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20 Conservation of Wild Plants - DAVID R. GIVEN AND NIGEL MAXTED

20 Conservation of Wild Plants - DAVID R. GIVEN AND NIGEL MAXTED

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388 • The Cultural History of Plants



TABLE 20.1 Regional Distribution of Higher Plants (World Conservation Monitoring Centre 1992)

Number of Species

Region



Sub-region



Sub-region



Europe

Americas



Continent

12,500

133–138,000



North America

Middle America

South America

Caribbean Islands



%



3500



28



40–45,000



4198

14–19,000

55,000

6,555

35,000



21

46–54

78.5

50

77–87.5



23,000



7,100



31



17,500

25,000



2,500

12,000



14

48



42–50,000



29–40,000



70–80



17,580



18,650

16,202



41.5

90



11–12,000

380–399,000



7,000

216–234,000



58–63



20,000

30–35,000

70,000

13,000



Africa

North Africa

Tropical Africa

Southern Africa



Endemics

Number



10,000

21,000

21,000



Asia



Australasia

Oceania

Totals



Southwest Asia &

Middle East

Central & North

Indian

Subcontinent

Southeast Asia

(Malesia)

China & East Asia

Australia &

New Zealand

Pacific islands



45,000



in its infancy, and early indications are that although some areas of species richness also have

matching genetic diversity, some unexpected patterns are emerging. The issue is partly clouded by

the impact of centuries of migrating human groups taking favored plants with them when colonizing distant lands.

See: Conservation of Crop Genetic Resources, pp. 413–429

The Reality of Extinction

A recent declaration by leading botanical scientists drawing attention to the need for concerted global effort to conserve plants considers that “as many as two-thirds of the world’s plant species are in

danger of extinction in nature during the course of the 21st century, threatened by population

growth, deforestation, habitat loss, destructive development, over-consumption of resources, the

spread of alien invasive species and agricultural expansion” (BGCI 2000).

Extinction is not just a future phenomenon and not just the highly visible loss of larger animals:

plant extinctions are being recorded at the present time. Thomas Givnish noted the demise of a species of Cyanea (Lobelioideae family) on the Hawaiian Islands, and Arnoldo Santos-Guerra documented the extinction through animal grazing of the last wild population of a plant species on La

Palma in the Canary Islands. Fortunately, Santos-Guerra was able to salvage ripe seeds and introduce

the species into a botanic garden (Josephson 2000). However, while salvaging a few viable seeds may

literally save a species from extinction at the eleventh hour, there remains the problem of how often it

is feasible to restore viable wild species back from such a bottleneck without enormous expenditure.

We need to prevent human-induced extinction factors from operating in the first place.



California Floristic

Province

Philippines



Caucasus

Wallacea (Indonesia)



South Central China

Madagascar and

Islands



Mesoamerica



Atlantic forest region



Guinean forest

Tropical Andes



Sundaland (Indonesia)



Brazilian Cerrado



Mediterranean Basin

Indo-Burma



Hot Spots



324,000

300,780



Tropical rain forest



500,000

346,782



800,000

594,221



1,154,912



1,227,600



1,265,000

1,258,000



0.20



0.21



0.34

0.23



0.53

0.40



0.77



0.82



0.85

0.84



1.08



1.20



1,783,169



1,600,000



1.59

1.40



2,362,000

2,060,000



24,062



80,000



50,000

52,017



64,000

59,038



230,982



91,930



126,500

314,500



125,000



356,634



110,000

100,000



(km2)



8.0



24.7



10.0

15.0



8.0

9.9



20.0



7.5



10.0

25.0



7.8



20.0



4.7

4.9



(%)



Remaining Intact



(km2)

(%)



