What is Biodiversity?
Biodiversity is a modern term which simply means " the variety of life on earth". This variety can be measured on several different levels.
Genetic - variation between individuals of the same species. This includes genetic variation between individuals in a single population , as well as variations between different populations of the same species. Genetic differences can now be measured using increasingly sophisticated techniques. These differences are the raw material of evolution.
Species - species diversity is the variety of species in a given region or area. This can either be determined by counting the number of different species present, or by determining taxonomic diversity. Taxonomic diversity is more precise and considers the relationship of species to each other. It can be measured by counting the number of different taxa (the main categories of classification) present. For example, a pond containing three species of snails and two fish, is more diverse than a pond containing five species of snails, even though they both contain the same number of species. High species biodiversity is not always necessarily a good thing. For example, a habitat may have high species biodiversity because many common and widespread species are invading it at the expense of species restricted to that habitat.
Ecosystem - Communities of plants and animals, together with the physical characteristics of their environment (e.g. geology, soil and climate) interlink together as an ecological system, or 'ecosystem'. Ecosystem diversity is more difficult to measure because there are rarely clear boundaries between different ecosystems and they grade into one another. However, if consistent criteria are chosen to define the limits of an ecosystem, then their number and distribution can also be measured.
How many species are there?
Estimates of global species diversity vary enormously because it is so difficult to guess how many species there may be in less well explored habitats such as untouched rain forest. Rain forest areas which have been sampled have shown such amazing biodiversity (nineteen trees sampled in Panama were found to contain 1,200 different beetle species alone!) that the mind boggles over how many species there might remain to be discovered in unexplored rain forest areas and microhabitats.
Global species estimates range from 2 million to 100 million species. Ten million is probably nearer the mark. Only 1.4 million species have been named. Of these, approximately 250,000 are plants and 750,000 are insects. New species are continually being discovered every year. The number of species present in little-known ecosystems such as the soil beneath our feet and the deep sea can only be guessed at. It has been estimated that the deep sea floor may contain as many as a million undescribed new species. To put it simply, we really have absolutely no idea how many species there are!
Losses of Biodiversity
Extinction is a fact of life. Species have been evolving and dying out ever since the origin of life. One only has to look at the fossil record to appreciate this. (It has been estimated that surviving species constitute about 1% of the species that have ever lived.)
However, species are now becoming extinct at an alarming rate, almost entirely as a direct result of human activities. Previous mass extinctions evident in the geological record are thought to have been brought about mainly by massive climatic or environmental shifts. Mass extinctions as a direct consequence of the activities of a single species are unprecedented in geological history.
The loss of species in tropical ecosystems such as the rain forests, is extremely well-publicised and of great concern. However, equally worrying is the loss of habitat and species closer to home in Britain. This is arguably on a comparable scale, given the much smaller area involved.
Predictions and estimates of future species losses abound. One such estimate calculates that a quarter of all species on earth are likely to be extinct, or on the way to extinction within 30 years. Another predicts that within 100 years, three quarters of all species will either be extinct, or in populations so small that they can be described as "the living dead".
It must be emphasised that these are only predictions. Most predictions are based on computer models and as such, need to be taken with a very generous pinch of salt. For a start, we really have no idea how many species there are on which to base our initial premise. There are also so many variables involved that it is almost impossible to predict what will happen with any degree of accuracy. Some species actually benefit from human activities, while many others are adversely affected. Nevertheless, it is indisputable that if the human population continues to soar, then the ever increasing competition with wildlife for space and resources will ensure that habitats and their constituent species will lose out.
It is difficult to appreciate the scale of human population increases over the last two centuries. Despite the horrendous combined mortality rates of two World Wars, Hitler, Stalin, major flu pandemics and Aids, there has been no dampening effect on rising population levels. In 1950, the world population was 2.4 billion. Just over 50 years later, the world population has almost tripled, reaching 6.5 billion.
In the UK alone, the population increases by the equivalent of a new city every year. Corresponding demands for a higher standard of living for all, further exacerbates the problem. It has been estimated that if everyone in the world lived at the UK standard of living (and why should people elsewhere be denied this right) then we would either need another three worlds to supply the necessary resources or alternatively, would need to reduce the world population to 2 billion.
The only possible conclusion is that unless human populations are substantially reduced, it is inevitable that biodiversity will suffer further major losses.
Some species are more vulnerable to extinction than others. These include:
Why Conserve Biodiversity?
