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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 land-uses) and neighbouring untransformed grassland. Endemic and threatened species were negatively affected by transformation, particularly species with belowground bud-banks and storage organs. Species composition, with clear shifts in dominant families, was changed by over 90% on average by transformation. Land-use transformation lead to the loss of native species and increased alien invasive species.
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BOTHALIA – African Biodiversity & Conservation
ISSN: (Online) 2311-9284, (Print) 0006-8241
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1M. Muller 
1S.J. Siebert 
2B.R. Ntloko 
1F. Siebert 
1Unit for Environmental Sciences
and Management, North-West
University, Private Bag X6001,
Potchefstroom 2520, South
2Letšeng Diamonds, cnr Kingsway
and Old School Road Maseru,
P.O. Box 12508, Maseru 100
Corresponding Author
Prof. S.J. Siebert,
Submitted: 20 September 2019
Accepted: 1 December 2020
Published: 24 February 2021
How to cite this article:
Muller, M., Siebert, S.J., Ntloko, B.R.
& Siebert, F., 2021, ‘A oristic
assessment of grassland
diversity loss in South Africa’,
Bothalia 51(1), a11. http://dx.doi.
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 com-
paring transformed with untransformed grassland.
Methods: Floristics of paired plots were sampled within 18 transformed sites
(representing agricultural and urban land-uses) and neighbouring untransformed
Results: Endemic and threatened species were negatively affected by transfor-
mation, particularly species with belowground bud-banks and storage organs.
Species composition, with clear shifts in dominant families, was changed by over
90% on average by transformation.
Conclusion: Land-use transformation lead to the loss of native species and in-
creased alien invasive species.
Land-use change threatens the persistence of many grassland ecosystems
worldwide (Bond 2016). Grasslands are hyper-diverse ancient ecosystems,
habitats and communities, supporting many endemic and threatened species
(Carbutt, Henwood & Gilfedder 2017). Habitat transformation threatens the
integrity of these systems through soil disturbance and the removal of plant
biomass and species, and the effect is widely recognised and measurable (Her-
ben, Chytrý & Klimešová 2016; Miller, Roxburgh & Shea 2011). The poor
understanding of forb dynamics in grassland necessitates a closer look at flo-
ristic change and whether land-use change leads to species losses or gains in
transformed grassland (Veldman et al. 2015).
In South Africa the Grassland Biome covers approximately one third of the land
surface (Carbutt et al. 2011). The extent of grassland is defined on the basis of
vegetation structure, as well as environmental factors including mean summer
rainfall and minimum winter temperatures (Mucina & Rutherford 2006). The
Grassland Biome is one of the most at-risk South African biomes, with 40–60%
irreversibly modified, and less than 3% formally protected (Little, Hockey &
Jansen 2015). The intactness of unprotected South African grasslands is threat-
ened as there is an increase in the intensity of agriculture and afforestation
(O’Connor & Kuyler 2009; Botha et al. 2017) and urban and industrial devel-
opment activities (Siebert, Van Wyk & Bredenkamp 2001; O’Connor & Kuyler
2009). Changes in composition, structure and functioning of these grasslands
influence the ability to deliver fresh water, soil formation, climate regulation
and reduction of disaster risk (Egoh et al. 2011), and in addition, probable loss
of biodiversity and grassland production (Everson & Everson 2016).
A oristic assessment of grassland
diversity loss in South Africa
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O’Connor and Kuyler (2009) have meticulously investi-
gated the impact of land-use on the biodiversity integ-
rity of moist grasslands in South Africa and highlighted
the loss of useful plants from an ecosystem services
perspective. Our study focusses on biodiversity intact-
ness in that it specifically considers loss of native floristic
diversity. It places special emphasis on the indigenous
forb component that is fast moving up the research
agenda (Siebert & Dreber 2019).
Materials and methods
Study area
Eighteen study sites were selected in four bioregions of
the Grassland Biome, as well as a tropical bioregion of
the Indian Ocean Coastal Belt Biome of South Africa
(Figure 1). The chosen grasslands occurred at altitudes
ranging between 30 and 3 100 m above sea level, with
ten sites between 1 000 and 1 800 m. The mean annu-
al temperature for the grassland sites ranged from 10 to
21°C, with an overall mean of 16.3°C (median 15.9°C).
June to August are the coldest months with mean frost
days per annum varying between 0 and 96, with a
mean of 25 (median 28) across all study sites (Mucina
& Rutherford 2006). All sites experience summer rain-
fall ranging from 600 to 1 000 mm per year and a mean
of 761 mm (median 717 mm) across sites. Twelve sites
receive less than 800 mm per annum.
Field surveys
Two dominant land transformation types in the Grass-
land Biome were included in this study, namely agri-
culture and urbanisation (Neke & Du Plessis 2004).
Floristic data were gathered from 18 sites. At each site,
sampling was conducted in four plots in untransformed
grassland, each paired with a plot in an adjacent trans-
formed land-use (i.e. eight plots per site), no more than
150–250 m apart. All 144 plots were surveyed in late
spring or early to mid-summer. Each 100 m2 plot was
divided into 25 subplots of 4 m2 each to record species
occurrence and abundance. Species were identified in
the field and photos were taken for later confirmation.
