have unravelled the long-term impact of both fire and herbivory on bacterial and fungal communities. We hypothesized that soil bacterial communities change through disturbance-induced shifts i...
Article
Full-text available
Plant functional traits provide a valuable tool to improve our understanding of ecological processes at a range of scales. Previous handbooks on plant functional traits have highlighted the importance of standardising measurements of traits to improve our understanding of ecological and evolutionary processes. In open ecosystems (i.e. grasslands, s...
Article
Full-text available
Land-use effects on grassland flora are difficult to predict due to poor understanding of species losses caused by transformation.To determine changes in species diversity and composition by comparing transformed with untransformed grassland. Floristics of paired plots were sampled within 18 transformed sites (representing agricultural and urban...
Article
Full-text available
Background: Low altitude Mopaneveld savanna in the northeastern parts of South Africa is generally well conserved. However, extensive copper mining, agricultural practices and urbanisation in the Phalaborwa region prompted research on the possible effects of land-use change on plant community diversity and function. Species diversity measures are u...
Article
Full-text available
Background: Increased frequency and intensity of droughts related to climate change are predicted to induce pressure on herbaceous communities. Considering that forbs contribute significantly to savanna ecosystem resilience, we investigated forb communities of a protected semi-arid savanna during an extensive drought. Objective: We identified droug...
Article
Review of: William Bond. 2019, Oxford University Press, Great Clarendon Street, Oxford, OX2 6DP, UK 192 pages, Hardcover, Paperback, Ebook ISBN-13: 978-0198812456DOI:10.1093/oso/9780198812456.001.0001$78 (~ R 1 135, Hardcover); $85 (~R 1 240, Ebook); $46 (~R 660, Paperback)
Article
Full-text available
Background: Land-use effects on grassland flora are difficult to predict due to poor understanding of species losses caused by transformation.Objectives: To determine changes in species diversity and composition by comparing transformed with untransformed grassland.Methods: Floristics of paired plots were sampled within 18 transformed sites (repres...
Article
Full-text available
Background: Increased frequency and intensity of droughts related to climate change are predicted to induce pressure on herbaceous communities. Considering that forbs contribute significantly to savanna ecosystem resilience, we investigated forb communities of a protected semi-arid savanna during an extensive drought.Objective: We identified drough...
Article
Attempts to obtain standardised decomposition data to determine potential drivers of carbon release have evolved from the use of cotton strips and standardised leaf litter mixtures to the most recent Tea Bag Index (TBI). The TBI is an internationally standardised method to collect comparable, globally distributed data on decomposition rate and litt...
Article
Full-text available
Plant functional traits provide a valuable tool to improve our understanding of ecological processes at a range of scales. Previous handbooks on plant functional traits have highlighted the importance of standardising measurements of traits to improve our understanding of ecological and evolutionary processes. In open ecosystems (i.e. grasslands, s...
Article
Full-text available
Despite growing recognition of the conservation value of grassy biomes, our understanding of how to restore biodiverse tropical and subtropical grassy biomes (grasslands and savannas; TGB) remains limited. Several tools have recently been identified for TGB restoration including prescribed fires, appropriate management of livestock and wild herbivo...
Technical Report
Full-text available
Translation of the original article "Myth-busting tropical grassy biome restoration” published in Restoration Ecology Tradução do artigo original “Myth-busting tropical grassy biome restoration” publicado na Restoration Ecology que pode ser acessado aqui (https://onlinelibrary.wiley.com/doi/abs/10.1111/rec.13202?af=R). Em caso de citação, deve-se...
Article
Full-text available
The historical focus in research and policy on forest restoration and temperate ecosystems has created misunderstandings for the restoration of tropical and subtropical old-growth grassy biomes (TOGGB). Such misconceptions have detrimental consequences for biodiversity, ecosystem services and human livelihoods in woodlands, savannas and grasslands...