Original Extent



Mediterranean type

Tropical rain forest/Tropical

dry forest

Tropical dry forest

Woodland savannah

Open savannah

Tropical rain forest

Tropical dry forest

Tropical rain forest

Tropical rain forest

Tropical dry forest

High-altitude grass

Tropical rain forest

Sub-tropical rain forest

Tropical rain forest

Tropical dry forest

Temperate forest Grassland

Tropical rain forest

Tropical dry forest

Xerophytic vegetation

Temperate forest Grassland

Tropical rain forest

Tropical dry forest

Xerophytic vegetation

Mediterranean type



Biome(s)



Geographic Area



3910



31,443



14,050

20,415



16,562

11,546



138,437



33,084



20,224

79,686



90,000



22,000



42,123

160,000



(km2)



1.3



9.7



2.8

5.9



2.1

1.9



12.0



2.7



1.6

6.3



5.6



1.2



1.8

7.8



(%)



Area Protected



TABLE 20.2 The Twenty-five Hot-spots, Their Characteristics, and Biodiversity (after Mittermeier, Myers, and Mittermeier, 1999)



7620



4426



6300

10,000



12,000

12,000



24,000



20,000



9000

45,000



25,000



10,000



25,000

13,500



Diversity



(Continued)



5,832



2,125



1,600

1,500



3,500

9,704



5,000



6,000



2,250

20,000



15,000



4,400



13,000

7,000



Endemism



Vascular Plants



Indicative Biodiversity



Conservation of Wild Plants • 389



Galapagos

Juan Fernandez Island

Totals

Total Endemics

% Global Diversity



Eastern Arc Mountains

New Caledonia



Choco-Darien/

Western Ecuador

Western Ghats and

Sri Lanka

Succulent Karoo

(Africa)

Cape Floristic Province

Polynesia/Micronesia

74,000

46,012



Mediterranean type

Tropical rain forest

Tropical dry forest

Tropical rain forest

Tropical rain forest

Tropical dry forest

Maquis shrubland

Xerophytic shrubland

Temperate forest

7882

100

17,452,038



30,000

18,567



112,000



Xerophytic vegetation



Geographic Area









2,142,839



11.76



1.44



62.6



4931



6.7

28.0



24.3

21.8



27.0



6.8



24.2



11.3



30.0

22.0



(%)







2000

5200



18,000

10,024



30,000



12,445



63,000



29,840



90,000

59,400



(km )



2



Remaining Intact



0.005



0.02

0.01



0.05

0.03



0.08



0.12



182,500



0.17



0.17



263,535



0.20

0.18



(%)



260,595



Caribbean



300,000

270,534



(km )



2



Original Extent



Tropical rain forest

Tropical dry forest

Xerophytic vegetation

Tropical rain forest

Tropical dry forest

Tropical rain forest



Mediterranean type

Temperate forest Grassland



Biome(s)



Central Chile

New Zealand



Hot Spots



TABLE 20.2 (Continued)



7278

91

888,789



5083

527



14,060

4913



2352



18,962



16,471



41,000



9167

52,068



(km )



2



92.3

91.0

0.60



16.9

2.8



19.0

10.7



2.1



10.4



6.3



15.6



3.1

19.2



(%)



Area Protected



541

209



4000

3332



8200

6557



4849



4780



9000



12,000



3429

2300



Diversity



131,399

43.8



224

126



1,400

2,551



5,682

3,334



1,940



2,180



2,250



7,000



1,605

1,865



Endemism



Vascular Plants



Indicative Biodiversity



390 • The Cultural History of Plants



Conservation of Wild Plants • 391



Despite our considerable knowledge of plant distribution and abundance, it can be extremely

difficult to assess global extinction rates, especially when they are projected into the future. A critical review of the extinction problem using three contrasting analyses concluded that impending

extinction rates are at least four orders-of-magnitude faster than the background rates seen in the

fossil record (May et al. 1995, 1–24). This figure does not take into account the assertion that the

extinction of an obvious, large keystone organism (such as a forest tree) probably results in the loss

of up to ten or twenty other smaller organisms dependent on or confined to that single species.

