ORIGINAL PAPER

Model invasions and the development of national concernsover invasive introduced trees: insights from South Africanhistory

Brett M. Bennett

Received: 13 December 2012 / Accepted: 25 August 2013 / Published online: 4 December 2013

� Springer Science+Business Media Dordrecht 2013

Abstract This article examines how invasions

within a discrete geographic, cultural, and ecological

context disproportionately shaped awareness of inva-

sions in other places. Such ‘‘model invasions’’ have

been valuable for catalyzing national and international

interest in biological invasion since the 1980s.

Specifically, this article traces how scientific and

public perspectives of invasive introduced trees

evolved in South Africa during the twentieth century.

It argues that concerns about the impact of invasive

introduced trees first developed in the Mediterranean-

climate region of the southwestern Cape Province

during the 1940s and 1950s before emerging else-

where in South Africa during the 1970s and early

1980s. Though there has been a nation-wide conver-

gence in scientific and public views of invasive trees

since the 1980s, there are still stark geographic and

cultural knowledge divergences that hinder the effec-

tiveness of contemporary invasive tree management

efforts. This study suggests that geographical knowl-

edge imbalances between regions should not be

overlooked when historicizing or planning environ-

mental management schemes at national scales.

Keywords Citizen science � Environmental

history � Fynbos � South Africa � Tree invasions

Introduction

Invasive alien plants are one of South Africa’s most

pressing environmental problems. South Africa’s

Department of Water Affairs and Forestry proclaims

that invasive introduced species—non-native plants

with self-perpetuating and expanding populations—

are: ‘‘the biggest threat to the country’s biological

biodiversity’’ (dwaf.gov.za/wfw/, accessed 2 May

2013). The most studied (Musil and Macdonald

2007: 9) and ecologically significant (Henderson

2007: 220; van Wilgen et al. 2012: 31) invasive plants

in South Africa are trees and shrubs. The Department

of Water Affairs and Forestry devotes significant

funding for the Working for Water (WFW) program,

which manages invasive plants, primarily trees, such

as species of Australian Acacia and Hakea. WFW has

received approximately $432 million USD to clear

invasive plants since its origin in 1995 (McConnachie

et al. 2012: 129). Policies to control introduced trees

are frequently (and often heatedly) discussed in

newspapers, town, and environmental planning

B. M. Bennett (&)

School of Humanities and Communication Arts,

University of Western Sydney, Bankstown Campus,

Building 7, Locked Bag 1797, Penrith, NSW 2751,

Australia

e-mail: b.bennett@uws.edu.au

B. M. Bennett

Department of Historical Studies, University of Cape

Town, Private Bag, Rondebosch 7701, South Africa

123

Biol Invasions (2014) 16:499–512

DOI 10.1007/s10530-013-0601-1

meetings, and a variety of other forums (Comaroff and

Comaroff 2001; van Wilgen 2012).

The intensity of concerns over introduced invasive

trees has stimulated social scientists to study when and

why South Africans become concerned about the

impacts of invasive introduced plants, especially trees.

There is a developed literature focusing on how fears

of invasive alien plants expressed South African

nationalism in its apartheid and post-apartheid forms.

Carruthers et al. (2011: 813) suggest that ‘‘The

discourse of the ‘danger’ of introduced invasive

species in South Africa gained momentum in the late

1950s and early 1960s’’. They argue: ‘‘national-

ism…provided justification for eradicating these [i.e.

introduced Australian Acacia] species’’. Peretti (2010:

33) takes this argument one step further by linking

South African interest in biological invasions in the

1980s with ideologies of apartheid that were ‘‘con-

cerned with separating the pure from impure’’. Taking

up the thread after the end of apartheid, Comaroff and

Comaroff (2001) argue that the frenzied criticisms of

invasive introduced trees that followed the 2000 Cape

Peninsula fires were expressions of a new post-

colonial South African nationalism that sought to

naturalise the territorial boundaries of the South

African nation-state by drawing a clear line between

‘‘aliens’’—including plants and people—and ‘‘natu-

ral’’ South Africans. One of the common features of all

three analyses mentioned above is their use of

historical examples from the southwestern Cape to

make a larger point about the nation of South Africa

and nationalism as a phenomenon.

There is another body of historical literature that

suggests that the Cape was not always an accurate

reflection of wider South African identities or history.

Van Sittert (2003: 113) suggests that the rise of floral

preservationism in the southwestern Cape during the

late nineteenth and early twentieth centuries, which

included the formation of the ‘‘national’’ Kirstenbosch

Botanic Gardens in 1913, reinforced a distinctly

patrician and Anglo Cape regional identity and

culture. He argues that at ‘‘the eve of the Second

World War, identification with the indigenous Cape

flora had become a mark of class, ethnic and regional

identity for the old imperial urban, English-speaking

middle class marooned in a new nation state governed

by rural, Afrikaans republicanism’’. British-born and

trained botanists who dominated Cape botany prior to

the 1950s consistently used the rhetoric of the

‘‘nation’’ to support a specifically Cape-oriented

botanical agenda (Pooley 2010: 601). Pooley suggests

that ecologists, botanists, and foresters in the south-

western Cape were the first scientists who attempted

‘‘to preserve ‘virgin’ indigenous vegetation against

invasion by ‘alien’ interlopers’’ before the 1960s

(Pooley 2010: 605).

Two distinct approaches to the Cape’s position in

South African environmental history have thus devel-

oped: one focuses on the Cape (particularly its

southwestern and southern regions with a Mediterra-

nean-type climate). The second focuses on South

African history and nationalism through the lens of the

Cape. This article suggests that both perspectives can

be used justifiably so long as scholars explicitly

recognize that both regions and national identities and

histories existed simultaneously and did not always

causally overlap. Rather than criticizing scholars for

focusing on the Cape at the expense of other regions,

such as the Transvaal (Carruthers 2011: 263), scholars

should remember that nation-states are constructed

and not constitutive of all of their elements. Ironically,

the trend to write transnational and comparative

histories—which were meant as a way to look beyond

the nation—can reinforce the category of nation-state

and constructions of nationalism by leading scholars

to overlook important regional distinctions. A more

nuanced understanding of the nation and nationalism

taking into account regional differences is required.

