Drought tolerant forb flora of a semi-arid protected savanna in the Lowveld of South Africa

Coller, Hennie Van; Klem, J.; Siebert, Frances

doi:10.38201/btha.abc.v51.i1.10

Cited by 6 publications

(3 citation statements)

References 25 publications

(37 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Consequently, PPF can provide cattle with forage at the end of the growing season when more favourable PPG are depleted (van der Merwe & Marshal, 2012). This result emphasises the importance of forbs in semi‐arid savanna rangelands contributing to forage stability under unfavourable conditions (van Coller et al., 2021).…”

Section: Discussionmentioning

confidence: 54%

Response of herbaceous functional types and woody vegetation to selective shrub control on wildlife and cattle ranches in a semi‐arid savanna

Marquart,

van Coller,

van Staden

et al. 2023

Applied Vegetation Science

Self Cite

View full text Add to dashboard Cite

AimsShrub encroachment is a major challenge for livestock and wildlife management in semi‐arid savannas. Shrub removal by land managers is widespread, but the long‐term effects on vegetation structure and composition, which determine carrying capacity for herbivores, are poorly documented. This study aims to examine the effects of selective shrub removal to guide vegetation management in key land uses of semi‐arid African savannas.QuestionsVegetation responses were assessed across land uses and treatments to answer the following questions: (1) does shrub removal increase the frequency of palatable plants and therefore herbivore‐carrying capacity; (2) does selective shrub removal decrease woody vegetation structure 15 years after application; and (3) how do these effects differ between cattle and wildlife ranching?LocationMolopo region of the North West Province, South Africa.MethodsHerbaceous and woody vegetations were sampled within six transects each of three wildlife ranches and three cattle ranches in areas that had either been selectively shrub‐controlled with herbicides 10–15 years previously or left untreated. To quantify effects of woody shrub control on herbaceous functional‐group abundances and assemblages, tree equivalents, regrowth rate, and shrub abundance, we compared these variables across two treatments (treated and untreated) and land uses. Data were analysed using GLMMs, NMDS ordinations, PERMANOVA, and SIMPER.ResultsSelective shrub control effectively improved palatable herbaceous vegetation, especially on cattle ranches. Especially abundance of perennial grass was higher on wildlife ranches compared to cattle ranches. Tree equivalent was higher in untreated compared to treated plots, and these differences were more pronounced on wildlife ranches than on cattle ranches.ConclusionssSelective shrub removal improved the palatable herbaceous layer for both wildlife and cattle ranching and can be considered an effective management strategy in semi‐arid rangelands.

show abstract

Section: Discussionmentioning

confidence: 54%

Response of herbaceous functional types and woody vegetation to selective shrub control on wildlife and cattle ranches in a semi‐arid savanna

Marquart,

van Coller,

van Staden

et al. 2023

Applied Vegetation Science

Self Cite

View full text Add to dashboard Cite

show abstract

“…Existing research typically only focuses on the relationship between climatic pressures and vegetation response, without accounting for the influence of ecosystem characteristics on how vegetation responds to different stressors. Furthermore, most recent studies on these environmental characteristics are site‐specific and rely on limited data (de Oliveira et al., 2019; Hartnett et al., 2013; Simpson et al., 2022; Van Coller et al., 2021; Wigley‐Coetsee & Staver, 2020). A comprehensive understanding of the interplay between ecosystem characteristics and pressures requires an expanded analysis framework.…”

Section: Introductionmentioning

confidence: 99%

Wetness severity increases abrupt shifts in ecosystem functioning in arid savannas