Floristic data from the subplots were combined to com-
pile a total inventory for each 100 m2 plot.
Plant species nomenclature and classification follow
Ranwashe (2019). Naturalised and invasive categories
are according to Department of Environmental Affairs
(2016). Life and growth forms of plant species were
Figure 1. Location of the 18 study sites in the Grassland Biome of South Africa. Land-use transformation at localities: Agriculture, af-
forestation: 1, 2, 3; field margins: 4, 5, 6; abandoned fields: 7, 8, 9; urban, green space: 10, 11, 12; peri-urban: 13, 14, 15; mine
rehabilitation: 16, 17, 18.
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obtained from Germishuizen and Meyer (2003). Cate-
gories of threat were obtained from the Red Data List
of South African Plants (South African National Biodi-
versity Institute 2017).
Species abundance (N) was calculated as the total
number of individuals and species richness (S) as the
total number of species within each 100 m2 plot. The
Shannon–Wiener (H’) and Pielou (J’) indices were ap-
plied to plot data to calculate alpha diversity and even-
ness respectively. All above values were calculated us-
ing Primer (2007).
Data analysis
Non-Metric Multi-Dimensional Scaling (NMDS) anal-
ysis in Primer (2007) was used to explore changes in
species composition between transformed and un-
transformed grasslands. Permutational Multivariate
Analysis of Variance (PERMANOVA) was performed us-
ing species abundance data. Analyses were conducted
with 999 permutations using Bray–Curtis similarity and
Type III sums of squares after a square root transforma-
tion of species data to reduce the influence of common
species. To account for location variability in the paired,
nested sampling design, plots were treated as a random
variable nested within a transformation type (i.e. urban
or agricultural), which were treated as the fixed factor.
Pair-wise test results indicated the strength of the dif-
ference between transformed and untransformed plots.
Similarity Percentage Analysis (SIMPER) was applied
to determine which forb and grass species contribut-
ed the most to differences between transformed and
untransformed grasslands. Simple paired t-tests were
applied to test for significant differences between un-
transformed and transformed plots for selected diver-
sity measures. Percentage decrease in richness and
abundance of species per growth/life form, threat sta-
tus, endemism and for alien taxa was calculated from
the statistical means.
Overall, 1 146 plant species were recorded, of which
144 were non-native. The untransformed grassland
contained 962 species, which included 35 naturalised
and 15 invasive taxa (5%), 175 South African endemics
(18%) and 20 threatened species (2%). The transformed
grasslands had 582 species, including 92 naturalised
and 46 invasive taxa (24%), 47 South African endemics
(8%) and six threatened species (1%).
The most prominent families in the localities were the
Asteraceae, Poaceae, Fabaceae and Cyperaceae in or-
der of most species diverse (Table 1), whereas the Poa-
ceae were most abundant (Table 2). It is evident that
transformation is less favourable to the Asteraceae and
Fabaceae, and more beneficial to the Cyperaceae and
especially the Poaceae.
Habitat transformation affects the number of species
present per family. The geophytic Hyacinthaceae and
Iridaceae showed the largest species losses (18 and 19
species respectively) when grassland is transformed and
Table 1. Top ten families of untransformed and transformed grasslands based on the proportion of each family’s contribution to the total
species pools of 962 and 582 respectively. Superscripts indicate up or down movement in ranking in transformed grassland
Family Proportion of all species (%) Shift in
Untransformed Transformed ranking
Asteraceae 20,4 19,6 1 / 1
Poaceae 12,9 17,1 2 / 2
Fabaceae 10,2 10,1 3 / 3
Cyperaceae 3,6 3,1 4 / 4
Apocynaceae 3,2 1,7 5 / 10 ˅5
Malvaceae 2,5 2,9 6 / 5 ˄1
Scrophulariaceae 2,4 1,5 7 / 11 ˅4
Iridaceae 2,3 0,7 8 / 23 ˅15
Hyacinthaceae 2,2 0,5 9 / 31 ˅22
Lamiaceae 2,1 1,9 10 / 7 ˄3
Amaranthaceae 0,5 2,4 30 / 6 ˄24
Solanaceae 0,6 1,8 36 / 9 ˄27
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the weedy Amaranthaceae and Solanaceae benefitted
in terms of species additions (9 and 5 species respec-
tively; Table 1). Changes in the frequency of species is
even more pronounced (Table 2). Five of the top ten
families that have high frequencies of occurrence in un-
transformed grassland become reduced in transformed
grassland by 73%. These are replaced by five families,
which in turn showed a 75% increase in transformed
grassland (Table 2).
Changes in the species number and frequency of fam-
ilies is expected to have an effect on the composition
of transformed grassland. The results from a NMDS re-
vealed clustering that supports the untransformed and
transformed grasslands as separate assemblages (Figure
2). Results from the pair-wise tests in PERMANOVA in-
dicated a significant difference in floristic composition
between transformed and untransformed grasslands in
both urban (df = 70, t = 2.17, p = 0.001) and agri-
cultural (df = 70, t = 2.88, p = 0.001) transformation
types (Figure 2). Bray Curtis similarity measures in the
PERMANOVA design reported a low 6.96% and 5.7%
similarity in species composition between transformed
and untransformed agricultural and urban grasslands
respectively. This implies that transformation changed
species composition in grasslands by ~90% on average.