Accordingly, this paper situates the Cape within the

context of twentieth-century South African history. It

demonstrates that concerns about the impact of

invasive introduced trees only developed outside of

the Cape in the 1980s, approximately 30 years after

the development of similar concerns in the Cape

Province. The formation of a national discourse on

tree invasion built on and was influenced by a

sustained movement to study and control invasive

introduced trees in the southwestern Cape Province

that began in earnest during the 1940s and 1950s.

Fears about invasive trees developed as an expression

of the desire to protect indigenous flora from destruc-

tion rather than as an extension of earlier concerns

about the economic impact of agricultural weeds and

pests. Scientific, public, and government actors

located in the greater Cape Town metropolitan area

established a coordinated program to educate the

public about the ecological threats posed by invasive

introduced trees. These anxieties reflected distinct

500 B. M. Bennett

123

regional environmental concerns and identities that

were located within the Cape and only broadly

reflected South African nationalism or identity. Res-

idents of the southwestern Cape were unique amongst

South Africans for expressing and acting on their

concerns about the ecological impact of invasive

introduced trees before the 1980s.

In spite of the considerable attention that invasive

introduced trees received in the southwestern Cape,

there was little widespread or sustained concern about

invasive introduced trees (as opposed to other types of

weeds) elsewhere in South Africa. It was only during

the 1980s and early 1990s when scientific researchers

outside of the Cape Province began to express serious

and persistent worries about the negative hydrological,

ecological, and economic impacts caused by invasive

introduced trees. Though major post-apartheid pro-

grams, such as Working for Water, originated from a

groundswell of national interest during the 1980s and

early 1990s, they were largely justified based on Cape

research and concerns. Despite considerable funding

and publicity efforts, attempts to control invasive

introduced trees outside of a Cape fynbos context have

presented numerous challenges that have been hin-

dered by the shortage of professional experts outside

of the Cape and lower levels of awareness about the

threat posed by invasive introduced trees.

This article offers two points that are signficant for

scientists, environmental managers, and social sci-

entists researching invasive species worldwide.

First, it offers an important case study explaining

how and why scientific and public perceptions of

invasive alien species developed in one of the

world’s leading centres for the study of invasive

species. This helps to explain why people became

concerned about the ecological impact of invasive

trees during the last half of the twentieth century.

Despite the growth of historical studies of percep-

tions of alien and indigenous vegetation, this specific

question remains unanswered.

Second, the article clarifies how scientific under-

standing of particular types of invasion that developed

within specific geographic, cultural, and ecological

contexts have inspired research about invasions in

other geographies and ecologies (for a broader

discussion of how science ‘‘moves’’, see Livingstone

2003). This explains how and why concerns about

invasion in one place—such as the Mediterranean-

climate Cape or other Mediterranean-climate

ecosystems—shaped national and global awareness

of invasive species. The article concludes by suggest-

ing that more attention should be focused on finding

ways to overcome geographic knowledge and power

imbalances in regions where recognitions of invasion

have more recently developed.

Tree invasions in South Africa

Environmental and colonial contexts

Much of Southern Africa is naturally tree-less or

forest-less but has environmental conditions that could

allow for the growth of trees (Richardson and Cowling

1992; Rundel et al. 2014). This is a significant factor

that has determined much of the dynamics of the

ecological history of Southern Africa since the mid

seventeenth century. With a few exceptions, southern

Africa has in the recent past been devoid of closed-

canopy forests, which today account for less than

0.3 % of South Africa’s biomes (Mucina and Ruther-

ford 2006: 37). The lack of forests that characterises

three of South Africa’s biggest ‘fire driven ecosys-

tems’—savanna (32.5 %), grassland (27.9 %), and

fynbos (6.6 %)—is caused by the prominence of

recurring fires that kill trees or tree-like vegetation

before they can grow tall enough to survive fires

(Mucina and Rutherford 2006: 32, 37). Without the

recurrence of fire, forests might have evolved in these

biomes because in many localities there is suitable

rainfall, climate, and soil types for tree growth.

Starting in 1652 with the Dutch East India

Company (VOC) settlement at Cape Town, Euro-

pean colonists imported and planted a wide variety

of introduced trees in the southwestern and southern

Cape (Pooley 2009: 11–14). For the next 150 years

settlers planted trees for aesthetic and utilitarian

reasons, such as providing windbreaks, shelter,

shade, fruit production, and wood fuel (Showers

2010: 296). The intensity and scale of tree-planting

increased dramatically throughout the nineteenth

century as a result of the expansion of European

settlement across Southern Africa, the introduction

of a greater variety of introduced tree genera and

species (especially Australian species of Acacia and

Eucalyptus), and the growing demand for timber,

forest-cover and species to stabilise soils. The first

commercial plantation of Pinus pinaster was planted

Insights from South African history 501

123

at Genadendal Valley in the Riviersonderend Moun-

tains of the southwestern Cape during the last half of

the 1820s (Showers 2010: 299). Settlers started

establishing commercial Acacia plantations in the

Midlands of Natal during the 1860s (Witt 2005:

110–4). The creation of a state forestry department in

the Cape in the early 1880s led to the formation of the

first systematic program of timber planting through-

out the Cape. Foresters experimented widely with

introduced species in arboreta and plantations (Ben-

nett 2011: 272–77). Foresters from the Cape estab-

lished forestry departments in Natal, Transvaal and

Free State during the early 1900s (Bennett 2011:

274–5). At the dawn of the twentieth century the

largest established state plantations were located in

the Cape Colony. Natal had large commercial Acacia

plantations (Witt 2005) and private growers in the

Transvaal were beginning to establish eucalyptus

plantations (Bennett 2010: 33–6). Introduced trees

were thus spread, with some unevenness, throughout

the whole of southern Africa (Richardson et al.

2003).

Prevailing ideas of late-Victorian biogeography,

hydrology, and climatology led European settlers to

see introduced trees as a necessary botanical addition

to Southern Africa’s indigenous vegetation types.

