Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 August 2020 | 12(11): 16614–16619
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
doi: https://doi.org/10.11609/jott.5728.12.11.16614-16619
#5728 | Received 23 January 2020 | Final
received 31 July 2020 | Finally accepted 06 August 2020
Evaluating threats and
conservation status of South African Aloe
Samuel O. Bamigboye
Botany Department, School of
Mathematical and Natural Sciences, University of Venda, 0950, South Africa.
reachtoba@gmail.com
Editor: Martin Potgieter, University of
Limpopo, Sovenga, South Africa. Date
of publication: 26 August 2020 (online & print)
Citation: Bamigboye, S.O. (2020). Evaluating threats
and conservation status of South African Aloe. Journal of Threatened Taxa 12(11): 16614–16619. https://doi.org/10.11609/jott.5728.12.11.16614-16619
Copyright: © Bamigboye 2020. Creative Commons Attribution 4.0
International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: None.
Competing
interests: The author declares no competing
interests.
Abstract: South Africa is one of
the biodiversity hotspots for Aloe in Africa. This makes it important to evaluate the
conservation status and threats to this genus.
The South African National Biodiversity Institute (SANBI) Red List was
employed to evaluate these two factors.
Results revealed that 44% of all species in this genus are of
conservation concern with the majority of them facing threats. This study recommends that more attention
such as strengthening the protection of these species and controlling the
threats identified in this study should be given to species in this genus in
terms of conservation management to reduce their risk of extinction.
Keywords: Asphodelaceae,
biodiversity loss, extinction risk, hotspot, threatened species.
The genus Aloe belongs to
the Asphodelaceae family (Cousins &
Witkowski 2012). Biodiversity hotspots
for this genus in Africa are located in Ethiopia, Madagascar and southern
Africa (Grace 2009), which coincide with
Africa’s main biodiversity hotspots (Daru et al. 2013).
Aloes are important to any ecosystems where they are
found (Cousins & Witkowski 2012).
Their nectar is a source of food for many insects (Nicolson & Nepi 2005; Botes et al. 2009a,b)
and avians (Symes et al.
2008; Forbes et al. 2009). They also
modulate harsh environmental conditions, which facilitate colonization of the
environment by other plant taxa (Wabuyele & Kyalo 2008). Their
mat-like root that is dense assist in preventing soil erosion (Smith & Van Wyk 2009).
Some species of this genus are traded commercially as
cosmetics (Grace et al. 2015) and medicine (Bjorå et
al. 2015). This has led Aloe to
become threatened, with the majority of species in this genus being included in
the Convention on International Trade in Endangered Species of Wild
Fauna and Flora (CITES) (Grace 2011). This implies that conservation of the species
in this genus should be given a high priority, especially in areas that are
hotspots of this genus (Klopper & Smith 2013).
This study evaluated the conservation status and
threats of Aloe in South Africa to determine which species in this genus
are threatened, and to determine factors responsible for their risk of
extinction. Unlike some previous studies
that mentioned the overall conservation status of the genus Aloe (e.g.,
Grace et al. 2009; Cousins & Witkowski 2012), this study showed the
conservation status and threats each species of Aloe is facing using the
South African National Red List, and also quantified in percentages species in
this genus under different Red List categories and threat categories.
Methods
This study used the SANBI Red List 2017 version to
evaluate threats and conservation status of South African Aloe. The
following percentages were calculated:
the species that are highly threatened, threatened and of conservation
concern (Critically Endangered, Endangered, Vulnerable, Near Threatened, Rare,
and Data Deficient); Aloe species that fall under different categories
of threats (Habitat destruction, individual’s collection, invasive species
occurrence, fire occurrence, overgrazing, and insect attack); species endemic
and non-endemic to South Africa; threatened endemic species; and endemic
species that are of conservation concern and different categories of threats
(habitat destruction, individual’s collection, invasive species occurrence,
fire occurrence, overgrazing, and insect attack) to endemic species.