Article
Full-text available
Projected increases in the frequency and severity of drought events are expected to impose changes in the ecology of native forb communities in semi-arid ecosystems. We examined the state of forb communities during, and directly after an extreme drought event across two contrasting land-use types, which included a protected area (high diversity of...
Article
Full-text available
A major concern during the translocation of higher plant species is related to habitat suitability and the availability of pollination services. Should these not meet the requirements of the plant, then successful reproduction and establishment cannot occur. We studied an endangered succulent, Frithia humilis, which had previously been translocated...
Article
Full-text available
Rainfall and herbivory shape savannah herbaceous communities, but these disturbances are being altered globally. To assess potential consequences of such alterations, we evaluated herbivore effects on species and functional diversity during an episodic drought in a sodic savannah using data collected from long‐term herbivore exclosures in the Kruge...
Poster
Full-text available
South African grasslands are ancient and highly biodiverse. Habitat transformation through land-use change is threatening these grassland ecosystems. The loss of plant species per unit area cannot be quantified for transformed grasslands, as the richness of untransformed grasslands has not been determined accurately. The aim of this study was to de...
Preprint
Full-text available
Savannas are commonly described as a vegetation type with a grass layer interspersed with a discontinuous tree or shrub layer. On the contrary, forbs, a plant life form that can include any nongraminoid herbaceous vascular plant, are poorly represented in definitions of savannas worldwide. While forbs have been acknowledged as a diverse component o...
Presentation
The eastern savanna landscape within the Kruger National Park (KNP) is a well-studied, spatially heterogeneous savanna ecosystem characterized by various vegetation types, which are commonly linked to a north-south rainfall gradient combined with distinct geological variation across the park from east to west. In contrast, South Africa’s drier west...
Presentation
Full-text available
This presentation was presented by me at The 17th Annual Savanna Science Networking Meeting, hosted by SANParks' Scientific Services from 3 - 7 March 2019 in the Mdluli Conference Centre, Skukuza.
Article
Full-text available
Herbivores alter plant biodiversity (species richness) in many of the world’s ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet,...
Article
Full-text available
Long-term herbaceous vegetation data collected from herbivore and fire exclusion treatments in a nutrient-rich system in the Kruger National Park (KNP), South Africa were used to compare the response patterns of forbs and grasses to varying rainfall conditions. Palatable annual forbs consistently dominated over palatable annual grasses, whereas unp...
Presentation
The Griqualand West Centre of Endemism (GWC) is one of thirteen centres of plant endemism in southern Africa. The occurrence of 24 endemic plant species in the GWC is ascribed to the region’s topographic, climatic and geological heterogeneity. Vegetation types of the region are subsequently varied with eight vegetation units of the Eastern Kalahari...
Presentation
Low altitude Mopaneveld savanna in the northeastern parts of South Africa is generally well conserved. However, extensive copper mining, and associated agriculture and urbanisation in the Phalaborwa region prompted research on the possible effects of land-use change, specifically soil disturbances of various magnitudes on plant community structure...
Thesis
Full-text available
Ecological conservation of savanna ecosystems is dependent upon interactive mechanisms involving bottom-up drivers such as nutrient availability, and top-down controls relating to fire, herbivory and water availability at various spatial scales. Alterations in diverse savanna herbivore communities, suppression of natural fire regimes and increased...
Poster
Full-text available
The Griqualand West Centre of Endemism (GWC) is one of thirteen centres of plant endemism in southern Africa. Driven by topography, climate and geological heterogeneity, the GWC hosts 24 endemic plant species. Vegetation types in the region are remarkably rich in plant species while eight vegetation units of the Eastern Kalahari Bushveld Bioregion...
Article
Strip mining alters the natural ecosystem and is especially detrimental in semi-arid regions, such as Mopaneveld. We need to understand the dynamic nature of recovery after a major disturbance, to be able to inform mitigation measures to assist those ecological processes and functions which did not recover sufficiently. Recovery of these ecosystem...