Ecological Reasons
Individual species and ecosystems have evolved over millions of years into a complex interdependence. This can be viewed as being akin to a vast jigsaw puzzle of inter-locking pieces. If you remove enough of the key pieces on which the framework is based then the whole picture may be in danger of collapsing. We have no idea how many key 'pieces' we can afford to lose before this might happen, nor even in many cases, which are the key pieces. The ecological arguments for conserving biodiversity are therefore based on the premise that we need to preserve biodiversity in order to maintain our own life support systems.
Two linked issues which are currently of great ecological concern include world-wide deforestation and global climate change.
Forests not only harbour untold numbers of different species, but also play a critical role in regulating climate. The destruction of forest, particularly by burning, results in great increases in the amount of carbon in the atmosphere. This happens for two reasons. Firstly, there is a great reduction in the amount of carbon dioxide taken in by plants for photosynthesis and secondly, burning releases huge quantities of carbon dioxide into the atmosphere. (The 1997 fires in Indonesia’s rain forests are said to have added as much carbon to the atmosphere as all the coal, oil and gasoline burned that year in western Europe.) This is significant because carbon dioxide is one of the main greenhouse gases implicated in the current global warming trend.
Average global temperatures have been showing a steadily increasing trend. Snow and ice cover have decreased, deep ocean temperatures have increased and global sea levels have risen by 100 - 200 mm over the last century. If current trends continue, scientists predict that the earth could be on average 1oC warmer by 2025 and 3oC warmer by 2100. These changes, while small, could have drastic effects. As an example, average temperatures in the last Ice Age were only 5oC colder than current temperatures.
Rising sea levels which could drown many of our major cities, extreme weather conditions resulting in drought, flooding and hurricanes, together with changes in the distribution of disease-bearing organisms are all predicted effects of climate change.
Forests also affect rainfall patterns through transpiration losses and protect the watershed of vast areas. Deforestation therefore results in local changes in the amount and distribution of rainfall. It often also results in erosion and loss of soil and often to flooding. Devastating flooding in many regions of China over the past few years has been largely attributed to deforestation.
These are only some of the ecological effects of deforestation. The effects described translate directly into economic effects on human populations.
Economic Reasons
Environmental disasters such as floods, forest fires and hurricanes indirectly or directly caused by human activities, all have dire economic consequences for the regions afflicted. Clean-up bills can run into the billions, not to mention the toll of human misery involved. Susceptible regions are often also in the less-developed and poorer nations to begin with. Erosion and desertification, often as a result of deforestation, reduce the ability of people to grow crops and to feed themselves. This leads to economic dependence on other nations.
Non-sustainable extraction of resources (e.g. hardwood timber) will eventually lead to the collapse of the industry involved, with all the attendant economic losses. It should be noted that even if 'sustainable' methods are used, for example when harvested forest areas are replanted, these areas are in no way an ecological substitute for the established habitats which they have replaced.
Large-scale habitat and biodiversity losses mean that species with potentially great economic importance may become extinct before they are even discovered. The vast, largely untapped resource of medicines and useful chemicals contained in wild species may disappear forever. The wealth of species contained in tropical rain forests may harbour untold numbers of chemically or medically useful species. Many marine species defend themselves chemically and this also represents a rich potential source of new economically important medicines. Additionally, the wild relatives of our cultivated crop plants provide an invaluable reservoir of genetic material to aid in the production of new varieties of crops. If all these are lost, then our crop plants also become more vulnerable to extinction.
There is an ecological caveat here of course. Whenever a wild species is proved to be economically or socially useful, this automatically translates into further loss of natural habitat. This arises either through large-scale cultivation of the species concerned or its industrial production/ harvesting. Both require space, inevitably provided at the expense of natural habitats.
Perhaps the rain forests and the seas should be allowed to keep their secrets.
Ethical Reasons
Do we have the right to decide which species should survive and which should die out?
Do we have the right to cause a mass extinction?
Most people would instinctively answer 'No!'. However, we have to realise that most biodiversity losses are now arising as a result of natural competition between humans and all other species for limited space and resources.
If we want the luxury of ethics, we need to reduce our populations.
Aesthetic Reasons
Most people would agree that areas of vegetation, with all their attendant life forms, are inherently more attractive than burnt, scarred landscapes, or acres of concrete and buildings. Who wouldn't prefer to see butterflies dancing above coloured flowers, rather than an industrial complex belching smoke?
Human well-being is inextricably linked to the natural world. In the western world, huge numbers of people confined to large urban areas derive great pleasure from visiting the countryside. The ability to do so is regarded not so much as a need, but as a right. National governments must therefore juggle the conflicting requirements for more housing, industry and higher standards of living with demands for countryside for recreational purposes.