Results and Discussion
Endemic and non-endemic species of the genus Aloe
in South Africa
A total of 125 taxa belonging to the genus Aloe
were listed in the South African National Red List; 61.6% of species in the
genus Aloe found in the South African National Red List are endemic,
while 38.4% are non-endemic. Species
endemism is an important factor to be considered in conservation because the
loss of endemic species is of high significant impact in biodiversity loss in
any geographic areas that they occur (Moraswi et al.
2019). A population survey of endemic
taxa should be encouraged to determine their population size, density, and
distribution in order to reveal their current population trend. This information will inform appropriate
conservation measures, which are adaptive to local conditions.
Highly threatened, threatened, and species of
conservation concern in South African Aloe
The various threat status categories of South African Aloe
are: 52.8% (Least Concern), 10.4% (Rare), 2.4% (Data Deficient), 3.2% (Data
Deficient, taxonomically problematic), 10.4% (Near Threatened), 11.2%
(Vulnerable), 4% (Endangered), 5.6% (Critically Endangered), 44% are of
conservation concern (Critically Endangered, Endangered, Vulnerable, Near
Threatened, Rare, and Data Deficient).
Species that are highly threatened are referred to as Critically
Endangered (Williams et al. 2013) because they are at the brink of extinction. Aloe species in this study that falls
into this category (Table 1) should be given quick conservation intervention
such as preventing further collection by people, minimizing habitat loss, and
improving on their regeneration potentials to prevent complete extirpation of
their populations. Some plant species
are not threatened, but can be flagged and given priority in terms of
conservation, and thus be referred to as species of conservation concern
(Victor & Keith 2004). Species of
conservation concern in this study that are not threatened should be monitored
to determine if they have become threatened (Table 1). For instance Data deficient taxa could
possibly be threatened (Moraswi et al. 2019). This is why further efforts is required to
obtain sufficient information about them in order to determine if they are
threatened or not.
Threats to South African endemic and non-endemic Aloe
species
Percentages of taxa in the genus Aloe in South
Africa facing different types of threats are as follows: 41.6% are threatened
by habitat destruction, 16.8% are threatened due to individual’s collection,
14.4% threatened by occurrence of invasive species, 5.6% are threatened because
of fire occurrences, 11.2% are threatened by overgrazing, 0.8% threatened due
to insect attack, while there are no threats found for 42.4% of the taxa. Aloe species are generally threatened
by habitat destruction and collection by people (Klooper
et al. 2009), a situation also reflected in this study. The collection by people are majorly due to
medicinal uses and horticultural uses which might be affecting the wild
population of these taxa (Grace 2011).
Enforcement of regulation restricting the collections of these taxa
should be more encouraged. It must be
noted that a thorough assessment of those species for which their threats are
unknown can significantly change the results pattern in the threat categories
as presented above.
Threats to endemic species of South African Aloe
The results of the percentages of endemic species of
South African Aloe facing different kind of threats are as follows: 57%
are affected by habitat destruction, 23.4% affected by Individual’s collection,
17% are affected by invasive species, 9% by fire occurrence, 13% by
overgrazing, while there are no threats found for 26% of the endemic species. Habitat destruction and collection by people
still stood out among the threats to endemic South African Aloe
species. It is recommended that species
for whom their threats are not known (Table 1) be further assessed. Thus, it is possible that a reassessment of
these species can alter the results presented above.