Recent analyses of possible extinction rates by Stuart Pimm and Peter Raven paint a bleak scenario for the future of biodiversity unless markedly increased steps are taken to protect the remaining species-rich regions and habitats (Pimm and Raven 2000). This model suggests an accelerating

rate of extinction, peaking in the mid-21st century at nearly 50,000 per million species (of both

plants and animals), then decreasing into the 22nd century.

As expected, the most critical parts of the world are the biological hot-spots that are rich in species found nowhere else. A disturbing feature of this analysis is that in the seventeen tropical regions

designated as biodiversity hot-spots, only 12 percent of the original primary vegetation remains.

Applying the Pimm and Raven model, one arrives at the prediction that even if the entire remaining

habitat in these seventeen areas were protected immediately, there would still be an 18 percent loss

of their species, and if habitat depletion continued at the present rate for a further decade, the species loss would rise to 40 percent.

Urban areas where the species are visible to a greater number of people can also be major extinction sites. An example is Thismia americana, only ever known from one locality in Cook County,

Chicago, where it was last seen in 1913. The site, originally described as being “the bottom prairie

swale on the east side of Calumet Lake, between Torrence Avenue and Nickel Plate Railroad,

between the Ford factory and the Solway Coke factory” is now under heavy industry. The species

has been searched for repeatedly in the original area and in similar sites, but without success. It is

not in cultivation and is now believed to be extinct (Lucas and Synge 1978).

Main Extinction Threats: Successes, Failures

What factors lead to extinction? It is important to appreciate that both species extinction and loss

of genetic diversity, or “genetic erosion”, can be natural events, just as some forms of evolution are.

Nature is, and it seems has always been, dynamic—there are natural background rates of extinction.

However, the contemporary situation concerning species’ extinction and genetic erosion is quite

different from that which existed in the past. Humankind now has the ability to alter drastically the

world environment in ways not previously possible. Therefore, loss of plant biodiversity is mostly

caused by humans, and these causes may be broadly grouped under the general headings of:

• Destruction, degradation, and fragmentation of natural habitats (e.g., by road and reservoir building)

• Overexploitation (e.g., by medicinal plant extraction from the wild, fuel wood gathering,

overgrazing)

• Introduction of exotic species which compete with, prey on, or hybridize with native species (e.g., human introduction of alien species for exploitation that subsequently escape

and become novel weeds or pests) (see Invasives)

• Human socio-economic changes and upheaval (e.g., extinction of tribal cultures, urban

sprawl, land clearances, food shortages)

• Changes in agricultural practices and land use (e.g., displacement of land races or traditional cultivars by modern varieties or shift to monoculture)

• Calamities, both natural and man-made (e.g., floods, landslides, or wars)



392 • The Cultural History of Plants



Threats to survival can be direct (as with harvesting) or indirect (as with habitat removal or

extirpation of an essential pollinator or seed disperser). Also, threats can be extrinsic—generated

outside the plant and its population—or intrinsic—a factor in the biology of the species that makes

it especially vulnerable to an environmental change. An example of the former is the destruction of

individuals or predation on fruits or flowers; an example of the latter is relying on fertilization by a

specific insect pollinator that can be readily eliminated from the ecosystem, leading indirectly to the

demise of the plant species.

At the ecosystem level, climatic modeling studies suggest that since the beginning of agriculture,

some 15 percent of forests had been converted to cultivation by 1970. A study by FAO and UNEP of

eighty-seven countries found that, between 1980 and 1990, about 169 million hectares (418 million

acres) of forest were lost, or about one percent per year. It is estimated that western Ecuador, one of

the areas of the world most rich in biodiversity, has lost 90 percent of its forest since 1950, and possibly up to half of its complement of indigenous plant species. Over 90 percent of natural wetlands

in New Zealand have been lost since European settlement in the 17th century (Given 1981). More

than 90 percent of other major ecosystems are either disappearing or being fragmented, and so losing their self-sustaining viability. Loss of mangrove forests along tropical coasts is rapid, with figures

of 40 to 80 percent in the last 20 years being quoted for countries such as Thailand, Philippines, and

Gambia. A UNEP study suggested that some 69.5 percent of the world's drylands have, to some

extent, been degraded as a result of adverse human impacts. It is more difficult to measure genetic

erosion, either within or between species, and also the extent of genetic pollution of wild species

through contact with cultivars and imported species, whether in the form of crops or amenity

plantings.