Fifteen most common grass species explained 21.26%
of the dissimilarity between transformed and untrans-
formed grasslands, with species such as Cynodon dacty-
lon and Hyparrhenia hirta weighted towards the former
and Digitaria eriantha and Themeda triandra towards
the latter (Table 3). Comparatively the first 15 forbs spe-
cies only contributed 8.52% to the dissimilarity, with
species such as Cyperus esculentus and Richardia brasil-
iensis weighted towards transformed, and Helichrysum
rugulosum and Scabiosa columbaria towards untrans-
formed grassland (Table 3).
Changes in the species composition are expected
to have an effect on species richness and diversity in
transformed grassland. Simple paired t-tests revealed
significantly lower diversity (for all measures, i.e. J’, H’,
S and N) in the transformed grassland (p<0.001, Table
4). Species richness decreased by nearly 50%.
The lower evenness in transformed grassland indi-
cates uneven proportional contribution of individuals
between species and is indicative of some species be-
coming more dominant and others becoming marginal.
Dominance shifts can be ascribed to increased numbers
of alien, invasive and annual species in the transformed
Table 2. Top ten families of untransformed and transformed grasslands based on the proportion of each family’s contribution to total
recorded individuals of 20 640 and 12 042 respectively. Superscripts indicate up or down movement in ranking in transformed
Family Proportion of all individuals (%) Shift in
Untransformed Transformed ranking
Poaceae 40,2 43,9 1 / 1
Asteraceae 18,3 15,2 2 / 2
Fabaceae 8,4 7,3 3 / 3
Cyperaceae 2,9 3,1 4 / 4
Rubiaceae 2,3 2,2 5 / 6 ˅1
Acanthaceae 2,0 0,5 6 / 19 ˅13
Malvaceae 1,6 1,3 7 / 12 ˅5
Hyacinthaceae 1,5 0,1 8 / 47 ˅39
Commelinaceae 1,2 1,2 9 / 13 ˅4
Lamiaceae 1,2 0,3 10 / 28 ˅4
Verbenaceae 0,6 2,6 22 / 5 ˄17
Amaranthaceae 0,2 2,1 47 / 7 ˄40
Brassicaceae 0,1 1,9 50 / 8 ˄42
Solanaceae 0,3 1,8 33 / 9 ˄24
Myrtaceae 0,25 1,7 36 / 10 ˄26
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grassland, with the former two being >80% lower in
untransformed grassland (Table 4). Threatened and en-
demic species richness and abundance decreased by
>80% in the transformed grassland (Table 4).
Growth forms
When aliens displace extant species (including endem-
ics), certain growth forms become more or less prom-
inent. Species losses (Table 4) were recorded for spe-
cies with underground storage organs and bud-banks
(USOs), such as geophytes (>80%), parasitic plants
and suffrutices (>90%). Succulents were considered
separately from the dwarf shrub growth form and were
also decreased by over 90% in transformed grasslands
(Table 4).
Asteraceae and Fabaceae were the most dominant forb
families in both transformed and untransformed grass-
land, a trend that has previously been reported (Botha
et al. 2017). It can be deduced that regenerative traits,
such as wind dispersal and seed dormancy for rapid
colonisation (Asteraceae), ballochory and/or or endozo-
ochory as seed dispersal traits, and resource acquisition
traits, which increase resprouting capacity (Fabaceae),
make them rather resilient to disturbance. However,
the Amaranthaceae, Brassicaceae, Solanaceae and
Verbenaceae benefit from the transformation of grass-
lands and their numbers and dominance increase
through the introduction of weedy, mostly alien, spe-
cies. These groups are renowned for their ability to
colonise frequently transformed man-made habitats
(Pysek, Prach & Smilauer 1995). In contrast, certain
families, such as the geophytic Hyacinthaceae and
Iridaceae, were extensively disadvantaged by habitat
transformation, as they are sensitive to soil disturbance
because their bud-banks are belowground (Fidelis et al.
2014). The general trend is therefore one of species loss
and displacement by a new flora, mostly annuals, with
colonising traits better suited to a transformed environ-
ment, such as creepers, clonal plants and fruit or seed
adapted for exozoochorous or anemochorous dispersal
(Botha et al. 2017).
Many species of ancient grasslands are not tolerant to
anthropogenic disturbance (Siebert 2011). Common
native species disappeared completely where grass-
lands were transformed, such as the grasses Alloterop-
sis semialata (R.Br.) Hitchc. and Schizachyrium san-
guineum (Retz.) Alston, forbs Gerbera ambigua (Cass.)