Conservation status of endemic species in South
African Aloe
The results of the percentages of endemic Aloe
taxa in South Africa on SANBI Red List threat status categories are as follows:
32.4% (Least Concern), 5.2% (Data Deficient taxonomically problematic), 2.6%
(Data Deficient), 15.6% (Rare), 15.5% (Near Threatened), 14.3% (Vulnerable),
5.2% (Endangered) and 9.1% (Critically Endangered); 28.6% of the endemic
species in this genus are threatened (Critically Endangered, Endangered,
Vulnerable); 62.3% of the endemic species are of conservation concern
(Critically Endangered, Endangered, Vulnerable, Near Threatened, Rare, and Data
Deficient). Endemic plant species are
more vulnerable to extinction (Williams et al. 2013) because they are
restricted to certain geographic regions and the total extirpation of their
populations in that region automatically result in total extinction of the
species (Bamigboye 2019). This is also being clearly revealed in this
study as all the Critically Endangered Aloe species in this study are
endemic species, which further supports the notion that a more proactive
conservation intervention should be given to these species.
Conclusion
This study presents the current conservation status,
endemic status and threats that each species of Aloe in South African
Red List are facing. It also quantifies
the percentages of species in this genus that fall into different SANBI Red
List categories, threat categories, and endemism categories. This study provides information on the
species of Aloe in South Africa that need more conservation
attention. For instance the Critically
Endangered species in this study that are all endemic species (Table 1) can be
given higher priorities for conservation.
Conservation status of species changes over time (Bamigboye
et al. 2016). It is recommended that
South African Aloe should be further evaluated to see if they have
become more threatened in recent times or not.
A recent evaluation will also reveal if the ones that are not threatened
on SANBI Red List are now threatened.
Table 1. List of Aloe species in South Africa,
their SANBI Red List Status, their endemism status and their threats on SANBI
Red List.
|
Species |
SANBI Red List
status |
Endemism status |
Threats |
|
Aloe aculeata Pole-Evans |
Least Concern |
Not endemic |
No threat |
|
Aloe affinis A.Berger |
Least Concern |
Not endemic |
Habitat destruction |
|
Aloe africana Mill. |
Least Concern |
Endemic |
Habitat destruction |
|
Aloe albida (Stapf)
Reynolds |
Near Threatened |
Not endemic |
Habitat destruction |
|
Aloe alooides (Bolus) Druten |
Least Concern |
Endemic |
Habitat destruction |
|
Aloe ammophila Reynolds |
Least Concern |
Endemic |
No threat |
|
Aloe angelica Pole-Evans |
Least Concern |
Endemic |
Habitat destruction |
|
Aloe arborescens Mill. |
Least Concern |
Not endemic |
No threat |
|
Aloe arenicola Reynolds |
Near Threatened |
Endemic |
No threat |
|
Aloe barbara-jeppeae T.A.McCoy
& Lavranos |
Near Threatened |
Endemic |
Habitat destruction |
|
Aloe bergeriana (Dinter) Boatwr. & J.C.Manning |
Data Deficient |
Not endemic |
Habitat destruction |
|
Aloe bowiea Schult. &
J.H.Schult. |
Critically Endangered |
Endemic |
Habitat destruction |
|
Aloe braamvanwykii Gideon F.Sm.
& Figueiredo |
Endangered |
Endemic |
Habitat destruction |
|
Aloe branddraaiensis Groenew. |
Least Concern |
Endemic |
Habitat destruction |
|
Aloe brevifolia Mill. var. brevifolia |
Vulnerable |
Endemic |
Habitat destruction, invasive presence, individual’s
collection |
|
Aloe brevifolia Mill. var. depressa
(Haw.) Baker |
Data Deficient taxonomically problematic |
Endemic |
Habitat destruction |
|
Aloe broomii Schönland
var. broomii |
Least Concern |
Not Endemic |
No threat |
|
Aloe broomii Schönland
var. tarkaensis Reynolds |
Rare |
Endemic |
No threat |
|
Aloe buhrii Lavranos |
Vulnerable |
Endemic |
Individual’s collection, habitat destruction |
|
Aloe castanea Schönland |
Least Concern |
Endemic |
No threat |
|
Aloe chabaudii Schönland
var. chabaudii |
Least Concern |
Not endemic |
No threat |
|
Aloe challisii Van Jaarsv.