Colonial forestry advocates in all four colonies

assumed that the largely tree-less fynbos and grassland

biomes of Southern Africa were forested prior to

human habitation (Powell 2007: 869). The lack of

forest cover was used to explain why much of

Southern Africa had such variable rain patterns, high

summer temperatures, and was prone to aridity and

drought. Tree planting was therefore seen as a way to

‘‘improve’’ Southern Africa’s climate to facilitate

European settlement (Bennett 2010: 30–33). It was an

economic imperative to plant trees in order to produce

timber for growing population and the burgeoning

mining industry during the last three decades of the

nineteenth century. With these ecological and eco-

nomic imperatives interlinked, forestry enthusiasts

believed that the sub-continent should be clothed with

forests.

These attitudes, combined with late-Victorian ideas

of natural selection, led some colonial foresters to

view self-propagating introduced tree populations as

positive and unstoppable processes. In 1902, David E.

Hutchins approved of an example where ‘‘the Cluster-

pine has spread, self-sown, up the rocky face of the

mountain, and into the rugged Genadendal valley’’

because it created a ‘‘picturesque’’ appearance (Hutch-

ins 1904: 1). Hutchins believed that introduced trees

(North American, Eurasian, and Australian) would

eventually colonize much of the Cape flora because

trees from the Northern Hemisphere and Australia

were younger, more aggressive and fitter than the Cape

flora (Bennett 2011: 269). This belief was based on

Alfred Russell Wallace’s widely cited biogeographic

argument that the Cape flora1 (e.g. what is today

classified as fynbos) was ‘‘comparatively impotent and

weak’’ (Wallace 1880: 495) when compared to more

aggressive Northern Hemisphere and Australian

floras.

Studying and conserving fynbos

The late-Victorian belief that the Cape flora was

‘‘comparatively impotent and weak’’ also influenced

the rise of an indigenous flora preservation movement

in the southwestern Mediterranean-climate region of

the Cape Colony. Fears that individual species as well

as the Cape flora could become extinct played a key

role in mobilizing floral preservation efforts during the

early twentieth century. These two concerns preceded

worries about the impact of invasive introduced trees.

Biogeographical studies of the southwestern Cape’s

flora completed during the 1880s and 1890s by the

amateur botanists Harry Bolus and Rudolph Marloth

broadly confirmed Wallace’s theory that the Cape

flora was ‘‘ancient,’’ ‘‘weak,’’ and vulnerable to

destruction by people, plants, and floras (Van Sittert

2003: 116–7). They warned that many species that

botanists had collected as recently as the late-eigh-

teenth and early-nineteenth centuries might have

already gone extinct as a result of human activities.

They specifically singled out flower pickers as key

drivers of extinction (Van Sittert 2003: 119–20). The

Mountain Club of South Africa (MCSA) was estab-

lished in Cape Town in 1891 partly to encourage

people to see flowers in situ on Table Mountain rather

than buying them at the Adderley Street flower market

for display at home (Van Sittert 2003: 118). From its

origin, the MCSA was a vehicle of citizen science

1 This paper often uses the term fynbos, but prior to the 1960s

and 1970s it was more frequently called the ‘‘Cape flora.’’

Botanists believed that the Cape flora included renosterveld and

fynbos but not succulent Karoo or forest thickets.

502 B. M. Bennett

123

(Miller-Rushing et al. 2012): its members included

leading amateur botanists (Marloth), and the Club

catalyzed regular citizens to document the botanical

geography of the Cape, collect specimens and lobby

for the preservation of the Cape flora. The MCSA’s

foundations were, like other Cape-based ‘‘national’’

South African institutions (such as the national botanic

garden established at Kirstenbosch), tied intimately

within an Anglo-imperial, Cape Fold Mountain, and

fynbos—rather than wider Southern African—context

(Van Sittert 2003: 119–20).

As a result of lobbying by botanists and Mountain

Club members, the Cape Colony’s Parliament imple-

mented the colony’s (and Southern Africa’s) first

wildflower preservation legislation, the Wildflower

Protection Act of 1905, which mandated the preser-

vation of listed indigenous species and banned flower

picking on crown land. Though the law was at first

considered to be un-successful, at the response of the

citizen-led Wild Flower Protection Committee (cre-

ated in 1912), elected provincial governments

amended the law to make it more restrictive and

punitive (Van Sittert 2003: 124). By the second half of

the century Cape-based indigenous floral preserva-

tionists viewed it as a successful legal intervention. In

1960 the Department of Nature Conservation in the

Cape Province praised the success of the Wildflower

Protection Act because: ‘‘Indiscriminate flower pick-

ing for commercial purposes was an important factor

contributing to the disappearance of our Flora, but this

practice has now been largely checked’’ (Department

of Nature Conservation of the Cape of Good Hope

1960: 11).

Botanists were equally troubled by the perceived

expansion of the drier Karoo flora, which they

believed was slowly colonizing fynbos. This theory

was also justified by Victorian biogeographic ideas:

fynbos was seen to be ancient and weaker than the

supposedly youthful and more vigorous Karoo (Van

Sittert 2003: 116–7). The fear that the Karoo was

expanding (Hoffman et al. 1995: 159–61) remained an

important theme in South African botanical and

agricultural debates throughout the twentieth century.

Concern about the southwestwardly advance of

Karoo recurred in Cape botanical discourse until the

1950s when Margaret Levyns quelled fears by

declaring in her presidential speech to the botanical

section at the 1952 South African Association for the

Advancement of Science that fynbos was safe from

destruction from invading floras: ‘‘the sad picture of

the Cape flora being slowly but surely pushed off the

African continent by the aggressive tactics of newer

and more drought-resistance floras pushing down on it

from the north is far from accurate’’ (Levyns 1952:

163). Levyns’ also challenged the ‘‘ancient’’ Cape

flora thesis, which underpinned pessimistic fears, by

showing its more ‘‘recent’’ evolution as a result of the

establishment of the Benguela current and the subse-

quence drying and cooling of the southwestern Cape

(Levyns 1962). Concerns about the expansion of the

Karoo declined in importance partly as a result of

Levyns’ research, which paved the way for modern

theories of the origins of the Cape flora.