Sch.Bip. and Haplocarpha scaposa Harv., geophytes
Ledebouria luteola Jessop and Hypoxis argentea Harv.
ex Baker., dwarf shrubs Athrixia phylicoides DC. and
Tephrosia capensis (Jacq.) Pers., and suffrutices Ele-
phantorrhiza elephantina (Burch.) Skeels and Ziziphus
zeyheriana Sond. Other species, such as the palatable
and productive grass, Themeda triandra, which is con-
sidered a keystone species and indicator of undisturbed
grassland (Snyman, Ingram & Kirkman 2013), were
Figure 2: Non-Metric Multidimen-
sional Scaling (NMDS) ordina-
tion for: A, transformed and
untransformed grasslands; B,
within land-use type transfor-
mation. Squares, transformed
grasslands; circles, untrans-
formed grasslands; Empty sym-
bols, urban sites; filled symbols,
agricultural sites.
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severely reduced. Many new, mostly alien species,
enter the transformed system, providing species that
can be considered indicators of disturbance (Morris &
Scott-Shaw 2019), such as the prostrate and grazing-
resistant, Richardia brasiliensis. This study confirmed the
results of O’Connor (2015) that a substantial decrease
in T. triandra and increase in R. brasiliensis are indica-
tive of transformed grassland.
As previously shown, untransformed grasslands have
greater plant species diversity (27%) and richness (92%)
than transformed grasslands (O’Connor 2005; Siebert
Table 3. Similarity percentage analyses (SIMPER) of grass species contributing >0.6% to compositional differences between transformed
and untransformed grasslands. Bold values indicate highest mean abundance. * denotes alien taxa. Superscripts: G, grass; F, forb
Species Av. Cont. Cum. Mean abundance
dis. % % Transf. Untransf.
Themeda triandra Forssk.G2.92 3.067 3.07 1.32 13
Cynodon dactylon (L.) Pers. G 1.853 1.947 5.01 7.85 2.21
Eragrostis curvula (Schrad.) Nees G 1.768 1.858 6.87 5.63 4.85
Eragrostis plana Nees G 1.731 1.818 8.69 5.13 4.32
Hyparrhenia hirta (L.) Stapf G 1.457 1.531 10.22 5.35 2.63
Digitaria eriantha Steud. G 1.326 1.393 11.61 2.43 4.93
Setaria sphacelata (Schumach.) Moss G 1.179 1.239 12.85 1.28 4.89
Aristida junciformis Trin. & Rupr. G 1.148 1.206 14.06 0.74 5.24
Sporobolus africanus (Poir.) Robyns & Tournay G 1.145 1.203 15.26 4.79 0.94
Eragrostis chloromelas Steud. G 1.117 1.173 16.44 1.1 4.56
Pennisetum clandestinum Hochst. ex Chiov. G * 1.115 1.172 17.61 4.65 0
Heteropogon contortus (L.) Roem. & Schult. G 1.109 1.165 18.77 0.17 5.07
Tristachya leucothrix Trin. Ex Nees G 1.014 1.066 19.84 0.9 4.31
Richardia brasiliensis Gomes F * 0.755 0.793 20.63 3.07 0.35
Helichrysum rugulosum Less. F 0.752 0.79 21.42 0.56 3.25
Eragrostis racemosa (Thunb.) Steud. G 0.709 0.745 22.17 0.13 3.1
Cyperus esculentus L. F * 0.695 0.73 22.89 3.1 0.04
Helichrysum nudifolium (L.) Less. F 0.653 0.686 23.58 0.38 2.86
Eragrostis capensis (Thunb.) Trin. G 0.648 0.681 24.27 0.33 2.85
Sisymbrium turczaninowii Sond. F 0.637 0.67 24.94 2.61 0.15
Nidorella podocephala (DC.) Goldblatt & J.C.Manning F0.62 0.652 25.59 0.93 2.17
Hilliardiella oligocephala (DC.) H.Rob. F 0.516 0.542 26.13 0.17 2.26
Tagetes minuta L. F * 0.501 0.526 26.66 2.18 0.07
Scabiosa columbaria L. F 0.487 0.511 27.17 0.38 2.07
Conyza bonariensis (L.) Cronquist F * 0.484 0.509 27.68 1.75 0.4
Commelina africana L. F0.442 0.464 28.14 0.49 1.78
Felicia muricata (Thunb.) Nees F 0.412 0.433 28.57 0.25 1.61
Plantago lanceolata L. F 0.397 0.417 28.99 1.57 0.42
Bidens pilosa L. F * 0.393 0.412 29.41 1.68 0.03
Zornia capensis Pers. F 0.372 0.391 29.79 0.18 1.6
Av. dis.: Average dissimilarity; Cont. %: Contribution %; Cum. %: Cumulative contribution %; Transf.: Transformed; Untransf.: Untrans-
formed. Distance/Similarity measure: Bray-Curtis.
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2011). Species loss was specific to certain growth forms
with underground organs specifically adapted to survive
harsh winter conditions, drought and fire (Bond & Parr
2014; Bond 2016). The loss of these and other foun-
dation species open up niches for colonisation by alien
species (Prevéy et al. 2010). This is problematic, as loss
of native species hampers the grassland ecosystem from
fulfilling all its functions (Zavaleta et al. 2010). Overall,
the situation in transformed grassland is not only one of
species depletion, but increases in woody growth form
dominance is predicted to become more pronounced
in South African grasslands by 2030 (Gibson et al. 2018).