& A.E.van Wyk |
Vulnerable |
Endemic |
Individual’s collection, invasive presence |
|
Aloe chlorantha Lavranos |
Vulnerable |
Endemic |
Insect attack |
|
Aloe chortolirioides A.Berger var.
chortolirioides |
Vulnerable |
Not endemic |
Habitat destruction, invasive presence, fire
occurrences, |
|
Aloe chortolirioides A.Berger var.
woolliana (Pole-Evans) Glen & D.S.Hardy |
Least Concern |
Endemic |
Habitat destruction, fire occurrences |
|
Aloe claviflora Burch. |
Least Concern |
Not endemic |
No threat |
|
Aloe comosa Marloth &
A.Berger |
Least Concern |
Endemic |
Individuals collection, habitat destruction |
|
Aloe condyae Van Jaarsv.
& P.Nel |
Vulnerable |
Endemic |
Invasive presence |
|
Aloe cooperi Baker |
Least Concern |
Not endemic |
Habitat destruction, overgrazing, invasive presence |
|
Aloe craibii Gideon F.Sm. |
Critically Endangered |
Endemic |
Individual’s collection, fire occurrences, invasive
presence, habitat destruction |
|
Aloe cryptopoda Baker |
Least Concern |
Not endemic |
No threat |
|
Aloe dabenorisana Van Jaarsv. |
Rare |
Endemic |
Individual’s collection |
|
Aloe dewetii Reynolds |
Least Concern |
Not endemic |
No threat |
|
Aloe dominella Reynolds |
Near Threatened |
Endemic |
Habitat destruction, overgrazing, fire occurrences,
invasive presence |
|
Aloe dyeri Schönland |
Least Concern |
Not endemic |
No threat |
|
Aloe ecklonis Salm-Dyck |
Least Concern |
Not endemic |
Habitat destruction, invasive presence |
|
Aloe excelsa A.Berger var.
excelsa |
Least Concern |
Not endemic |
No threat |
|
Aloe falcata Baker |
Least Concern |
Not endemic |
Individual’s collection, overgrazing |
|
Aloe ferox Mill. |
Least Concern |
Not endemic |
Individual’s collection, habitat destruction,
overgrazing |
|
Aloe fosteri Pillans |
Least Concern |
Endemic |
No threat |
|
Aloe fouriei D.S.Hardy
& Glen |
Data Deficient taxonomically problematic |
Endemic |
Habitat destruction, overgrazing |
|
Aloe framesii L.Bolus |
Near Threatened |
Endemic |
Habitat destruction |
|
Aloe gariepensis Pillans |
Least Concern |
Not endemic |
No threat |
|
Aloe gerstneri Reynolds |
Vulnerable |
Endemic |
Habitat destruction, Overgrazing |
|
Aloe glauca Mill. |
Least Concern |
Endemic |
No threat |
|
Aloe globuligemma Pole-Evans |
Least Concern |
Not endemic |
No threat |
|
Aloe graciliflora Groenew. |
Least Concern |
Endemic |
No threat |
|
Aloe grandidentata Salm-Dyck |
Least Concern |
Not endemic |
No threat |
|
Aloe greatheadii Schönland
var. davyana (Schönland)
Glen & D.S.Hardy |
Least Concern |
Not endemic |
No threat |
|
Aloe greatheadii Schönland
var. greatheadii |
Least Concern |
Not endemic |
No threat |
|
Aloe greenii Baker |
Least Concern |
Not endemic |
No threat |
|
Aloe hahnii Gideon F.Sm.