Though public and scientific apprehensions about

flower picking and the expanding Karoo abated in the

southwestern Cape during the second half of the

twentieth century, many white Cape residents sought to

protect the Cape’s flora against threats, be they people

or plants. This vigilance was supported by a motivated

group of amateur bushwalkers and conservationists

who had already been taught to believe that fynbos was

fragile and required human protection. The strong

cultural connections that people in the southwestern

Cape formed with indigenous plants, and pre-existing

concerns about extinction, shaped concerns about

invasive introduced trees from the 1950s and after.

The rise and decline of Clementsian paradigms

of invasion

The recognition that self-propagating introduced tree

populations threatened indigenous plants and vegeta-

tion types was delayed until the mid twentieth century

as a result of the arrival of Clementsian ecology into

South Africa during the 1910s–1920s (Pooley 2010:

602–6). Clementsian ecological theory encouraged

ecologists to downplay the late-Victorian ‘‘survival-

of-the-fittest’’ perspective that colonial foresters used

to explain the dynamics of introduced tree invasions.

A more benign view on invasion emerged in the 1910s

that lasted until the late 1930s and early 1940s.

The first generation of trained ecologists who began

working in South Africa during the 1910s and 1920s

were profoundly shaped by the American ecologist

Frederic Clements. Clements argued that ‘‘climax

communities’’ of vegetation, which were the culmi-

nation of progressive evolutionary stages, would

remain in equilibrium unless disturbed by an outside

Insights from South African history 503

123

force, such as deforestation, land clearing, or fire

(Worster 1994: 205–220). Clementsian advocates in

South Africa used this theory to argue that climax

communities would naturally resist introduced plant

invasions because foreign species could not outcom-

pete indigenous species that were better adapted to

local edaphic and ecological conditions.

Ecologists in South Africa recorded and analyzed

tree invasions in the Cape and Natal during the 1910s

and 1920s. These studies argued that, without distur-

bance, introduced tree populations would not invade

or radically modify South Africa’s indigenous vege-

tative communities. That is because ecologists

believed that the reproductive powers of introduced

plants were alone insufficient to extinguish indigenous

plants or change vegetation types. For instance, the

professor of botany at the University of Cape Town,

Robert S. Adamson, believed that (supposedly)

anthropogenic-induced fire caused the spread of

invasive Hakea and Acacia in the southwestern Cape

(Pooley 2010: 611). Studies from ecologists in Knysna

and Natal came to similar conclusions. In Natal, John

Bews observed that Acacia mearnsii invasions had led

to the local suppression of indigenous plants. But he

concluded that Natal’s vegetative communities were

‘‘resistant to invaders’’ on the whole (Bews 1916: 157

from Pooley 2010). John Phillips agreed. He witnessed

the invasive tendencies of Acacia melanoxylon along

the edges, rivers, and cuttings near the Knysna forest.

Yet Phillips concluded that wattle invasions were

unlikely to spread beyond a few clearings and along

some rivers because ‘‘native floras are not seriously

influenced by introduced species unless agents of

disturbance—principally the activities of man—assist

the advances of the latter’’ (Phillips 1928: 42).

Orthodox Clementsian views, such as those

expressed by Phillips above, began to soften in the

southwestern Cape during the late 1930s and early

1940s. Botanists, foresters, and ecologists there began

to observe rapid plant invasions and fear that intro-

duced trees could destroy the habitat of rare flowers,

beliefs that were ‘‘dissonant’’ with Cape ecologists and

botanists’ dominant Clementsian paradigm (Pooley

2010: 617). Adamson noted in his 1938 survey of

South African flora that, ‘‘The planting of these exotics

[trees] often has a very great effect on the native

vegetation, in extreme cases even leading to its

extinction’’ (Adamson 1938: 228). Though he most

likely referred to trees planted by humans (as opposed

to self-propagating trees), this marked one of the

earliest instances when trees were implicated with the

extinction of indigenous plants.

In 1945 a panel of esteemed scientists expressed

concerted alarm for the first time about the impact of

invasive vegetation in disturbed and undisturbed sites

in the southwestern Cape. The publication of the

landmark Report of the Committee on the Preservation

of the Vegetation of the South Western Cape cautioned

that ‘‘exotic and undesirable species’’ were spreading

at a disquieting rate. Chaired by Christiaan L. Wicht, a

forester and director of the Jonkershoek Forest

Research Station, the report alerted: ‘‘One of the

greatest, if not the greatest, threats to which the Cape

vegetation is exposed, is suppression through the

spread of vigorous exotic plant species. These exotics

are extremely difficult to control and possibly are

already out of hand’’ (Wicht 1945: 34).

By the 1950s, few botanists, ecologists, or

foresters who had worked in the southwestern Cape

still maintained the Clementsian theory that intro-

duced plants could not invade in undisturbed indig-

enous vegetation types. Ironically, the forester

Richard J. Poynton’s statement in 1957 that, ‘‘[P.

pinaster] shows very marked aggressive tendencies

and forms natural woods on [winter rainfall] sites

previously occupied by undisturbed natural vegeta-

tion,’’ merely confirmed what Hutchins had observed

in 1902 before the rise of Clementsian ecological

perspectives (Poynton 1957: 83).

Forestry researchers in the Cape began to recognize

that self-propagating introduced trees could under-

mine attempts to preserve indigenous vegetation and

to conserve water in the arid Cape. By the mid 1950s

foresters working for the Department of Forestry in the

Cape Province started to describe some invasive

introduced trees as ‘‘weeds’’ (Pooley 2012: 72).

Around the same time, researchers from the forest

hydrology research station at Jonkershoek demon-

strated that exotic trees transpired more water than

indigenous fynbos, lowering streamflow (Showers

2010: 311). In spite of research that showed that

introduced trees could have negative ecological and

hydrological impacts, the Department of Forestry

continued to afforest the Cape with introduced pines in

the 1960s and 1970s. This created ideal conditions to

promote tree invasions at the same time that it inspired

researchers and the public to become increasingly

concerned about these invasions.