Species do not have to entirely disappear to become functionally extinct. An increasingly common phenomenon is what has been sometimes called the “living dead.” These are species that are

still present as adults, but whose reproduction has virtually ceased, and so are functionally “dead”.

New Zealand provides a good example. Shrubby pohuehue (Muehlenbeckia astonii, of the dry scrub

of the northeastern South Island of New Zealand) is a strange plant, shaped like a bouncy igloo of

interlacing branches. About 2000 plants are known, but these are all probably at least 100 years old,

and only a handful of seedlings and juveniles have been seen in recent years. Reproduction is virtually unknown, and few individuals of the species play an effective ecosystem role. Shrubby pohuehue is perhaps the most extreme example of functional extinction in this region, but close

examination of a number of its companion shrubs suggests that many are doing little better. The

intricate and fascinating mosaic of divaricating shrublands in this part of the world, unimaginatively called “grey scrub” in the textbooks, may join the dodo, the moa, and the passenger pigeon as

museum pieces (Given 2001). There are strong arguments for a prophylactic approach to conservation, rather than waiting for a crisis of extreme endangerment and expending limited conservation

funds on species that are close to extinction and may not be successfully saved for posterity.

Threatened Species and Priorities

Increasingly, data on plant species’ abundance, biology, and distribution is being used to determine

the conservation status, or degree-of-risk of extinction. There has been much debate about the categorization process and how to best list species. An important distinction is between categorizing species in terms of extinction risk (for example, the process of Red Listing—see later discussion) and

setting priorities for conservation action that involves other types of information, such as cultural

importance, significance for commercial use, and likely cost and success of a recovery program.

There is a general assumption that about 12.5 percent of the world’s flora is globally threatened.

This is probably an underestimate for two reasons. First, it can be difficult to prove that a species is

extinct, even when there have been repeated searches of likely sites. Second, although threat assessment



Conservation of Wild Plants • 393

Extinct in the Wild

Extinct



Critically Endangered

(Threatened)



Endangered

Vulnerable



(Adequate

data)



Conservation

Dependent

Lower Risk



Near Threatened



(Evaluated)

Least Concern



Data Deficient

Not Evaluated



Figure 20.1. Structure of the IUCN categories of threat (http://www.redlist.org/).

systems have been in use both at the country level and globally for a number of years, it is only

recently that an integrated and replicatable global system has been phased in to cope with large

numbers of species from very diverse taxonomic groups.

The International Union for Conservation of Nature and Natural Resources (IUCN) has developed

a global system of categories of conservation status, which ideally requires knowledge of distribution,

population size, and population dynamics of the species concerned, although approximations can be

made if precise data is not available (IUCN 2001). This is the IUCN Red Data System or Red List

(Fig. 20.1). Inventories in 1997 and 1998 suggest that approximately 34,000 plant species are threatened

to some degree worldwide, with some 6,500 in the Endangered category, meaning they are likely to

become extinct in the near future (Oldfield, Lusty, and MacKinven 1998, Walter and Gillett 1997). The

1997 study lists 751 described species from 192 families that are thought to be extinct in the wild. There

are numerous estimates of predicted extinction rates, but a widely held view is that 15 to 20 percent of

all plant species could become extinct in the next 20 years, even though at present many countries recognize only about 12 percent of their flora as being at risk.

An important rationale for identifying hot-spots of biodiversity is that priorities must be set for

use of the limited resources available for conservation. Norman Myers and others have warned that

conservationists may not be able to assist all species under threat, if only because of lack of funding.

