T he main reasons for this crisis are welldocumented. The world’s tropical forests aredisappearing at an alarming rate, both due

to logging for the timber trade (much of it illegal) andto land conversion to agriculture. Vast tracts oflowland forest have been converted to banana, oilpalm or pineapple plantations. Large areas of theAmazon Basin are currently being converted to soyacultivation or pasture for cattle ranching.

What is not always appreciated is that many of the world’s temperate forests face a similar threat.Increased logging is taking place in the far east of Rus-sia, for example, and clear felling is continuing alongstretches of the northwestern coast of North America.

The potentially harmful effects of global warmingare of increasing concern. As average temperaturesrise, habitats may change and become unsuitable fortheir resident plants and animals. To survive, manyneed to migrate to more suitable areas, but habitatfragmentation means that such species may literallyhave nowhere else to go.

The island of Mauritius is a tropical paradise. Mostvisitors do not realise that only around 1% of itsoriginal forest remains. The lush green forest canopyis largely made up of introduced exotic species —guava and privet. Invasion by exotic species is anincreasing menace to natural populations. Of course,Mauritius was once home to the dodo, tragicallyextinct within less than 100 years of its discovery in 1598.

Sadly, examples of illegal and unsustainable huntingof animals for local trade and consumption, as well as for the international market, are easy to find. InChina there is an illegal market in snow leopard skinsand bones. The bones are used in traditional medicines,as are the gall bladders of bears. In parts of Africa where there is a shortage of protein, there is a thrivingbush meat trade, including such wild animals as chimpanzees.

Habitatfragmentation: afterclearing the naturalvegetation in an area,small fragments of the originallandscape aresometimes allowed toremain. Unfortunately,the number of speciesable to survive in suchsmall parcels of landdeclines rapidly.

Plant migration: unlikeanimals, plants have toremain rooted to thespot. Plant populationscan, however, migrateover time through seeddispersal.

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Philip Seaton

GCSE key wordsHuman impact onthe environment

DeforestationGlobal warming

Life in the balance?Much of our planet’s biodiversity appears to be teetering on the brink of a man-madeextinction crisis. Scientists have suggested that, unless urgent action is taken now, manyspecies will disappear in the next 50 years.This article looks at some of the issuesinvolved.

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l To learn more aboutOrchid ConservationInternational go to its website (www.orchidconservation.org).

2 Catalyst

Box 1 Case study: a Kew expedition to MadagascarDuring our 11-hour drive to the RanamofanaNational Preserve it was easy to believe that only10% of Madagascar’s natural forest remains. Formost of the journey the countryside was a mosaicof rice paddies encircled by bare hillsides with theircharacteristic red soils which, from the air, can beseen bleeding into the surrounding Indian Ocean.

The lush humid forest of Ranamofana boasts atotal of 20 lemur species, each living in a slightlydifferent ecological niche. The highlight was finding the rare golden bamboo lemur. Only 100 individuals remain in the wild, 20 of which are currently protected, at Ranamofana.

In contrast, the Itremo Plateau was hot and dry.We were looking for plants of an endangeredorchid, Angraecum longicalcar, which grows in fullsun on marble outcrops. We soon discovered thatthe total population had declined to no more than 25 plants. The local herdsmen routinely burn thegrassland, to stimulate the formation of fresh greenshoots for their herds of zebu cattle. Alarmingly,part of the population of orchids had recently beenaccidentally burned. In addition, some of theremaining plants had been removed by collectors,and one of the outcrops was being mined for itsmarble. Truly, this is an orchid species on the edge.

Figure 1 Mauritiusand Madagascar areislands in the IndianOcean

Phil’s colleague David Roberts from Kew locatingthe Angraecum longicalcar in Madagascar

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Why should we care?There are various reasons why we should beconcerned. The first is an economic argument. Illegallogging threatens the livelihoods of many localcommunities that depend on forest resources foremployment and income. Trees bind the soil togetherand, particularly on steep slopes, prevent it beingwashed away by rainfall.

Plants and animals are important sources of food,fibres and, potentially, undiscovered medicines.

At the heart of the matter is the fact that we dependon other species for our continued existence on thisplanet. They are part of the fabric of life, and foodchains and food webs may begin to unravel as keyorganisms are removed.

Ultimately, after millions of years of evolution andcoexistence, many people would argue that it ismorally wrong to cause the extinction of plants andanimals.

What is being done?All of the above can make pretty depressing reading,but fortunately there appear to be an increasingnumber of people who care enough to be doingsomething, and more and more people are willing topay to see wildlife in its natural habitat. The CentralAmerican country of Costa Rica, for example, derivesmore income from ecotourism than any other source.Here are just a few examples of the sorts of conser-vation activities and projects that are taking placearound the world.

Mauritius kestrelIn situ conservation involves conservation of plantsand animals in their natural habitats. The Mauritiuskestrel declined to just four wild individuals, butcaptive breeding and subsequent reintroduction hassaved this beautiful bird from extinction.

African elephantsOne of the successes of the conservation communityhas been the international agreement banning tradein ivory and its products, thereby halting the lucrativemarket for poached tusks, and the catastrophicdecline in African elephant populations.

Lady’s slipper orchidIt is not only plants and animals in exotic places thatare at risk. In Britain our native lady’s slipper orchiddeclined to one individual plant remaining in a secretlocation somewhere in Yorkshire, after the plants hadbeen dug up by collectors. Artificial pollinations werecarried out by staff at the Royal Botanic Gardens,Kew, the seeds germinated in the micropropagationunit, and a healthy population of seedlings was onceagain established in its natural habitat.

Sustainable developmentEx situ conservation is conservation of materialoutside its natural habitat.

The key phrase in the vocabulary of today’s conser-vationists is sustainable development. In Mexicomany orchid species are used in religious festivals todecorate the altars. Not only are the flowers removedfrom the wild, but also sections of the plants, as thismeans that the flowers will remain fresh for a longertime. This leads to a decline in natural populations.

Projects are now being set up to store seed of theseorchids for the future in germ banks, and laboratoriesare being established to raise orchids from seed for subsequent cultivation by the local people. TheMillennium Seed Bank Project at Kew aims toconserve seeds representing 10% of the world’s flora by 2010, concentrating particularly on semi-arid areas, where most people live on land on which agriculture is marginal.

Philip Seaton taught biology for more than 30 years. He now works full time in orchid conservation. He is secretary to the Orchid Specialist Group of the IUCN/SSC, the WorldConservation Union, and Orchid Conservation International, aRegistered Charity.

The natural vegetationof much of Britain iswoodland, but mostforests were cleared foragriculture thousandsof years ago.

l The beautiful blueBrazilian parrot, Spix’smacaw, was declaredextinct in the wild inDecember 2000. Incontrast, after anabsence of more than60 years, the ivory-billed woodpecker hasrecently been sighted inthe ancient cypressswamps of Arkansas,USA. To learn moreabout both birds go towww.arkive.org/species

l To find out moreabout the MillenniumSeed Bank Project visitthe Kew website onwww.kew.org.uk andclick on WakehurstPlace.

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Box 2 Case study: cloud forests ofCosta RicaCloud forests are among the richest habitats onEarth. Constantly bathed in rain and mist, thebranches of the trees are draped in a dense carpetof orchids, bromeliads and ferns. As globaltemperatures rise so the cloud base moves up themountain sides, and those plants and animalsmigrate up the mountains along with the changingconditions. Those that required the specialconditions at the tops of the mountains havenowhere left to go.

A lady’s slipper orchid

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