504 B. M. Bennett

123

Becoming anti-exotic

Starting in the 1950s, a growing number of white

residents in the southwestern Cape began expressing

strong concerns that invasive introduced trees were

negatively impacting the Cape’s indigenous plants.

Whereas scientists pointed this out in the 1930s and

1940s, these concerns did not initially cause wide-

spread public anxiety. But by the 1950s professional

scientific observations became instilled in the minds of

white middle class residents in the Cape as a result of

highly coordinated educational effort between public

institutions, government departments and professional

and amateur scientists and conservationists. Indige-

nous floral advocates working at a variety of key

institutions—Kirstenbosch, the Department of Nature

and Environmental Conservation of the Cape Prov-

ince, University of Cape Town, Stellenbosch Univer-

sity, and the Jonkershoek Forestry Research Station—

worked together to inculcate a sense of reverence of

fynbos, at the same time that they warned against its

destruction. The legacy of these coordinated efforts to

educate white Cape residents about fynbos shaped the

study of invasive introduced trees throughout South

Africa from the 1980s onward.

Kirstenbosch Botanic Gardens, established in 1913

on the southern slopes of Table Mountain, played a

significant role in generating awareness about the

threats invasive introduced trees posed to the Cape’s

indigenous flora. The establishment of the University

of Cape Town in the neighbouring suburb of Ron-

debosch in 1918 created a powerful corridor linking

scientific researchers, botany students at the Univer-

sity of Cape Town, amateur botanists, and wealthy

white patrons who lived in the southern suburbs.

Kirstenbosch maintained an active research program,

undertook breeding efforts (to promote indigenous

gardening), and ran a popular educational program for

white students who lived near or around Cape Town

(Van Sittert 2003: 123). Students took school fieldtrips

to Kirstenbosch where they were shown beautiful

plants, told that the Cape was a ‘‘flower paradise’’

(Rycroft 1963), and informed by staff about ‘‘green

cancers’’ of invasive species (Hey 1995: 185).

The participation of engaged activists expanded

awareness of the problem through media and amateur

groups. Key individuals distributed professional scien-

tific research to the public. These included the popular-

iser D.H. Wood, who ‘‘tirelessly’’ penned articles for

Cape Town newspapers and Cape-based magazines

about the threat of invasive plants (Stirton 1978: 149);

Conrad Lighton, author of the popular Cape Floral

Kingdom (Lighton 1960); and female botanists, such as

Levyns, who served as liaisons between professional

botanists and ecologists and nature conservation groups.

Cape Province officials diffused and popularized

scientific knowledge about the threat of invasive

introduced trees. The Department of Nature and

Environmental Conservation of the Cape Province

played an important role in promoting the interests of

professional and amateur floral enthusiasts. Founded

in 1952, the Department of Nature and Environmental

Conservation advised on legislation, ran research

stations, and undertook educational activities, such

as publishing and distributing books on wildflower

protection and dangerous weeds written by university

and state botanists, ecologists, and agriculturists.

These ‘‘attractive publications’’ were designed pur-

posefully to build ‘‘awareness of the beauty and

value’’ of fynbos because officials sought to cultivate a

sense of reverence for indigenous flora in order to

inspire fear of invasion: ‘‘public awareness both of the

invaders, and what they threaten—is an integral part of

the control effort’’ (Stirton 1978: 150). Department

publications such as A Nature Conservation Hand-

book (Hey 1957), Nature Conservation in the Prov-

ince of the Cape of Good Hope (Dept. of Nature

Conservation of the Cape Provincial Administration

1960), and Plant Invaders: Beautiful but Dangerous

(Stirton 1978) informed the public about the Cape’s

invasive plant problem.

Cape residents founded what was probably South

Africa’s first introduced tree eradication movement.

Scientists and concerned citizens formed the Control

of Alien Vegetation Committee in 1958 as a section of

the Wild Flower Protection Society Committee

(Botanical Society of South Africa 1960). The com-

mittee commissioned and published, Green Cancers

in South Africa: The Menace of Alien Vegetation

(Control of Alien Vegetation Committee 1959), to

warn the public about the negative impacts of invasive

introduced plants, especially trees. The misleadingly

titled book actually only focused on invasive intro-

duced trees in the Cape, not throughout all of South

Africa (not unlike the Botanical Society of South

Africa focused more on the Cape than elsewhere). The

Committee, along with members of other Cape

volunteer societies, formed the first ‘‘hack parties’’

Insights from South African history 505

123

that trekked across the Cape destroying introduced

trees on mountains.

The combination of an active citizenry, concerned

scientists, and government support entrenched the

view that invasive introduced trees threatened the

existence and diversity of fynbos. After being estab-

lished in the 1950s, this view continued to direct

scientific research and educational programs in the

Cape for the rest of the century. Yet only in the Cape

did this view take hold so quickly and firmly. In other

regions of South Africa the belief that introduced trees

threatened indigenous vegetation developed decades

later.

Cape regionalism or South African nationalism?

There is little evidence to suggest the Cape’s high

level of public and scientific concern about the

ecological impact of invasive introduced trees was

found elsewhere in South Africa prior to the 1980s.

From 1950 to 1980 there was little sustained attention

given to the perceived negative impacts of invasive

introduced trees outside of a Cape, and more specif-

ically, fynbos context. There was indeed awareness of

invasive plants (e.g. herbaceous, shrubby, aquatic, or

creeping invasive introduced plants or weeds) in South

Africa, but on the whole these observations and

interests were not linked with introduced trees or fears

about the extinction of indigenous flora. There is, for

instance, scant evidence to suggest that Cape-oriented

publications such as Green Menace (1959) and Plant

Invaders: Beautiful but Dangerous (Stirton 1978)

‘‘gained momentum in the late 1950s and early 1960s’’

outside of the Cape (Carruthers et al. 2011: 813).