Vermeulen,

Verbist,

Van Meerbeek

et al. 2024

Global Change Biology

View full text Add to dashboard Cite

The accelerating pace of climate change has led to unprecedented shifts in surface temperature and precipitation patterns worldwide, with African savannas being among the most vulnerable regions. Understanding the impacts of these extreme changes on ecosystem health, functioning and stability is crucial. This paper focuses on the detection of breakpoints, indicative of shifts in ecosystem functioning, while also determining relevant ecosystem characteristics and climatic drivers that increase susceptibility to these shifts within the semi‐arid to arid savanna biome. Utilising a remote sensing change detection approach and rain use efficiency (RaUE) as a proxy for ecosystem functioning, spatial and temporal patterns of breakpoints in the savanna biome were identified. We then employed a novel combination of survival analysis and remote sensing time series analysis to compare ecosystem characteristics and climatic drivers in areas experiencing breakpoints versus areas with stable ecosystem functioning. Key ecosystem factors increasing savanna breakpoint susceptibility were identified, namely higher soil sand content, flatter terrain and a cooler long‐term mean temperature during the wet summer season. Moreover, the primary driver of changes in ecosystem functioning in arid savannas, as opposed to wetter tropical savannas, was found to be the increased frequency and severity of rainfall events, rather than drought pressures. This research highlights the importance of incorporating wetness severity metrics alongside drought metrics to comprehensively understand climate–ecosystem interactions leading to abrupt shifts in ecosystem functioning in arid biomes. The findings also emphasise the need to consider the underlying ecosystem characteristics, including soil, topography and vegetation composition, in assessing ecosystem responses to climate change. While this research primarily concentrated on the southern African savanna as a case study, the methodological robustness of this approach enables its application to diverse arid and semi‐arid biomes for the assessment of climate–ecosystem interactions that contribute to abrupt shifts.

show abstract

“…nutritious fodder for game and livestock, protein and vitamin rich food for human consumption and medicinal use, habitat for many arthropod species, indicator for habitat degradation and climate change (Siebert and Dreber 2019). Examples for forb species are: Amaranthus praetermissus, Gisekia africana, Helichrysum candolleanum, Indigastrum argyroides, Lotononis platycarpa, Microcharis disjuncta, and Trianthema parvifolia (Tainton 1999;Dreber et al 2011;Siebert and Dreber 2019;van Coller et al 2021).…”

Section: Vegetationmentioning

confidence: 99%

Modelling, management and restoration of savannas in southern Africa

Heß¹

View full text Add to dashboard Cite

Context -Bush encroachment has been observed in southern African savannas for several decades. This form of land degradation reduces the abundance of (palatable) grass biomass on farms, which in turn can support less livestock sustainably. A reduction in livestock usually results in lower income or less food for farmers and can therefore threaten livelihoods. The vegetation dynami cs of savannas are complex and multifactorially interconnected. Spatially explicit, process-oriented rangeland models are ideal tools to study these complex vegetation dynamics and the phenomenon of bush encroachment. These models can aid in optimizing management to reduce bush encroachment and give guidance to focus future research on the most relevant factors influencing vegetation processes and bush encroachment in savannas.Objectives -This dissertation aims to identify and examine the key factors that can cause and influence the emergence and expansion of bush encroachment in southern African savannas. To this end, we incorporated potentially important factors and processes in a simulation model to study their impact on bush encroachment and to be able to test different environmental and management scenarios with a focus on realistic vegetation dynamics and livestock management.Methods -To identify the potentially most important environmental and management factors that influence the vegetation dynamics of bush encroachment, we interviewed farmers and stakeholders, held workshops and had discussions with scientists and leading experts in the field.Through programming a landscape generator (PioLaG) and a process-oriented rangeland simulation model (Midessa), we gained the ability to set these influential factors and processes in relation to another and to observe and test their cause-and-effect relationship in terms of the impact on vegetation type distribution and livestock condition.Results -The most important factors that determine the current state of savanna rangelands are heterogeneous precipitation patterns, soil moisture, vegetation competition and succession, fire events, seed availability, grazing and browsing, wood reduction by firewood remo val or through arboricides, as well as other management factors such as livestock type and stocking density, type and characteristics of the grazing system, and farmer back-up plans for drought periods. Simulation results showed that introducing browsers and/or mixed feeders to a farm will greatly slow down bush encroachment. A grazer/browser mix thus seems to be a promising approach for a nonchemical management tool against bush encroachment. Careful and adaptive farming strategies including a sophisticated rotational grazing system, will improve vegetation conditions for livestock.Reducing the livestock density on a farm has also been found to slow down bush encroachment and delay the decline of livestock condition. From a modelling perspective , an interesting observation was that spatially heterogeneous distributed precipitation had a major impact on Abstract II simulation results ...

show abstract

Drought tolerant forb flora of a semi-arid protected savanna in the Lowveld of South Africa

Cited by 6 publications

References 25 publications

Response of herbaceous functional types and woody vegetation to selective shrub control on wildlife and cattle ranches in a semi‐arid savanna

Response of herbaceous functional types and woody vegetation to selective shrub control on wildlife and cattle ranches in a semi‐arid savanna

Wetness severity increases abrupt shifts in ecosystem functioning in arid savannas

Modelling, management and restoration of savannas in southern Africa

Contact Info

Product

Resources

About