Table 4: Mean values (±SD) of selected diversity measures, growth forms, and alien, threatened and endemic species per plot. Percent-
age decrease is given in brackets. T-test results are reported for diversity measures, with significance set at p < 0.05
Measure Untransformed Transformed df t p
Pielou’s evenness (J’) 0.903 ±0.05 0.849 ±0.08 (6%) 142 4.92 <0.001*
Shannon Diversity Index (H’) 3.595 ±0.2 2.823 ±0.4 (21.5%) 142 13.93 <0.001*
Total species (S) 54.7 ±10.2 28.5 ±7* (47.9%) 142 17.9 <0.001*
Alien 0.9 ±1.1* (87%) 6.9 ±4.4
Invasive 0.5 ±0.9* (82.8%) 2.9 ±3.2
Threatened 0.5 ±0.7 0.1 ±0.4* (80%)
Endemic 6.7 ±3.2 1.3 ±1.4* (80.6%)
Annual 4.7 ±3.4* (39%) 7.7 ±5.4
Perennial 49.9 ±9.3 20.8 ±8.3* (58.3%)
Grass 13.4 ±5.1 7.9 ±3.6* (40.3%)
Geophyte 5.1 ±2.5 0.9 ±0.9* (80.4%)
Forb 23.5 ±5.2 12.3 ±4.4* (47.7%)
Parasitic 5.8 ±2.8 0.1 ±0.3* (98.3%)
Creeper 1.6 ±1.3 0.9 ±1.2 (43.8%)
Dwarf shrub 6 ±2.7 1.6 ±1.3* (73.3%)
Succulent 5.8 ±2.8 0.3 ±0.6* (94.8%)
Suffrutex 5.8 ±2.8 0.1 ±0.4* (98.3%)
Tree/shrub 5.9 ±2.7 4.2 ±6.2 (28.8%)
Total individuals (N) 286.7 ±64 167.3 ±40.8* (41.6%) 142 13.36 <0.001*
Alien 3.6 ±6.9* (90.4%) 37.4 ±26.2
Invasive 1.6 ±3.4* (92.3%) 20.8 ±22.9
Threatened 1.7 ±3.1 0.3 ±0.9* (82.4%)
Endemic 29.2 ±17.1 7.4 ±15.1* (74.7%)
Annual 19.4 ±16.2* (52.8%) 41.1 ±36.3
Perennial 267.3 ±63.5 126.1 ±52.5* (52.8%)
Grass 115.3 ±48.7 73.4 ±35.3* (36.4%)
Geophytic 17.6 ±11.8 3.2 ±4.6* (81.8%)
Forb 104.2 ±36.2 58.6 ±29.1* (43.8%)
Parasitic 23.7 ±14.4 0.2 ±0.6* (99.2%)
Creeper 5.3 ±6.4 3.1 ±4.1 (41.5%)
Dwarf shrub 24.8 ±14.1 5.9 ±7.8* (76.2%)
Succulent 23.7 ±14.4 1.1 ±2.6* (95.4%)
Suffrutex 23.8 ±14.4 0.2 ±1.7* (99.2%)
Tree/shrub 24.1 ±14.1 21.5 ±27.6 (10.8%)
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Major plant families remain floristically dominant after
transformation, but there is a negative impact on over-
all phylogenetic diversity and the promotion of the Poa-
ceae and Cyperaceae. Non-typical grassland families,
with a wide array of disturbance-tolerant traits, show
an increase in phylogenetic diversity, which is main-
ly a consequence of the introduction of alien weedy
Species composition of grassland was transformed by
disturbance and is indicative of better adapted spe-
cies entering the system or existing pre-adapted ones
becoming more dominant due to competition release
and/or altered microclimates and soils (Pysek, Prach &
Smilauer 1995). This is evidenced by the proportion of
grass species increasing, but a large reduction in forb
species with USOs (Fidelis et al. 2014). No evidence
was found for extensive woody encroachment in trans-
formed areas.
This study set out to assess species loss due to trans-
formation and, based on the current data set, it can
be conclusively stated that grassland is severely im-
pacted in terms of its species richness and diversity.
These changes are of concern as grasslands have high
economic value and support the wellbeing of humans
by providing, among others, ecological infrastructure,
carbon sinks, albedo surfaces, plant-based medicines,
food plants and grazing for livestock (Bengtsson et al.
2019). Further studies are needed to determine wheth-
er these floristic shifts can still maintain and provide the
ecosystem services that are expected from grasslands in
South Africa.
Our appreciation to Dr Monique Botha, Dr Elandrie
Davoren and Mr Paul Janse van Rensburg for making
plot data available for this study, and to Mr Wynand
Muller for producing the locality map. The South Af-
rican National Biodiversity Institute, South African En-
vironmental Observation Network, National Research
Foundation of South Africa and Letšeng Diamond
Mine, Lesotho, provided financial support to the re-
searchers and students involved in this project.
Authors’ contributions
MM collected field data, conducted data analyses
and contributed to the writing of the manuscript. SJS
planned and coordinated the study, collected field
data, conducted data analyses and co-wrote the manu-
script. BRN planned and coordinated part of the study,
collected field data, and conducted data analyses. FS
collected field data and contributed to the writing of
the manuscript.
The views expressed in the submitted article are our own
and not an official position of the institution or funder.