Therefore, we must place a premium on setting priorities. This is part of the rationale of identifying

biodiversity hot-spots. A concerted effort to achieve substantial and immediate protection of these

twenty-five regions, which comprise only 1.4 percent of the Earth’s land surface, would protect

as many as 44 percent of all plant species. As noted in the chapter on conservation of crop genetic

resources, there are good arguments for giving priority to those species (and ecosystems and geographic regions) that have multiple gene pools within the “gene sea” of interrelated gene pools,

because they would better represent the breadth of the plant genetic diversity in the limited number

of populations or accessions likely to be actively conserved.

Another aspect of prioritization useful when detailed information is not available is to estimate

proneness to extinction, based on inherent biological characteristics of species (or genera).

Frequently little is known about species that may be at risk since often time and resources do not



394 • The Cultural History of Plants



allow in-depth study before decisions on priority have to be made. This has led to the development

of various methodologies for pre-assessing extinction risk (Fiedler and Ahouse 1992, Given 1994,

Mace et al. 2001).

Protected Areas and in situ Conservation

Conserving plants in their natural habitat is often regarded as the mainstay of plant species conservation, but this involves more than the simple expedient of putting a fence around a few individuals.

Most species, except those that are recent immigrants, have evolved in concert with other species and

environmental factors such as climate, soils, and moisture. Even the simplest of ecosystems are rarely

random selections of animals and plants thrown together, but rather complex networks of mutual

interactions and interdependencies. Thus, conservation of individual species needs to take into

account the communities within which species occur, its genetic makeup, the particular role they play

in maintaining other parts of the system, and the species on which they themselves depend.

Communities include many feedback loops with a constant interplay of animals, plants, and

physical factors, which in various ways reinforce processes that change through time. This raises

important questions for management of communities and ecosystems: What happens when communities are stressed in various ways? What species losses can be expected on the basis of community structure? Are some kinds of communities more susceptible to catastrophes and species

invasions than others? What kinds of species invade and what is their effect? Will the loss of one

species cause other losses to cascade through the community, and if so, how far? Are there critical

key species in the food web? If substantial numbers of species are lost, will they be recovered when

original conditions are restored?

Comprehensive species conservation requires preservation of species throughout their complete

geographic and habitat range and a consideration of patterns of variation. Conservation of plants

must also take animals into account. Continued evolution will involve the interaction of both internal and external factors at a range of levels right down to the individual, and even the genome. As a

result, there are a number of fundamental questions to consider when conserving species or special

vegetation types in protected areas:





























Should protected areas be selected on the basis of strict biogeographic criteria?

Can existing protected areas be upgraded to improve their conservation effectiveness?

Are several small reserves better than one large one?

The minimum viable population (MVP) debate—how large does the population have to

be to be viable, and does MVP differ widely for different species?

How is protection integrated with traditional uses of plants?

How can plant conservation best be integrated with local people’s development aspirations and wealth generation?

How can we involve local stakeholders in the management of protected areas?

How do we protect a mosaic of many habitat types which may be necessary for life history

stages, or to conserve the full habitat needs of key pollinators and dispersers?

Should priority be given to protection of representative areas, or of areas with high levels

of species richness or unique vegetation types?

What strategies will best protect genetic diversity within populations?

If we simply protect representative ecosystems, are all species adequately protected along

with them?

What management and monitoring regimes should be implemented?

Should there be routine provision for harvesting target plants in the protected area for sustainable use or for germplasm?



Conservation of Wild Plants • 395



Most people accept the validity of these questions, but justifiably argue that one usually has to be

pragmatic. Social and economic issues may be sensitive, especially where dense human habitation

or questions of traditional use exist. Final boundary placement may have to be a compromise of

financial and political factors, existing patterns of land ownership and use, and the practical availability of sites for preserves.