This statement is demonstrated by the paucity of

published and unpublished scientific literature focused

on trees as invaders and weeds outside of the Cape

prior to the 1980s. There was not, for instance, a single

study referenced focusing on tree invasions in the

Transvaal or Natal in a comprehensive bibliography of

ecological research ongoing in 1979 (Committee for

Terrestrial Ecosystems 1981); and only a handful of

scattered studies that focused on these regions before

1980 were listed in Moran and Moran’s bibliography

of invasive plants since 1830 (1982). Scientists noted

that there was no sustained attempt to study the

extensiveness and impact of invasive introduced trees

in the Transvaal before 1979 and in Natal before 1980

(Farrar and Kruger 1983: 12).

Conservation scientists working in other regions

recognized from the 1950s and on that introduced trees

were highly invasive in fynbos, but expressed little

concern about introduced tree invasions in other

biomes. For instance, in 1958 T.J. Steyn, the Director

of Transvaal government’s Nature Conservation Divi-

sion, declared in the department’s official publication

Fauna and Flora: ‘‘The threat to indigenous flora [by

invasive plants in the Transvaal] thus far experienced

in the Transvaal is negligible in comparison with the

position in the Western Province, for example’’ (Steyn

1958: 21). In the same article, Steyn listed the

Transvaal’s worst weeds—not a single introduced

tree was mentioned. Expansion of native woody

vegetation—bush encroachment—was a more signif-

icant problem because South Africa’s cattle industry

and its large game reserves (e.g. Kruger National Park)

were located predominately in the savanna biome in

the northern and eastern Transvaal (Feinstein 2005:

267). Unlike introduced tree invasions, which since

the 1940s had been recognized to occur in undisturbed

fynbos, the expansion of encroaching native trees in

savanna was explained more simply as a consequence

of improper land management, especially overgrazing

(see Walter 1971).

There was a lag in the appreciation of the biological

uniqueness and diversity of South Africa’s extensive

grasslands and coastal forests, a factor that may have

delayed appreciation of the extent and impact of

invasive trees. Compared with fynbos or savanna,

there was less of an appreciation for the aesthetics and

biodiversity of grasses (Bond and Parr 2010) and some

indigenous coastal forest types in Natal (Sundnes

2013) prior to the 1980s. Johannesburg, Bloemfontein,

and Pretoria are located in grassland, one of the least

protected and most threatened biomes in South Africa.

Durban is located in Coastal Thicket, a highly

fragmented and degraded biome. Farming and urban

expansion, particularly around Johannesburg and

Durban (Ellis 2002), caused the widespread destruc-

tion of indigenous flora.

The relative economic importance and ownership

structure of timber plantations also distinguished the

southwestern Cape from other parts of the country.

After Union in 1910 the Forestry Department shifted

its focus away from the Cape and towards higher

rainfall areas in the east and north (Bennett 2011:

277–8). The majority of South Africa’s new plantation

expansion occurred in Natal, Zululand, and the

506 B. M. Bennett

123

Transvaal. Private plantations accounted for over

70 % of the plantation estate during the second half

of the century (Bennett 2010: 36). Private sector

linkages changed the dynamic of forest-based research

outside of the southwestern Cape. Forest researchers at

the Wattle Research Institute, established in 1947 at

Natal University in Pietermaritzburg, were mandated

to work closely with private wattle plantation owners.

In one instance, attempts by WRI officials to negotiate

with private owners to pursue biological control for

Acacia in the 1970s failed because owners felt it would

limit profits (Impson et al. 2009: 43). There were fewer

privately owned timber plantations in the southwest-

ern Cape because the region’s aridity was less

conducive to fast-growing tree species. Most timber

plantations (mainly Pinus radiata) were government

owned. This fact explains why government foresters

could take the lead in studying and managing invasive

trees on government land in the southwestern Cape.

Invasive introduced trees go national

A groundswell of interest in biological invasions

blossomed in South Africa during in the late 1970s and

early 1980s as a result of the intersection of key

scientific, environmental, and cultural trends. There

was a greater nation-wide awareness that the problem

of invasive and weedy plants (native and introduced

species) seemed to be getting out of hand. For the first

time, the negative ecological impacts caused by

invasive introduced trees were seen as a national

problem rather than something that was isolated to the

Cape. Scientists met at interdisciplinary conferences

and national and international research conferences to

discuss regional problems and to theorise the ecolog-

ical and biological dynamics of invasion. These

concerns reflected not only the fact that South Africa’s

environment had been reshaped by self-propogating

populations of introduced species, but also indicated a

rising tide of environmentalism and ecological con-

sciousness that sought to stop pollution and maintain

South Africa’s biomes in pristine and wild forms.

South Africans in the 1970s and 1980s expressed

unique local variants of broader global environmental

anxieties over pollution, the destruction of rare and

fragile ecosystems, and extinction. The South African

botanists A.V. Hall and C.H. Boucher drew parallels

in 1977 between ‘‘industrial air pollution’’ and inva-

sive Australian wattles which ‘‘polluted our vegetation

and our landscapes’’ (Low 2001: 165) Concerns about

pollution led many to seek to preserve South Africa’s

environment in pristine forms. The concept of ‘‘wil-

derness’’ permeated South African discussions of

conservation management after the First World Wil-

derness Conference was held in Johannesburg in 1977

(Player 1977; Hey 1995: 242–3). Conservation groups

in KwaZulu-Natal began to focus on preserving

indigenous ecosystems in their ‘‘pristine’’ indigenous

form during the early 1980s (Sundnes 2013).

A more coherent understanding of the scale of

South Africa’s invasive plant problem emerged as a

result of meetings between agricultural, forestry,

ecological, and botanical researchers at a series of

national weeds conferences held in Pretoria in 1974,

Stellenbosch in 1977, and Pretoria in 1979 and 1981.

These meetings encouraged weed researchers, who

often focused on agricultural pests and biological

control, to collaborate with researchers concerned

about invasive species in state forests, parks, and

reserves. The WEEDS conferences preceded and

informed the drafting South Africa’s Conservation of

Agricultural Resources Act, 1983 (Act No. 43). The

Act listed numerous species of Australian Acacia,

Hakea and Pinus into two categories, ‘‘declared

weeds’’ or ‘‘invader plants,’’ depending on their

impact. This was the first time many introduced tree

genera and species gained standing as national weeds.