How do we Conserve Biodiversity?
There are two main ways to conserve biodiversity. These are termed ex situ (i.e. out of the natural habitat) and in situ (within the natural habitat)
Ex Situ Conservation - out of the natural habitat
(Species-based)
In the past, zoos were mainly display facilities for the purpose of public enjoyment and education. As large numbers of the species traditionally on display have become rarer in the wild, many zoos have taken on the additional role of building up numbers through captive breeding programmes.
Although comparatively far more invertebrates than vertebrates face extinction, most captive breeding programmes in zoos focus on vertebrates. Threats to vertebrate extinction tend to be well publicised (e.g. Dormouse, Panda). People find it easier to relate to and have sympathy with animals which are more similar to ourselves, particularly if they are cute and cuddly (at least in appearance, if not in fact!). Not many visitors to zoos are likely to get excited over the prospect of the zoo 'saving' a tiny beetle, which they can barely see, let alone spiders or other invertebrates which often invite horror rather than wonder. Vertebrates therefore serve as a focus for public interest. This can help to generate financial support for conservation and extend public education to other issues. This is a very important consideration, as conservation costs money and needs to be funded from somewhere.
The focus on vertebrates is not solely pragmatic. Many of the most threatened vertebrates are large top carnivores, which the world stands to lose in disproportionate numbers. Such species require extensive ranges to provide sufficient prey to sustain them. In many cases, whole habitats for these predators have all but disappeared. Some biased expenditure on their survival may therefore be justified.
Several species are now solely represented by animals in captivity. Captive breeding programmes are in place for numerous species. At least 18 species have been reintroduced into the wild following such programs. In many cases the species was actually extinct in the wild at the time of reintroduction (Arabian Oryx, Pere David Deer, American Bison). In some cases, all remaining individuals of a species, whose numbers are too low for survival in the wild, have been captured and the species has then been reintroduced after captive breeding (California Condor).
The role of zoos in conservation is limited both by space and by expense. At population sizes of roughly 100-150 individuals per species, it has been estimated that world zoos could sustain roughly 900 species. Populations of this size are just large enough to avoid inbreeding effects. However, zoos are now shifting their emphasis from long-term holding of species, to returning animals to the wild after only a few generations. This frees up space for the conservation of other species.
Genetic management of captive populations via stud records is essential to ensure genetic diversity is preserved as far as possible. There are now a variety of international computerised stud record systems which catalogue genealogical data on individual animals in zoos around the world. Mating can therefore be arranged by computer, to ensure that genetic diversity is preserved and in-breeding minimised (always assuming the animals involved are prepared to co-operate).
Research has led to great advances in technologies for captive breeding. This includes techniques such as artificial insemination, embryo transfer and long-term cryogenic (frozen) storage of embryos. These techniques are all valuable because they allow new genetic lines to be introduced without having to transport the adults to new locations. Therefore the animals are not even required to co-operate any longer. However, further research is vital. The success of zoos in maintaining populations of endangered species is limited. Only 26 of 274 species of rare mammals in captivity are maintaining self-sustaining populations.
Reintroduction of species to the wild poses several different problems.
The role of aquaria has largely been as display and educational facilities. However, they are assuming new importance in captive breeding programmes. Growing threats to freshwater species in particular, are leading to the development of ex situ breeding programmes. The World Conservation Union (IUCN) is currently developing captive breeding programmes for endangered fish. Initially this will cover those from Lake Victoria in Africa, the desert fishes of N. America and Appalachian stream fishes. Natural habitats will be restored as part of the programme.
Marine, as well as freshwater species are also the subject of captive breeding programmes. For example, The National Marine Aquarium, in South West England, is playing an important role in the conservation of sea horse species through their captive breeding programme.
PLANT COLLECTIONS
Populations of plant species are much easier than animals to maintain artificially. They need less care and their requirements for particular habitat conditions can be provided more readily. It is also much easier to breed and propagate plant species in captivity.
There are roughly 1,500 botanic gardens world-wide, holding 35,000 plant species (more than 15% of the world’s flora). The Royal Botanic Gardens of England (Kew Gardens) contains an estimated 25,000 species. IUCN classifies 2,700 of these as rare, threatened or endangered. Many botanic gardens house collections of particular taxa which are of major conservation value. There is however, a general geographic imbalance. Only 230 of the world’s 1,500 gardens are in the tropics. Considering the greater species richness of the tropics, this is an imbalance that needs to be addressed.