& R.R.Klopper |
Near Threatened |
Endemic |
Habitat destruction |
|
Aloe hardyi H.F.Glen |
Rare |
Endemic |
No threat |
|
Aloe hereroensis Engl. var. hereroensis |
Least Concern |
Not endemic |
No threat |
|
Aloe humilis (L.) Mill. |
Least Concern |
Endemic |
Habitat destruction, individual’s collection |
|
Aloe inconspicua Plowes |
Endangered |
Endemic |
Habitat destruction, overgrazing |
|
Aloe integra Reynolds |
Vulnerable |
Not endemic |
Habitat destruction, invasive presence, fire
occurrences |
|
Aloe jeppeae Klopper & Gideon F.Sm. |
Least Concern |
Endemic |
No threat |
|
Aloe kamnelii Van Jaarsv. |
Rare |
Endemic |
No threat |
|
Aloe karasbergensis Pillans |
Least Concern |
Not endemic |
No threat |
|
Aloe knersvlakensis S.J.Marais |
Rare |
Endemic |
No threat |
|
Aloe kniphofioides Baker |
Vulnerable |
Endemic |
Habitat destruction, fire occurrences |
|
Aloe komaggasensis Kritzinger
& Van Jaarsv. |
Vulnerable |
Endemic |
Individual’s collection, habitat destruction,
overgrazing |
|
Aloe komatiensis Reynolds |
Endangered |
Not endemic |
Habitat destruction, invasive presence |
|
Aloe kouebokkeveldensis Van Jaarsv.
& A.B.Low |
Rare |
Endemic |
No threat |
|
Aloe krapohliana Marloth |
Data Deficient |
Endemic |
Individual’s collection, habitat destruction,
overgrazing |
|
Aloe lettyae Reynolds |
Endangered |
Endemic |
Habitat destruction, invasive occurrence,
overgrazing, fire occurrences |
|
Aloe linearifolia A.Berger |
Near Threatened |
Endemic |
Habitat destruction, overgrazing |
|
Aloe lineata (Aiton) Haw.
var. lineata |
Least Concern |
Endemic |
Habitat destruction |
|
Aloe lineata (Aiton) Haw.
var. muirii (Marloth)
Reynolds |
Least Concern |
Endemic |
No threat |
|
Aloe littoralis Baker |
Least Concern |
Not endemic |
No threat |
|
Aloe longistyla Baker |
Data Deficient |
Endemic |
Individual’s collection, habitat destruction,
overgrazing |
|
Aloe lutescens Groenew. |
Least Concern |
Not endemic |
No threat |
|
Aloe maculata All. |
Least Concern |
Not endemic |
No threat |
|
Aloe marlothii A.Berger
subsp. marlothii |
Least Concern |
Not endemic |
No threat |
|
Aloe marlothii A.Berger
subsp. orientalis Glen & D.S.Hardy |
Least Concern |
Not endemic |
No threat |
|
Aloe melanacantha A.Berger |
Least Concern |
Not endemic |
No threat |
|
Aloe meyeri Van Jaarsv. |
Rare |
Not endemic |
No threat |
|
Aloe micracantha Haw. |
Near Threatened |
Endemic |
Habitat destruction, invasive presence |
|
Aloe microstigma Salm-Dyck |
Least Concern |
Not endemic |
No threat |
|
Aloe minima Baker |
Least Concern |
Not endemic |
Habitat destruction |
|
Aloe modesta Reynolds |
Vulnerable |
Endemic |
Habitat destruction, Invasive presence |
|
Aloe monotropa I.Verd. |
Vulnerable |
Endemic |
Individual’s collection |
|
Aloe mudenensis Reynolds |
Least Concern |
Endemic |
Habitat destruction |
|
Aloe myriacantha (Haw.) Schult.