Conference Paper
Full-text available
Ecological studies designed to explain vegetation dynamics and veld condition in semi-arid and arid (dryland) savannas often focus on the interaction between the grassy and woody component, while their interaction with forbs are generally weakly represented. Forbs contribute to a range of ecosystem services and functions for wildlife, livestock and...
Research
Full-text available
Understanding relationships between large herbivores and plant species diversity in dynamic riparian zones, and more specifically sodic zones, is critical to biodiversity conservation. Sodic patches form an integral part of savanna ecosystems because of the ecosystem services and functions they provide, i.e. accumulation of nutrients, provision of...
Article
Ecological models to explain savanna heterogeneity and functioning weakly represent herbaceous forbs, which inevitably created knowledge gaps regarding the diversity and ecology of forbs. Forbs constitute over 70% of semi-arid savanna species richness. The aim of this study was therefore to (i) identify forb species that potentially form part of he...
Article
Full-text available
The hump-back relationship between species diversity and productivity predicts highest species richness at intermediate levels of biomass, and low species numbers in least and most productive habitats. Sodic patches of semi-arid savannas are considered ‘nutrient hotspots’ by producing high-quality forage. The impact of biomass reduction (due to ove...
Presentation
Biodiversity maintains ecosystem functions and provides ecosystem services. Human-induced transformation of natural vegetation can reduce diversity, and ultimately ecosystem services. Land-use and transformation is therefore considered one of the most important agents of global change. The Phalaborwa-Timbavati Mopaneveld is a semi-arid savanna type...
Article
Full-text available
A classification of the woody component of the riparian vegetation of Zululand coastal thornveld is analysed using the height classes of different woody species as an indication of age. A total of 43 randomly stratified plots was selected using aerial photographs to include all the different plant communities in this rare and endemic vegetation typ...
Poster
Full-text available
SAEON is concerned with the provision of reliable long-term data as well as monitoring environmental change, especially in Mopaneveld - an event driven and dynamic system. A long term monitoring project was initiated to detect changes in the diversity and composition of the herbaceous layer of Syenite koppies in the Mopaneveld. It is hypothesized t...
Article
Full-text available
Understanding relationships between large herbivores and plant species diversity in dynamic riparian zones is critical to biodiversity conservation. The Nkuhlu exclosures in the Kruger National Park (KNP) provided opportunity to investigate spatial heterogeneity patterns within riparian zones, as well as how these patterns are affected by fire and...
Article
Full-text available
Savanna ekosisteme in Suid-Afrika word gekenmerk deur heterogeniteit op verskeie skale
Article
Full-text available
Die groot vloede wat in die jaar 2000 in die Kruger Nasionale Park plaasgevind het, het dierivieroewerplantegroei versteur. Dit het die geleentheid gebied om heinings op te rig langsdie Sabierivier om herbivore uit sekere gebiede uit te sluit en sodoende die herstel van die rivieroewerekosisteme te monitor.
Article
Full-text available
The distinctiveness of Maputaland Woody Grassland lies within its richness of geoxylic suffrutices and herbaceous flora. Since it is well documented in the literature and easy to distinguish from other grassland types, it was possible to confirm a locality of this unique vegetation unit west of Richards Bay, where it probably forms the southernmost...
Article
Full-text available
The construction of exclosures along two of the most important rivers in the Kruger National Park was done to investigate how patterns of spatial and temporal heterogeneity of the riparian zone is affected by fire, flood and herbivory. To assist this research programme, vegetation surveys were conducted within exclosures along the Letaba River to c...
Article
Full-text available
The need to conduct research on the impact of elephant on the environment prompted the construction of exclosures along two of the most important rivers in the Kruger National Park. Scientific research on these exclosures along the Sabie and Letaba rivers addresses how patterns of spatial and temporal heterogeneity of the riparian zone are affected...