When people think of protected areas, the first thing that often comes to mind is the National

Park System. These have wide international recognition as “jewels in the conservation crown.” They

enjoy a high public profile and are often large, preserving extensive ecosystems. But they may be too

large to facilitate management of highly endangered species. They are also public areas, in that traditionally people have reasonably unconstrained access. On the other hand, strict nature reserves

are well suited for conservation of individual species and smaller ecosystems. Yet, neither may meet

the needs of relict stands of vegetation growing in highly modified, urban habitats, or the requirements of genetic resource conservation.

The UNESCO Man and the Biosphere programme have drawn attention in many countries to

the need for a range of habitat types, from core areas that are close to a natural state, through

transition zones, seres, and ecotones, to human-influenced lands. Particularly valuable is the

concept of buffer zones bounding protected areas, and the range of mechanisms that can be used

to protect nature values on production lands, including land management agreements and conservation covenants.

Sites not specifically protected for nature conservation may have high conservation value and

reasonable permaneance. Examples include sacred sites such as churchyards and temples, railway or motorway embankments, lighthouse reserves, and military sites. In the United Kingdom

burial grounds and churchyards are sometimes extremely valuable for protection of wildflowers

that have all but disappeared from the countryside. There is an increasing need to think laterally

when considering sites for conservation of natural vegetation and native species. Even sports

and recreation grounds and racecourses are known to provide protection for populations of

threatened plants. Management may not be simple on such sites. Competing uses have to be

carefully meshed with conservation needs and there are likely to be conflicts that require compromise solutions.

Preserving biotic communities is not the same as preserving genes. Since communities are classified according to vegetation structure, and the dominant plant and animal keystone species, it is

quite possible to preserve a community-type and still lose many species. It is also possible to preserve a species and lose genetically distinct populations. Although on-site conservation requires

that biological diversity be considered as a whole—that is, in the form of intact communities—the

type of conservation strategies employed and their outcome will depend on the particular focus.

A protected area may concentrate on conserving a particular ecosystem, such as the Peat Swamp or

Heath Forests of Malaysia, Terra Firme forest in Amazonia, or Scalesia forest on the Galapagos

Islands. It may be focused on a particular and important tree species of one of those communities,

such as Gonostylus bancanus found in the Peat Swamp Forests or Lippia growing in Scalesia forest.

A protected area may also be established to conserve genetically distinct populations of such species, rather than the whole range of variation.

It is often assumed that conventional reserves to protect species and habitats are sufficient to

conserve all aspects of biological diversity. This ignores the particular needs of genetic resource conservation concerned with crop relatives and wild species with economic value. The aim of genetic

resource conservation is to maintain as many as possible of the genes or groups of genes found in

these species in a representative array of combinations (Prescott-Allen and Prescott-Allen 1986).

A special kind of protected area is an in situ (on-site) genetic reserve, which is a location where

wild genetic resources are conserved by maintaining gene pools of species in their natural habitat.



396 • The Cultural History of Plants



The emphasis is on species of known or potential economic value, and a necessary function is to

provide for use of the gene pool. There are two important distinctions between management for

gene pool conservation and management for other types of conservation. First, the unit of management is the gene pool rather than the species, community, or ecosystem. Second, provisions must

be made for collection and sustainable use of plants from the reserve by bona fide breeders and

research workers, and for supply of germplasm to ex situ gene banks.

These are the first steps for effective genetic resource conservation in natural habitats:

1. Select target taxa or region and undertake an ecogeographic survey to establish foci of

genetic diversity for the taxa. This will determine where the reserve could be located

within the region.

2. Survey potential sites for the genetic reserve and select the reserve site(s) based on scientific, economic and practical factors. Sites already under some form of protection, or in

common ownership, are likely to be most easily converted to genetic reserves.

3. Establish working relationships between protected area managers, major users (such as

plant breeders, geneticists, population biologists, and ethnobotanists), local traditional

resource users, and the local community. This provides a range of expertise to carry out

steps 2 and 4.

4. Complete a more detailed survey of population status, ecology, and life history of the target taxa within the genetic reserves.