& J.H.Schult. |
Least Concern |
Not endemic |
Invasive occurrences |
|
Aloe neilcrouchii R.R.Klopper
& Gideon F.Sm. |
Endangered |
Endemic |
Habitat destruction |
|
Aloe neilcrouchii R.R.Klopper
& Gideon F.Sm. |
Critically Endangered |
Endemic |
Habitat destruction |
|
Aloe nubigena Groenew. |
Rare |
Endemic |
Habitat destruction |
|
Aloe parvibracteata Schönland |
Least Concern |
Not endemic |
No threat |
|
Aloe pearsonii Schönland |
Vulnerable |
Not endemic |
Overgrazing |
|
Aloe peglerae Schönland |
Critically Endangered |
Endemic |
Habitat destruction, individual’s collection |
|
Aloe perfoliata L. |
Least Concern |
Endemic |
No threat |
|
Aloe petricola Pole-Evans |
Least Concern |
Endemic |
Habitat destruction |
|
Aloe petrophila Pillans |
Rare |
Endemic |
No threat |
|
Aloe pictifolia D.S.Hardy |
Rare |
Endemic |
No threat |
|
Aloe pluridens Haw. |
Least Concern |
Endemic |
No threat |
|
Aloe pratensis Baker |
Least Concern |
Not endemic |
Habitat destruction, individual’s collection |
|
Aloe pretoriensis Pole-Evans |
Least Concern |
Not endemic |
Habitat destruction |
|
Aloe prinslooi I.Verd. &
D.S.Hardy |
Near Threatened |
Endemic |
Individual’s collection and invasive presence |
|
Aloe pruinosa Reynolds |
Vulnerable |
Endemic |
Habitat destruction, individual’s collection,
invasive occurrence |
|
Aloe reitzii Reynolds var. reitzii |
Near Threatened |
Endemic |
No threat |
|
Aloe reitzii Reynolds var. vernalis
D.S.Hardy |
Critically Endangered |
Endemic |
Individual’s collection |
|
Aloe reynoldsii Letty |
Rare |
Endemic |
Individual’s collection |
|
Aloe rupestris Baker |
Least Concern |
Not endemic |
No threat |
|
Aloe saundersiae (Reynolds) Reynolds |
Critically Endangered |
Endemic |
Habitat destruction, overgrazing, fire occurrences |
|
Aloe sharoniae N.R.Crouch
& Gideon F.Sm. |
Least Concern |
Not endemic |
Habitat destruction |
|
Aloe simii Pole-Evans |
Critically Endangered |
Endemic |
Habitat destruction, Invasive presence |
|
Aloe soutpansbergensis I.Verd. |
Rare |
Endemic |
Individual’s collection |
|
Aloe speciosa Baker |
Least Concern |
Endemic |
No threat |
|
Aloe spectabilis Reynolds |
Least Concern |
Endemic |
No threat |
|
Aloe spicata L.f. |
Least Concern |
Not endemic |
No threat |
|
Aloe striata Haw. |
Least Concern |
Endemic |
No threat |
|
Aloe succotrina Lam. |
Least Concern |
Endemic |
No threat |
|
Aloe suffulta Reynolds |
Least Concern |
Not Endemic |
No threat |
|
Aloe suprafoliata Pole-Evans |
Least Concern |
Not Endemic |
No threat |
|
Aloe thompsoniae Groenew. |
Rare |
Endemic |
No threat |
|
Aloe thorncroftii Pole-Evans |
Near Threatened |
Endemic |
Habitat destruction, invasive presence |
|
Aloe thraskii Baker |
Near Threatened |
Endemic |
Habitat destruction, individual’s collection |
|
Aloe vanbalenii Pillans |
Least Concern |
Not endemic |
No threat |
|
Aloe vanrooyenii Gideon F.Sm.
& N.R.Crouch |
Least Concern |
Endemic |
No threat |
|
Aloe verecunda Pole-Evans |
Least Concern |
Endemic |
Habitat destruction |
|
Aloe vogtsii Reynolds |
Near Threatened |
Endemic |
Habitat destruction |
|
Aloe vossii Reynolds |
Data Deficient taxonomically problematic |
Endemic |
Habitat destruction, fire occurrences, Invasive
presence |
|
Aloe vryheidensis Groenew. |
Data Deficient taxonomically problematic |
Endemic |
Habitat destruction |
|
Aloe zebrina Baker |
Least Concern |
Not endemic |
No threat |
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