Ecological researchers working with the Council for

Scientific and Industrial Research (CSIR) reinforced

the growing interest in South Africa’s ‘‘pristine’’

ecosystems by embarking on a major national project

to detail the essential ecological processes and struc-

tures of South Africa’s distinct vegetative biomes.

CSIR instigated the first biome-specific research

project during the 1970s in response to the IUCN’s

International Biological Program. The first multidis-

ciplinary project, led by Brian Huntley, focused on

savanna. As a result of the success of this project, CSIR

started a fynbos project in 1977 and other projects on

grasslands (1982), forests (1985) and Karoo (1986).

From the outset, the Fynbos Biome Project paid

significant attention to how invasive plants, especially

trees, negatively impacted fynbos’ ecological func-

tioning. The initial abstract for the Fynbos Biome

Project stated: ‘‘Particular emphasis is being devoted to

major environmental problems such as invasive plants

and the ecological effects of fire’’ (Kruger 1978: iv).

The Fynbos Biome Project sustained research on fire

Insights from South African history 507

123

and invasive introduced trees in fynbos that Frederick J

Kruger had initiated at the Jonkershoek Forest

Research Station in the late 1960s (Pooley 2012:

66–8). Researchers working at the South African

Forestry Research Institute, influenced for much of the

decade by its Deputy-Director for Conservation For-

estry and then Director (1984–1990) Kruger, played a

particular important role in researching invasive spe-

cies. Leading scholars of fynbos and invasion—

including William Bond, David Le Maitre, Jeremy

Midgley, Dave Richardson, and Brian van Wilgen—all

worked with SAFRI during the life of the Fynbos

Biome Project.

The Fynbos Biome Project ran parallel with a series

of Mediterranean-climate ecosystem conferences

(MEDECOS) founded by the eminent Stanford ecol-

ogist Hal Mooney in 1971. These meetings and the

comparative framework that arose from them

prompted researchers to become more concerned that

invasive species were becoming a major global

environmental problem in Mediterranean-climate

ecosystems. Interactions between Mooney and Kru-

ger, who attended the second 1977 (Stanford) and third

1980 (Stellenbosch) meetings, helped lead to the

creation of a coherent international research program

on invasion biology. Researchers at the meeting were

struck by the density and extensiveness of pine

invasions in fynbos. As a result, Mooney and Kruger

decided to call for a ‘‘post-Elton global assessment of

the status of invasive species’’ in Mediterranean-

climate ecosystems at the upcoming 1982 Ottawa

meeting of the Scientific Committee on Problems of

the Environment (SCOPE) (Richardson 2011: xi;

Simberloff 2010: 16). At the Ottawa meeting their

proposal was ‘‘upgraded’’ to a full global investiga-

tion. This proposal was approved, and SCOPE’s

project began internationally and in South Africa in

1983. South African researchers produced a detailed

regional survey of invasion (Macdonald et al. 1986)

and contributed to the 1989 global synthesis on

invasion biology (Drake et al. 1989).

The SCOPE agenda provided a broader national

umbrella that linked together disparate provincial

research projects on weeds and invasive species,

especially trees, that started during the 1970s and early

1980s. Prior to the instigation of the SCOPE project,

researchers in Natal and the Transvaal began to survey

and map tree invasions to understand the extensive-

ness and impact of these invasions. In 1980, the Parks

Board of Natal instigated a survey to find out the extent

to which woody vegetation had invaded Natal’s

reserves (Farrar and Kruger 1983: 12). A year earlier

researchers in the Botanical Research Institute (BRI)

began to survey invasive introduced trees in the

Transvaal. When they announced the results of their

first findings at the Third Annual Weeds Conference in

1980 they commended Cape researchers for ‘‘rightly’’

studying tree invasions in fynbos. They then noted

that, ‘‘relatively little notice has been taken of

introduced, woody invaders in other ecosystems

[outside of the Cape] in South Africa e.g. the bushveld

and grassland ecosystems of the Transvaal’’ (Wells

et al. 1979: 11).

Botanical Research Institute researchers led by

Henderson implemented the first Transvaal-wide and

nation-wide investigation into invasive plants. This

investigation was by its very design skewed towards

identifying invasive introduced trees because trees

could be more easily identified from the road than

other plant types. The BRI team completed their

survey of the Transvaal in 1982–1983. They then

surveyed Natal (Henderson 1989), the Orange Free

State (Henderson 1991a), and then the northern Cape

(Henderson 1991b), eastern Cape (Henderson 1992)

and the south and southwestern Cape (Henderson

1998) on an on-going project from 1986 to the mid

1990s. This roadside mapping eventually formed the

empirical basis for the African Plant Invaders Atlas,

created by Henderson and inaugurated in 1994 (Hen-

derson 1995). The results of these surveys found that

fynbos was the most densely invaded biome in South

Africa, but that the savanna biome had the most

number of invasive species (in total) and grasslands

were also heavily invaded (Henderson 2007: 220).

The results of the Transvaal roadside surveys were

publicised by the government to warn Transvaal

residents about the growing threat of invasive intro-

duced trees. In 1987, the Department of Agriculture

and Water published the public pamphlet Plant

Invaders of the Transvaal. This book was similar in

tone and content to Green Cancers (Control of Alien

Vegetation Committee 1959) and Plant Invaders:

Beautiful But Dangerous (Stirton 1978). It cautioned:

‘‘in all parts of South Africa, alien plants are gaining a

foothold of varying degrees’’ (Henderson and Musil

1987: 1) This included not only the more visible Cape

invasions, but also tree invasions in the Transvaal:

‘‘Woody alien invaders in the Transvaal, were recently

508 B. M. Bennett

123

the subject of a research study which indicated that

some of the indigenous plant communities in the

northeast part of the country face invader threats

comparable to those of the more widely publicized

Cape fynbos’’ (Henderson and Musil 1987: 1–2).