5. Establish the management and monitoring regime for the genetic reserve that promotes

the retention of genetic diversity within the reserve.

6. Use the routine genetic reserve monitoring to feedback into the reserve management

regime.

7. Promote use of the reserve and the value resource by professional and traditional users,

while ensuring use does not adversely impact genetic diversity of the target taxa.

8. Establish a link with ex situ conservation to ensure any unique genetic diversity is duplicated to ensure security.

An in situ gene bank may be a formally designated protected area such as a nature reserve. It may

be a zone designated within a protected area that has other objectives, such as a national park.

It may be a protected area specifically set aside with genetic resource conservation as its only purpose. Where there is competition among different users of land wanted for a gene bank, there may

have to be careful selection so that adequate gene pools are protected in relatively few sites. Once

organized, a national system of genetic reserve will include an array of different types of protected

areas (Prescott-Allen and Prescott-Allen 1986):

1. Protected areas with many objectives, and some parts zoned for gene pool conservation. It

is logical that existing protected areas are candidates for consideration as pilot genetic

reserves.

2. Protected areas whose objectives do not permit artificial maintenance of seres (a developmental series of communities following in succession to a climax stage) or subclimaxes, but instead conserve climax species through protection of ecosystems in their

natural state.

3. Protected areas whose primary objective is gene pool conservation.

The distribution of protected areas should be such that they conserve at least one viable population of each major genetic variant of the target species. Protected populations must be sufficiently

viable as to be self-sustaining, and so minimize the loss of genes that only occur in low frequency.



Conservation of Wild Plants • 397



Those sites which have the highest numbers of target populations must be a priori for more detailed

investigation and monitoring. It will be necessary to ensure that plant numbers are sufficient to

maintain long-term populations, critical habitats are identified, essential associates such as pollinators and fruit dispersers are present, and other activities in the area do not jeopardize ex situ functions (MacKinnon et al. 1986). This is where it becomes essential to determine key biological

parameters, such as minimum viable population size, natural, and induced fluctuations in the population, and interactions with co-existing species.

Between two areas of very dissimilar habitat or land use, there will be a transition zone where the

habitats or land use interact as edge effects. Edge effects have two main consequences. In very small

reserves, there is a risk of the whole reserve being subject to edge effects so that no undisturbed core

remains; it becomes important to determine not only preferences of target species for core or noncore habitats, but also the preferences of inter-related organisms, such as pollinators. The concept

has been particularly developed for the boundary between land grossly disturbed by people and

predominantly natural habitat.

A widely adopted technique for minimizing edge effects and maintaining core areas is to establish

buffer zones around reserves. Buffer zones are areas peripheral to national parks or reserves which

have restrictions placed on their use to give an added layer of protection to the nature reserve itself,

and to compensate villagers for the loss of access to strict reserve areas (MacKinnon et al. 1986).

There is considerable scope for protected areas and buffer zones for plant conservation to also

help local people in a very practical way. Economic poverty of many tropical countries is aggravated

by the adoption of new and inappropriate agro-silvicultural systems. Many traditional systems of

agriculture (for example, multicrop and agroforestry systems) have evolved to minimize environmental impact. Their displacement can be disastrous. Protected areas are not only living laboratories for science and benchmarks against which to assess change; they can also offer valuable

facilities, especially in buffer zones, for education and awareness programs, and for research into

low-impact systems of land-use.

Local people may not have a profound understanding of modern conservation objectives, but

there are many examples of traditional cultural practices that have themselves led to the protection of ecosystems and species. Where local practices such as type, timing, and intensity of harvesting are compatible with long-term conservation, management should aim to incorporate them.

