Near extinction?

Can the pi under ofquiver trees becontrolled?

An insatiable market for theNorthern Cape's Aloe dichotmacould be tipping the scalestowards its exti nction

by Eisabe Powell, Scientific Services, Department of Tourism, Environment and Conservation, Kimberley

The lollypop silhouettes of Aloe dichotoma, the quiver tree

or kokerboom, are an integral part of the Northern Cape

landscape. Unfortunately their architectural beauty and

low water requirements have not escaped the prying eyes of

landscapers and flora traders who now concentrate on this

species to such an extent that the long-term sustainability of

the species is in jeopardy. Drought-stricken farmers collect

Aloe dichotoma specimens from their farms and sell them in

order to keep their farms going. In fact, some farmers remove

Aloe dichotoma populations to 'improve' their grazing, thus

increasing the pressure on the wild Aloe dichotoma popula­

tions.The Directorate of Conservation and Environment (DTEC)

in the Northern Cape have investigated the situation to deter­

mine whether the exploitation of Aloe dichotoma in its natural

state is feasible, and if so, what measures need to be put into

place to ensure sustainable utilisation.

A natural historyThe genus Aloe belongs to the family Asphodelaceae (for­

merly Liliaceae). Aloe dichotoma is a perennial tree succulent

that can grow 3-9 m high, but has been known to reach

heights of 12 m. When it gets to 2 m or 3 m high, the plant

starts to dichotomously branch into several branches. These

branches, together with the leaves that are borne in terminal

rosettes, give the tree its lollypop appearance.

Flowering time is from June to August, when bright fleshy

yellow flowers are borne on short and erect inflorescences. The

flowers produce a lot of nectar, which is a valuable source of

food to various birds and bees, thus playing the role of polli-

CLIMATE CHANGE

Modelling work by The Climate Change ResearchGroup at the South African National BiodiversityInstitute suggests that species and ecosystemsin the western parts of southern Africa would beaffected the most by climate change. We wonderedif early impacts of climate change might already beapparent in these regions, and Wendy Faden, oneof our M.Sc. students, attempted to relate signsof long term increases in water deficits in northernNamaqualand and southern Namibia to patterns ofadult mortality in populations of Aloe dichotoma.The kokerboom is the ideal species for this work, asit has ahuge geographic range, a long lifespan, anddead individuals remain standing for many yearsafter they succumb, providing ahistory of mortality.Wendy's substantial'and award-winning study hasconfirmed that declining populations can be relatedto deteriorating climatic conditions. While climatechange is not likely to cause the extinction of thisspecies in the next 100 years, Wendy's work showsthe value of protecting this species from additionalhuman caused stresses.Guy FMidgley, Climate Change Group, SANSI,Kirstenbosch

RIGHT: Long-lived species like Aloe dichotoma are atthe mercy of variable climatic events - and vandalism.Photo: E. Powell.

70 June 2005 Veld&Flora

ABOVE: The lollypop silhouettes of Aloe dichotoma, the Quiver tree or kokerboom, are an integral part of theNorthern Cape landscape. Photo: EPowell.

nator and provider. The seeds have twoor three wings attached to them, whichsuggests that they are wind-dispersedover relatively short distances in thevicinity of the mother plant.

The growth rate of a juvenile Aloedichotoma is faster than that of anadult plant. The juvenile stage lastsfor about fifty years, whereas the adultstage lasts three times longer (up to 150years) during which time relatively fewchanges to its size and shape occur.The senescent stage takes about fiftyyears, making the average lifespan ofAloe dichotoma 250 years. Considerablevariation exists however, as the growthrate is influenced by external environ­mental factors such as soil type, cli­mate, diseases and grazing pressure.

Long-lived species like Aloe dichotomaare at the mercy of variable climaticevents. Aloe dichotoma seedlings need todevelop sufficient water storage capac­ity as soon as possible to enable themto survive the cyclical dry periods. Thismeans that seedling survival requiresa series of favourable climatic events,a suitable microhabitat and protectionagainst predation and competition. Italso means that they are greatly influ­enced by drought.