Source(s) of support
South African National Biodiversity Institute, South Af-
rican Environmental Observation Network, National
Research Foundation.
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... Not only do cities grow outwards and interact with their surroundings, the urban environment itself is in constant change. Species meet and interact in new ways, forming novel and changeable urban assemblages (Hobbs et al. 2006;Kowarik 2011), climate change is exacerbated by the urban heat island effect, soils are constantly disturbed (Muller et al. 2021), green infrastructure is meshed with buildings and transportation infrastructure and water is rerouted and quite often polluted (Koekemoer et al. 2021). Land conversion and construction of transportation infrastructure or housing may be the most obvious land-use change, but people's actual use and stewardship of land (management practices, recreational uses, preferences for plants or other organisms etc.) will have additional, more subtle but still profound implications (Andersson et al. 2007). ...
... Kellner et al. 2021), and assessments of the status and trends of biodiversity as well as environmental quality (e.g. Berner et al. 2021;Muller et al. 2021, Shikwambaba et al. 2021. Knowing the causes and likely consequences of change will become increasingly vital as we move into a future characterised by uncertainty and change. ...
... Traits which determine how organisms respond to change are a powerful tool for understanding some of the dimensions of ecological resilience (see e.g. Muller et al. 2021;Van Coller et al. 2021). When combined with traits describing the influence the organisms have on their environment, this approach can provide a baseline for starting to think about the resilience of the functions that in turn support ecosystem services. ...
... Plant families that comprised most of the frequent taxa during the drought included Acanthaceae and Amaranthaceae in the nutrient-rich site, and Fabaceae and Boraginaceae in the nutrient-poor site ( Table 1). Prevalence of the Fabaceae is in accordance with Wagner et al. (2016) who reported that nitrogen-fixing herbaceous legumes from the Fabaceae may increase in abundance after disturbances in dry savanna rangelands, and also in disturbed grasslands (Muller et al. 2021). Nitrogen-fixing ability is a trait generally associated with ecosystems with low nutrient availability (Cornelissen et al. 2003), explaining the high frequency of Chamaecrista mimosoides (L.) Greene in the nutrient-poor site (Table 1). ...
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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 drought-tolerant species with their related functional traits. Results: Drought-tolerant forb flora comprised of several plant families and species with overlapping traits, of which the ability to resprout was related to perennials , whereas succulence and prostrate growth form were typical annual forb dominance traits. Conclusion: Results highlight the functional importance of forbs and their resilience to drought events in protected areas.
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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 of the herbaceous layer in savanna ecosystems and valued for the ecosystem services and functions they provide, they have not been the primary focus in most savanna vegetation studies. We performed a systematic review of scientific literature to establish the extent to which forbs are implicitly or explicitly considered as a discrete vegetation component in savanna research. The overall aims were to summarize knowledge on forb ecology, identify knowledge gaps, and derive new perspectives for savanna research and management with a special focus on arid and semiarid ecosystems in Africa. We synthesize and discuss our findings in the context of different overarching research themes: (a) functional organization and spatial patterning, (b) land degradation and range management, (c) conservation and reserve management, (d) resource use and forage patterning, and (e) germination and recruitment. Our results revealed biases in published research with respect to study origin (country coverage in Africa), climate (more semiarid than arid systems), spatial scale (more local than landscape scale), the level at which responses or resource potential was analyzed (primarily plant functional groups rather than species), and the focus on interactions between life forms (rather seldom between forbs and grasses and/or trees). We conclude that the understanding of African savanna community responses to drivers of global environmental change requires knowledge beyond interactions between trees and grasses only and beyond the plant functional group level. Despite multifaceted evidence of our current understanding of forbs in dry savannas, there appear to be knowledge gaps, specifically in linking drivers of environmental change to forb community responses. We therefore propose that more attention be given to forbs as an additional ecologically important plant life form in the conventional tree–grass paradigm of savannas. Through this systematic review on forb ecology, we evaluate and summarize current knowledge of forbs in dry African savanna ecosystems and conclude that the ecological understanding of savanna community responses to drivers of global environmental change requires knowledge beyond the plant functional group level. Here, we highlight important findings and summarize knowledge gaps and future perspectives for including forbs as an additional ecologically important plant life form in the conventional tree–grass paradigm of savannas.
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Extensively managed grasslands are recognized globally for their high biodiversity and their social and cultural values. However, their capacity to deliver multiple ecosystem services (ES) as parts of agricultural systems is surprisingly understudied compared to other production systems. We undertook a comprehensive overview of ES provided by natural and semi‐natural grasslands, using southern Africa (SA) and northwest Europe as case studies, respectively. We show that these grasslands can supply additional non‐agricultural services, such as water supply and flow regulation, carbon storage, erosion control, climate mitigation, pollination, and cultural ES. While demand for ecosystems services seems to balance supply in natural grasslands of SA, the smaller areas of semi‐natural grasslands in Europe appear to not meet the demand for many services. We identified three bundles of related ES from grasslands: water ES including fodder production, cultural ES connected to livestock production, and population‐based regulating services (e.g., pollination and biological control), which also linked to biodiversity. Greenhouse gas emission mitigation seemed unrelated to the three bundles. The similarities among the bundles in SA and northwestern Europe suggest that there are generalities in ES relations among natural and semi‐natural grassland areas. We assessed trade‐offs and synergies among services in relation to management practices and found that although some trade‐offs are inevitable, appropriate management may create synergies and avoid trade‐offs among many services. We argue that ecosystem service and food security research and policy should give higher priority to how grasslands can be managed for fodder and meat production alongside other ES. By integrating grasslands into agricultural production systems and land‐use decisions locally and regionally, their potential to contribute to functional landscapes and to food security and sustainable livelihoods can be greatly enhanced.