Ironically, at the same time when researchers across

South Africa became aware that invasive species were

a serious national environmental problem, the national

government devolved the management of invasive

plants in catchments, South Africa’s most significantly

invaded ecosystems. Since the late 1970s foresters in

the fynbos-dominated southern and western Cape

regions had used fire to control invasive species in

catchment areas (Pooley 2012: 72). This was part of a

larger integrated catchment management strategy to

increase stream flow and conserve fynbos diversity.

As a result of budget cuts, the President’s Minute 1109

in November 1986 devolved the management of

mountain catchments away from the national to

provincial governments on 1 April 1987 (Pooley

2012: 74). Provincial governments lacked the financial

or scientific capabilities to maintain the program. They

proved unable to continue fire-management policies in

catchments. South Africa lacked a management pro-

gram for controlling invasive species in catchments

until after the end of apartheid.

The establishment of Working for Water in 1995

ushered in a new era that linked introduced invasive

plant eradication programs with South African nation-

alism. The idea for WFW—that introduced trees use

more water than indigenous vegetation—came largely

from the findings at Jonkershoek Forest Research

Station. When the government established WFW in

1995, it also abolished continuous funding for the

Jonkershoek Research Station after its last government

contracts ran out when SAFRI became part of CSIR

and was renamed Forestek (Pooley 2012: 74).

Whereas Jonkershoek was created in 1935 to apolit-

ically solve a major scientific and public conflict,

WFW applied knowledge gained from Jonkershoek’s

research program to pursue an explicitly political

project that linked invasive plant control with eco-

nomic growth, poverty relief, and national identity.

Rather than funding invasive species control efforts

through traditional departments (e.g. forestry), WFW

was created as a poverty-relief program that focused

on eradicating invasive plants that transpire limited

water supplies in catchment areas. One of the key

aspects of WFW is that it has sought to create a form of

post-apartheid South African nationalism spanning the

entire country. The program was created to bring:

community development and scientists together,

involving them jointly in invasive species con-

trol and encouraging a form of nationalism that

resonates with conserving an indigenous biodi-

versity and promoting sustainable development

and resilient ecosystems….an attitude that

Pauly…refers to as national ‘ecological inde-

pendence’ (Carruthers et al. 2011: 815).

Working for Water has indeed sought to naturalise the

nation-state, as the Comaroffs suggested, by arguing

that ‘‘alien’’ plants negatively affect South Africa’s

economy, biodiversity, and water supply while

‘‘natives’’ promote sustainable economic growth and

create positive ecological services (Comaroff and

Comaroff 2001). In a sense, the Comaroffs are correct:

a new ecological nationalism has arisen after the end

of apartheid. Though this type of nationalism devel-

oped after apartheid, it draws heavily on older popular

concerns and Cape-based scientific research.

Though there has a been a growth in scientific and

public awareness of invasive introduced trees outside

of the Western Cape Province, Cape-based institutions

and researchers still predominately shape research on

invasive species policies and research directions in

South Africa. A survey published in 2007 showed that

55 % (89 people in total) of all experts on invasive

species who lived in South Africa worked in the

Western Cape, and 84 % of them (75 people) were

located in the greater Cape Town metropole (Musil

and Macdonald 2007: 4). The second greatest con-

centration of expertise was located in Gauteng, where

32 experts resided (20 % of South African experts)

with 21 experts living in Pretoria and 11 living in

Johannesburg, South Africa’s largest urban popula-

tion. This geographic imbalance is indicative of the

distinct yet interconnected histories of regions

described in the paper.

Conclusions

The history of how perceptions of invasive introduced

trees first arose in the southwestern Cape and spread

throughout South Africa offers fundamental insights

into how scientists and the public became concerned

about the impact of invasive introduced trees. The

Insights from South African history 509

123

rapid growth of public concerns about invasive trees

around Cape Town beginning in the 1950s was built

on pre-existing scientific concerns that were sustained

by educational efforts directed towards the construc-

tion of emotional and cultural attachments with the

surrounding flora and landscapes. Anxieties about tree

invasions in fynbos later encouraged researchers in

other parts of the country to begin investigating the

ecological impact of invasive trees in the 1970s and

1980s.

With this history in mind, it may be sensible for the

South African government to spend more money on

education and biological control and less on menial

labour meant to control invasives. Currently, 92 %

cent of WFW’s budget goes to manual labour for

clearing plants with only 3 % each going to more cost-

efficient biological control methods (van Wilgen et al.

2012: 35) and education programs for school children,

landowners, and the public (Staff Induction Manual

2008: 17). Awareness about the problem of invasive

species should also coincide with the cultivation of

knowledge about the uniqueness of indigenous flora

and fauna. A focus on regional natures, rather than

national ones, may alleviate some of the problems—

e.g. nationalism and xenophobia—associated with

imagined national natures. Such a region-based pro-

gram would fit, rather than fight, the distinct regional

cultures and ecologies that have historically consti-

tuted the nation of South Africa.

The history of invasive introduced trees in South

Africa has wider relevance for international scholars

researching the history and science of invasive

species. This article suggests that certain model

invasions (in this case, invasive trees in the south-

western Cape) disproportionately influenced scientific

researchers around the world to become concerned

about invasion more generally. Further historical

research is required to understand what other model

invasions and places contributed to the global prolif-

eration of interest in invasive species during the 1980s

and 1990s, the founding decades for the discipline of

invasion biology. Yet from this example it is clear that

the discipline and theoretical foundations of invasion

biology developed from particular examples of inva-

sion that arose within ecologically, geographically and

culturally unique regions. The southwestern region of

South Africa was one of the most globally significant

localities that shaped the origin of the field of invasion

biology and led to the development of modern

scientific and public concerns about introduced inva-

sive species.

Acknowledgments BMB was supported financially by the

School of Humanities and Communication Arts at the

University of Western Sydney. This paper was greatly

improved by valuable criticism from Dave Richardson and

two anonymous reviewers; any mistakes or changes are entirely

my own. I benefited from discussions with participants during

the Tree Invasions Workshop held in Bariloche, Argentina,

September 3–5, 2012. I thank Brian van Wilgen, Marcel

Rejmanek, and Frederick J. Kruger for their comments on the

manuscript. Lance Van Sittert offered valuable insights on a

visit to Cape Town in March 2013.

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