Distribution and conservationAloe dichotoma is restricted to the drier

western parts of Namibia and SouthAfrica. In South Africa it occurs predom­inantly in the Northern Cape, with a fewgrowing in the Western Cape. It is anendemic species of the Succulent Karooand Nama Karoo biomes (Namaqualandand Bushmanland regions).

Aloe dichotoma is an extremely oppor­tunistic species and it occurs in avariety of habitats - ranging from rockyarid mountain areas to flat sandy plainson different soil types, and in differentclimates - from winter, bimodal, as wellas summer rainfall areas as long asthey are low rainfall regions. Within thisarray of habitats and climates, you willfind Aloe dichotoma either as an isolat­ed individual or in dense stands, calledquiver tree forests, for example thefamous 'forest' just south of Kenhardt.

Aloe dichotoma is protected in theNorthern Cape under the EnvironmentalConservation Ordinance No. 19 of 1974.According to the Ordinance, no col1ec­tion, cultivation, trade, export or importof Aloe dichotoma is allowed withouta valid permit issued by the relevantconservation authority. It also providesfor the Director of Conservation to sub­ject licensing to conditions deemed fit

to ensure the species future survival.These conditions are then attachedto the permit being issued. Similarly,Aloe dichotoma is protected in the otherprovinces of South Africa, although itonly occurs naturally in the NorthernCape and Western Cape.

According to the international IUCNcriteria for species conservation statusassessments, Alpe dichotoma is notthreatened at this stage. However, itis listed as an Appendices II speciesin CITES (Convention on InternationalTrade in Endangered Species). CITESaddresses the international trade of aspecies and for a species to be CITESlisted, there must be concern for theimpact that trade has on naturalpopulations. In Namibia, Aloe dichoto­ma is protected under the NatureConservation Ordinance NO.4 of 1975.Permits are needed from the Ministry ofEnvironment and Tourism of Namibia tocollect, trade, grow, import and export.

As a signatory to the Global Strategyfor Plant Conservation, South Africa

has an obligation to conserve its flora tothe best of its ability. This Strategy wasadopted and approved in Decision VI/9of the sixth meeting of the Conferenceof Parties (CoP) to the Convention onBiological Diversity (CBD) in The Haguein 2002 and states that conservationauthorities have an obligation to docu­ment plant diversity, conserve it, ensurethat it is utilised sustainably and pro­mote an awareness of it.

The long term survival of Aloe dichoto­ma is threatened by drought, consump­tion by baboons, porcupines and otherrodents (possibly the dassie rat Petromystypicaus), fungal infections and aphidinfestations. Trampling, weed invasionand goat browsing in sensitive nurseryareas also impact heavily on the aloes.Recently, two factors that threaten thesustainability of the aloes were identi­fied as climate change and 'wild craftedcol1ections' (trade). Indications are thatclimate change could cause a 50%reduction of the distribution range ofAloe dichotoma in the Northern Cape

June 2005 Veld&Flora 71

by 2050. Add to this the impact ofthe 'collection' of about forty-one Aloedichotoma trees every month, and youhave a problem.

Generally Aloe dichotoma trees arebeing traded by for about R2 000 -R3

000 per metre height. The estimated'wild crafted trade' for 2004 from the

Northern Cape was R742 000. Thisis quite a good incentive for a farmerstruck by severe drought. The extentof illegal collections is not known, butindications are that it is fairly large.

Young trees and seedlings do not haveextensive root systems making it easyfor collectors to remove them from the

wild.An additional challenge facing

the Directorate of Conservation andEnvironment is whether Aloe dichotomaimpacts negatively on grazing capacity.Some farmers claim that they want toremove some of the trees to improvetheir grazing as they are 'encroach­

ing' on their farms. Although it is notscientifically proven yet, preliminarysurveys reveal that this statementis unfounded. Further research isunderway to confirm or contradict

BELOW: Aloe dichotoma is regarded as a 'keystonespecies' in the arid Karoo providing food, nest-ing and shelter sites, as well as water in times ofdrought, for a variety of animals. Photo: EPowell.