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The indelible imprint of humanity is credited for the major degradation of natural systems worldwide. Nowhere are the transforming qualities of mankind more apparent than in the native temperate grassland regions of the world. Formerly occupying some 9 million km², or 8% of the planet’s terrestrial surface, native temperate grasslands have been reduced to vestiges of their former glory. Only 4.6% are conserved globally within protected areas—a testament to being the least protected and the most extensively transformed of the world’s terrestrial biomes. The aim of this paper is to continue promoting the conservation value of native temperate grasslands, and reiterate the need for further protection and sustainable management before further losses and inadequate protection undermine ecological integrity any further. A new strategic direction is presented for the next decade, underpinned by ten key focus areas. The most realistic opportunities to improve protection lie in central, eastern and western Asia where landscape-scale tracts of native temperate grassland remain in reasonable condition. Such a course necessitates a strong reliance on integrating sustainable use and conservation by promoting concepts such as Indigenous and Community Conserved Areas as legitimate and recognized forms of protected areas. Here the conservation value of working rangeland landscapes utilised by nomadic pastoralists comes to the fore. The naive and short-sighted approach to viewing native temperate grasslands merely as a palette for transformation and intensive utilisation should be weighed more objectively against an understanding of the myriad benefits they provide.
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Natural grasslands deliver essential ecosystem services through plant production, which enhances water supply, nutrient cycling, soil retention and greenhouse gas mitigation. Although the condition of montane grasslands for provision of ecosystem services is maintained by regular annual or biennial burning, controversy exists over the impact of different frequencies and seasons of burning on grassland productivity. The objective of this study was to determine the long-term effects of different burning regimes on primary production and quality of the montane grasslands of the KwaZulu-Natal Drakensberg. There were no significant differences in the mean standing live mass between 30 years of annual winter and biennial spring burning. However, in unburnt areas productivity was 20% lower (118.2 g m−2) than in regularly burnt grassland (144.7–154.5 g m−2). Crude protein did not vary between the annual winter and biennial spring treatments (95–113 kg ha−1), but was significantly lower in unburned areas (45 kg ha−1). However, an infrequent fire in a protected area caused a temporary spike in crude protein (16%) compared with regular burning (5–10%), which can benefit wildlife. We conclude that montane grasslands can be burnt annually or biennially in the dormant season to promote long-term productivity.
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Is it possible to construct indicator values that would place individual species on gradients of disturbance frequency and severity? We suggest that such indicator values could be defined on the basis of the disturbance regimes under which individual species occur, to be independent of their traits. They should also separate disturbance frequency from disturbance severity. Czech Republic. We used a stratified set of 30 115 vegetation-plot records sampled over the whole country and classified into 39 phytosociological vegetation classes. Each class was assigned values of disturbance frequency and severity by expert judgement. A Disturbance Frequency Index for each species was calculated as the mean of the common logarithm of the disturbance frequency of all vegetation classes weighted by occurrence frequencies of this species in those classes. A Disturbance Severity Index was defined as mean disturbance severity of all vegetation classes weighted by occurrence frequencies of this species in those classes. For forest vegetation, indices were computed separately for the whole community and for the herb layer, which experiences different types of disturbance. Further, we constructed a disturbance index from vegetation structural parameters, viz. summed covers and community-weighted mean of height at maturity of species recorded in each plot for each vegetation class. We assessed all indices by comparing their values with data on functional traits of the species. We calculated values of the indices for 1248 species. The Disturbance Frequency Index and Disturbance Severity Index were correlated, but still described different responses of individual species to disturbance. The index based on vegetation structure was correlated mainly with the Disturbance Frequency Index. All indices showed strong relationships to plant traits: species with high values of all disturbance indices tended to have small seeds, to be annual and non-clonal or able to spread clonally over large distances. Constructing species disturbance indices based on vegetation characteristics, not plant traits, is feasible and provides meaningful scores. A similar approach can be used in any region where sufficient vegetation data are available. Disturbance indices can be used to address a number of questions in plant evolution and community or landscape ecology.