Other uses of plants by local people may have to be modified, especially where there are increasing demands on grazing land, fuelwood, or food plants. Necessary changes should be introduced

at a pace that allows people to adapt and understand. Examples include progressing from wild

harvest to sustainable cultivation of such crops as African ginger in South Africa and bulbs in

Turkey. Common concerns provide a basis for dialogue to develop a system of management that

will conserve plants and their environment, yet not alienate people. Local preference in employment is also an excellent way to integrate protected areas into the community and benefit people

in the immediate vicinity. A high proportion of locally-generated wealth should be shown to

directly benefit communities immediately adjacent to, and perhaps otherwise disadvantaged by,

a protected area.

Managing protected areas does not come free. It can usually be assumed that costs of management are more likely to escalate than decrease. In too many instances, management has come to

a standstill because it was assumed that necessary resources would become available or would not

cost. Similarly, it is tempting to keep adding new protected areas into a system, but each time this

happens it is necessary to budget not only for setting up a reserve (land purchase, fences, signs,

etc.), but also for continued management. Cuts in research funding too often occur in those areas

that are of most value to the conservation of plants, including population biology and monitoring.

These are not seen as revenue earning, and monitoring in particular is open to criticism as being



398 • The Cultural History of Plants



“open-ended”. Funding must be sufficient to carry out the minimum necessary activities to maintain a viable conservation program.

Translocation and Re-establishment of Threatened Species

The subject of translocations (transfers of species of animals and plants to other areas for conservation purposes by humans) generates strong opinions and feelings. Some conservationists and protected area managers regard translocations as unreasonable or not necessary, while others see it as a

routine protection mechanism fundamental to the survival of some critically threatened species.

One point to consider is that translocations are not new, but have been occurring for centuries.

Many prehistoric translocations took place as peoples moved across continents and oceans, taking

with them such plants as the coconut and sweet potato.

Translocations for conservation purposes are essential when habitat is about to be destroyed in

its entirety, and the only choice is either to allow plants to be destroyed or to shift them. Sometimes it is possible to shift plants from a site into a holding area on a temporary basis while rehabilitation is being done. In other instances, the shift may have to be permanent. Translocation may

also be justified where uncontrollable disease or predation threatens a population, or where for

species that are unable to breed sexually (usually through loss of one sexual state). By translocating plants from two or more sites to combine elements of them at one location, a new breeding

population can be established.

Several precautions are necessary, especially where translocations involve long distances and different climates or soils. Here there is a risk that the target species become weeds at the new site.

Accidental disease transfer must be avoided, especially where isolated target sites such as oceanic

islands are involved. Such places may not have the normal complement of pests and diseases, especially microrganisms. Careful documentation and follow-up is essential with a monitoring program

that can track any failures and set-backs and allow them to be rectified. Genetic considerations suggest that the variability of a population established at a new site should not be lower than that of the

source site. Properly done, translocations are time-consuming and can also be expensive, so they

should only be used where absolutely necessary.

The Role of ex situ Conservation

The general goal of conservation is the maintenance of viable populations of all species, preferably in the wild, where they can engage in a full range of interactions with other species and

the abiotic environment, as well as continuing to evolve. However, conservation managers and

decision-makers have to adopt a realistic approach to what is feasible as the threats to species

in situ continue to grow. Already much biodiversity lives in human-modified environments.

Many threats, which include habitat loss, climate change, unsustainable use, political instability, and invasive and pathogenic organisms, are difficult to control. The present reality is that

we shall be unable to ensure the survival of as many species as possible without significant use

of ex situ conservation, both as a primary conservation strategy and for back-up of in situ

conservation.

If the decision to bring a species under ex situ management is left to the last minute, it is frequently too late to implement effectively, and risks permanent loss of the species. However, ex situ

conservation should only be considered as an alternative to in situ conservation in the most exceptional circumstances (such as complete and sudden destruction of all wild habitat for a species),

and effective integration between in situ and ex situ approaches should be sought wherever possible.

What is also needed is to match good theory with effective practice, adopting the best methods and

philosophy for the particular situation. Ex situ conservation should not be adopted simply because

it is a last-minute act of desperation.



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20 Conservation of Wild Plants - DAVID R. GIVEN AND NIGEL MAXTED

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