Article
Full-text available
A classification of the woody component of the riparian vegetation of Zululand coastal thornveld is analysed using the height classes of different woody species as an indication of age. A total of 43 randomly stratified plots was selected using aerial photographs to include all the different plant communities in this rare and endemic vegetation typ...
Article
Full-text available
This is an extract of this Grassland Biome chapter from the pre-publication PDF of the book Mucina, L., & Rutherford, M.C. (eds). Reprint 2011. The Vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African Biodiversity Institute, Pretoria. ISBN: 978-1919976-21-1
Article
Full-text available
An analysis of the vegetation of the Sterkfontein Caves (i.e. the natural area surrounding the caves) is presented. Relevés were compiled in 24 stratified random sample plots. A TWINSPAN classification, refined by Braun-Blanquet procedures, revealed six plant communities, also referred to as vegetation units. For each of these vegetation units the...
Article
Full-text available
A vegetation survey was conducted of the Owen Sitole College of Agriculture (OSCA). Phytosociological data were used to identify plant communities and to determine alpha diversity. Five plant communities were recognised and described. One of these was sub-divided into two sub-communities. An ordination scatter diagram of the distribution of the six...
Article
Full-text available
Data from fifteen phytosociological studies were merged and classified to describe and compare the vegetation of geographically separated and climatically different Mopaneveld types in South Africa, Namibia and Zimbabwe. Seven vegetation types and ten major plant communities were identified using TWINSPAN. Vegetation types were separated according...
Article
Full-text available
A hierarchical classification, description, and ecological and floristic interpretations are presented on the vegetation types of the ultramafic rock habitats of the Sekhukhuneland Centre of Plant Endemism. Relevés were compiled in 100 stratified random plots. A TWINSPAN classification, refined by Braun-Blanquet procedures, revealed 17 plant commun...
Article
Full-text available
A hierarchical classification, description, and ecological and floristic interpretations are presented on the vegetation types of the grasslands and wetlands of the Sekhukhuneland Centre of Plant Endemism. Relevés were compiled in 74 stratified random plots. A TWINSPAN classification, refined by Braun-Blanquet procedures, revealed eight association...
Article
Full-text available
Frithia N.E.Br. (Mesembryanthemaceae), formerly thought to be a monotypic genus, has been found to comprise two species. Populations from the eastern parts of the distribution range of Frithia pulchra N.E.Br. are recognised as a distinct species, Frithia humilis P.M. Burgoyne. The genus has a limited distribution, although present in three province...
Article
Thesis (M. Sc.)(Botany)--University of Pretoria, 2001.

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Projects (2)
Project
To improve the scientific understanding of Ecosystem Resilience through the application of forb ecology research in tropical and subtropical grassy ecosystems
Project
Livestock farming in the Limpopo region of South Africa takes place in arid and semi-arid rangelands that are characterised by low and erratic rainfall and regular droughts. Intensive herbivore grazing under these conditions exerts extra pressure on the ecosystem, resulting in an increase in levels of soil and vegetation degradation. Besides, climate change models predict decreasing predictability and amount of rainfall, as well as increasing frequency of more extreme drought events in this region. These pressures are expected to increase in these areas as a result of the projected frequent droughts. The Subproject 4 of the Limpopo Living Landscapes project focuses on the complex relationships between grazing and drought impacts on the herbaceous vegetation in the savanna and grassland biome of the Limpopo region. This vegetation is exceptionally rich in species, and grazing activity is needed for maintaining its high diversity. Thus, an ecologically oriented management is required to increase livestock production while conserving vegetation diversity and the functioning of the ecosystem to prevent landscape degradation. Despite its importance, the relationships between the impact of drought and grazing on the vegetation have seldom been studied in the Limpopo region or in semi-arid savanna and grassland biome in general. In order to study the interactive effects these factors on rangeland vegetation, an experimental manipulation of precipitation (artificial drought) and grazing is currently carried out at the Syferkuil Experimental Farm, University of Limpopo – South Africa.