Mesic grasslands in South Africa harbour a diverse community of herbaceous perennial forb species that outnumber grass species by up to 5-6:1, provide various ecosystem services as well as forage for livestock, and are sensitive to overgrazing. However, despite their prevalence and ecological importance, the potential of forb species as grazing indicators has not been evaluated nor are they routinely included in grassland condition assessments. We aimed, therefore, to identify a subset of potential grazing indicator forb species that had a consistent response to a range of grazing intensities historically applied at sites in two mesic grasslands, Midlands Mistbelt grassland (n = 123) and KwaZulu-Natal Sandstone Sourveld grassland (n = 55). Canonical correspondence analysis was used to assess forb composition changes in response to an ordinal index of grazing intensity to identify the most responsive abundant forbs in each grassland. Most (88-92%) forbs had a neutral or inconsistent response to grazing but 24 and 32 species in Mistbelt and Sandstone grassland, respectively, were sufficiently abundant and responsive to be considered potential key grazing indicators. Alternative, somewhat less reliable indicator species were also identified. Grazing-sensitive indicator forbs that declined under grazing (Decreaser species) mostly were erect with elevated growing points whereas grazing-resistant species (Increasers) were predominantly prostrate species. A weighted sum of the abundance of indicators and their grazing sensitivity weights based on the relative position of their centroids along the grazing gradient provides an index (1-100), the forb condition score (FCS), of the overall impact of grazing on the forbs at a site, with high FCS indicating minimal impact. The FCS adequately predicts overall indigenous forb species richness (square-root transformed) in both Mistbelt (r 2 = 0.657) and Sandstone grassland (r 2 = 0.795). The key grazing indicator forbs identified in our study could be used together with other assessment methods of grass condition and cover for rapid and cost-effective assessment and monitoring of the impact of grazing on the integrity of mesic grassland. Further testing and refinement of the proposed grazing indicator forbs and the FCS index is, however, required.
Intensive, large-scale cultivation of food crops has led to major biodiversity loss worldwide due to fragmentation and degradation of remnant semi-natural habitat within agro-ecosystems. The response of vegetation to these disturbances is often measured in terms of taxonomic diversity loss. However, some plant groups may have more pronounced negative reactions to agricultural disturbance than others, which may not necessarily be expressed in the overall species diversity of the community. It is now widely accepted that the responses of plant taxa to environmental disturbances may bemore directly linked to characteristics or traits that enable or hinder their persistence in disturbed environments. This highlights the need to assess the impacts of agricultural disturbance on the abundance patterns and diversity of specific plant traits and functional types. Maize agriculture is a common land-use feature in the grassy biomes of South Africa, but the effect that crop production has on surrounding semi-natural vegetation is still relatively unknown. In this study, we describe the specific functional trait patterns of plant communities associated with maize agro-ecosystems in six localities situated within the Grassland and Savanna biomes of South Africa. Although functional diversity was severely decreased in maize fields, marginal vegetation (30–100m from crop field edges) displayed no indication of functional diversity loss ormajor changes in trait composition. Chamaephytic and hemicryptophytic (perennial) life forms, nitrogen-fixing ability and spinescence were trait attributes that were most frequently found in semi-natural vegetation but were lost in the crop field environment. Inside the maize fields, these trait attributes were replaced by annual, low-growing individuals with clonal parts and long-range dispersal mechanisms that can establish in the ephemeral crop field environment. Observed patterns were different for grassland and savanna maize fields, indicating that maize fields situated in the Grassland and Savanna biomes favoured different plant trait assemblages.
BACKGROUND: Grasslands are heavily utilised for livestock agriculture and the resultant degradation through mismanagement contributes to an estimated 60% of this biome being permanently transformed. This study focused on the impact of fire and grazing in moist highland grasslands OBJECTIVES: To determine the contribution of burning frequency and grazing intensity combined (for domestic livestock and indigenous ungulates) on vegetation structure heterogeneity and species diversity METHODS: Eight study sites under different management regimes were sampled over two summers. Vegetation structure characteristics and diversity data were collected monthly within multiple replicates in each study site. A disc pasture meter was used to assess standing biomass. Differences in vegetation structure characteristics, plant community composition and plant species assemblage structure across sites were statistically analysed using analyses of variance, indicator species analyses, multidimensional scaling ordinations and two-way cluster analyses RESULTS: The combination of heavy grazing and annual burning leads to a distinct plant community dominated by disturbance specialist species. Selective grazing by indigenous herbivores promotes a community of unpalatable species. This study illustrates that fenced indigenous herbivores, even at moderate stocking densities, have a greater detrimental impact on plant diversity and structure than do domestic livestock CONCLUSION: Intensive grazing and burning have a detrimental impact on plant species diversity and structure. This also affects resultant palatability for grazing livestock and fenced game. To promote both grazing quality and ecological integrity we recommend a minimum sustainable 'fodder capacity' or standing phytomass of 5000 kg per large-animal unit per hectare for domestic livestock in moist highland grasslands.
Concerns over deforestation have led to attempts to identify suitable areas for reforestation around the world ( 1 ). The most ambitious effort to date is the World Resources Institute (WRI) Atlas of Forest and Landscape Restoration Opportunities ( 1 ). This map is linked to a global plan to reforest degraded lands to offset anthropogenic CO2 emissions. The immediate target is the reforestation of 1.5 million km2 by 2020 ( 2 , 3 ). Vast areas of open grassy vegetation have been identified as suitable for reforestation. But are all these grasslands secondary products of deforestations? Recent research shows that grasslands are often ancient and highly biodiverse, but it remains difficult to distinguish between primary and secondary grasslands on a large scale. Reforestation efforts thus risk converting ancient tropical grasslands to plantations.