72 June 2005 Veld&Flora

preliminary findings beyond doubt.

How bleak is the future?Research indicates that rapidly chang­

ing climate patterns will cause theextinction of many plant species within

the next 100 years. Aloe dichotomamight be one of these as its mortality

rates have already increased dramati­cally and its recruitment levels havedeclined over the past few decades as a

consequence of the reduced rainfall andincreased rainfall variability caused byclimate change. Aloe dichotoma recruit­

ment is increasing in the winter rainfallregion, while it is decreasing in thesummer rainfall regions. Recent geneticstudies also indicated that the Aloedichotoma populations in the north aregenetically more diverse than those inthe south, implying that the northernpopulations are older than those in thesouth. It takes many years for a speciesto build up genetic diversity, and there­

fore the southern distribution mighthave been established more recently.Aloe dichotoma appears to be 'migrat­ing' to the south as a response to thechanging climate.

Recent research on Aloe peglerae (that

has a lifespan of sixty years) indicatedthat sustainable utilisation is not pos­sible as the sustainable quota of 0.12%(to be collected annually) was regardedas not being financially viable. The pre­

cautionary principle for Aloe dichotoma(with a lifespan of 150 years) would

thus be to not allow future collectionsfrom the wild, except for that of seed forartificial propagation. Although theseare different species, they are from thesame genus and might have similar

sensitivities toward harvesting impacts.

Going by the Aloe peglerae results, seedcan be collected sustainably if less than10% of the seeds from a population arecollected each year, making sure that

collections are distributed throughoutthe population to spread the impact.A seed collection quota that is specifi­cally for Aloe dichotoma still needs to be

determined.The main concern of the conservation

authority regarding the collection of,and trade in, Aloe dichotoma from thewild is the possible over-exploitation ofthe species, the accompanying risk ofthe erosion of the genetic quality and

diversity of the species and the collec­tive impact that wild collections andclimate change might have on the spe­cies' survival. Other factors with regardto the function and ecological role ofAloe dichotoma in its natural environ-

ment need to be considered as well. Forinstance, Aloe dichotoma is regarded as

a 'keystone species' in the arid Karoo,providing food for birds (includingmousebirds, dusky sunbirds, and pied

barbets), nesting and shelter sites forvarious birds like the pied barbet thatmakes holes in its trunk, the sociable

weavers, pygmy falcon, and redheadedfinches and other species like baboons.It is also a valuable source of water foranimals, like porcupines, in times ofdrought. Also of importance in consider­

ing the role of Aloe dichotoma is the factthat its distribution range occurs withinthe Succulent Karoo Biome, which is aninternational biodiversity hotspot.

It is a long-lived species, dependent

on sporadic environmental events likegood rainfall at crucial growing stages.This, and the fact that its seeds mightonly be viable for two years in its natu­ral environment, is cause for concern.The trade in Aloe dichotoma might be

a recurrent event in its life cycle too,as thirty years ago when a ten-year

drought was in full swing during theseventies, farmers also traded with thespecies. This trade must have ceasedat the end of the drought when farm­ers returned to their normal farming

practices.Soon a proclamation will be published

in the Government Gazette banning allAloe dichotoma collections from the wildfor an interim period. Various surveysand inspections will be conducted dur­

ing this time to enable the Directorateof Conservation and Environment todevelop a sustainable quota systemshould data indicate that sustainableutilisation is possible. Aloe dichotomaseed may presently be collected fromthe wild under permit, but no more

than 10% of a population's seed may beremoved, and collection points must bedistributed over the population's distri­bution range to conserve a representa­tive gene pool for the species. During

the interim period, the feasibility of acore conservation area will be inves­

tigated and the possibilities of imple­menting 'stewardships' and community

based natural resource managementprojects will be explored.

I urge students and researchers to

obtain more information that will helpus to conserve biodiversity, because

without help, conservation authoritieswill not be able to manage the situationproperly, and we will lose several of oureconomically valuable species.

For a list of references, please emailthe Editor at Voget@kingsley.co.za.