A more serious problem with ex situ collections involves gaps in coverage of important species, particularly those of significant value in tropical countries. One of the most serious gaps is in the area of crops of regional importance, which are not widely traded on world markets. These often have recalcitrant seeds (unsuited to long-term storage) and are poorly represented in botanic collections. Wild crop relatives are also under-represented. These are a potential source of genes conferring resistance to diseases, pests and parasites and as such are a vital gene bank for commercial crops.
Plant genetic diversity can also be preserved ex situ through the use of seed banks. Seeds are small but tough and have evolved to survive all manner of adverse conditions and a host of attackers. Seeds can be divided into two main types, orthodox and recalcitrant. Orthodox seeds can be dried and stored at temperatures of -20oC. Almost all species in a temperate flora can be stored in this way. Surprisingly, many tropical seeds are also orthodox. Recalcitrant seeds, in contrast, die when dried and frozen in this manner. Acorns of oaks are recalcitrant and it is believed that so are the seeds of most tropical rain forest trees.
The result of storing seeds under frozen conditions is to slow down the rate at which they lose their ability to germinate. Seeds of crop plants such as maize and barley could probably survive thousands of years in such conditions, but for most plants, centuries is probably the norm. This makes seed banking an attractive conservation option, particularly when all others have failed. It offers an insurance technique for other methods of conservation.
All of the ex situ conservation methods discussed have their role to play in modern conservation. Generally, they are more expensive to maintain and should be regarded as complementary to in situ conservation methods. For example they may be the only option where in situ conservation is no longer possible.
In Situ Conservation - within the natural habitat
(Habitat or species-based)
Protected sites, or Reserves
In situ conservation maintains not only the genetic diversity of species, but also the evolutionary adaptations that enable them to adapt continually to shifting environmental conditions, such as changes in pest populations or climate. In situ conservation also ensures that along with target species, a host of other interlinked species are also preserved as a by-product. It is generally cheaper than ex situ methods (although not cheap). It may often be the only conservation option, for example for species with recalcitrant seeds.
In situ conservation measures involve designating specific areas as protected sites. Protection may be offered at various levels, from complete protection and restriction of access, through various levels of permitted human use. In practice, complete protection is rarely necessary or advisable in a terrestrial context. Human beings have been a major part of the landscape for many thousands of years. Over the course of that time, human cultures have emerged and adapted to the local environment, discovering, using and altering biotic resources. Many areas that now appear ‘natural’ bear the hallmarks of millennia of human influence. Other species have evolved along with that influence and in many cases require the disturbance provided by humans to provide the necessary conditions for their survival. In other words, it is rarely advisable to relegate the countryside to the status of a museum piece.
This applies particularly in the less economically developed areas of the world, where in many cases, the livelihood of the local people depends on using the natural resources available to them. Prohibiting the use of such resources in protected areas means that expensive enforcement measures usually have to be put in place. It is far better to involve local people in conservation and to find creative ways for them to make a sustainable living while still protecting valuable habitats or species.
The biosphere reserve concept has been developed through the Man and Biosphere (MAB) Programme of the United Nations Educational, Scientific and Cultural Organisation (UNESCO). Biosphere reserves are an attempt to reconcile the problems of conserving biodiversity and biological resources, with sustainable use of natural resources for people. They form an international network of sites, nominated by national governments, but designated by UNESCO. The first reserves were nominated as long ago as 1976. By 2001, a network of 393 reserves in 94 countries had been developed.
Marine conservation areas lag behind terrestrial ones. Protected areas have existed on land for over a century, but there is no tradition of managing marine areas for conservation. The only current statutory marine reserve in England is Lundy Island. This harbours a huge variety of marine life due to the diversity of underwater habitats present there.
Marine reserves may be vital tools in preserving species-rich areas such as tropical coral reefs, which are being devastated by non-sustainable fishing methods in many areas. The rationale of such reserves is not to lock away fish from fishermen, but rather to create refuges inside which populations can build up and spill over to repopulate adjacent areas.
Marine Reserves need to be carefully designed to take into account, movement patterns, dispersal rates and population dynamics of particular target species. For example, it would be pointless having a reserve where the resident species regularly travelled to non-protected areas. It would also be pointless protecting the habitat of an adult, but neglecting the geographically different breeding grounds and habitats of juveniles, or vice versa. Such factors should also be taken into consideration in the design of terrestrial reserves.
Management of Nature Reserves
Nature reserves are usually designated to protect a particular species, assemblage of species, or specific habitats. As such they can rarely be left in isolation to manage themselves. Management is necessary in order to prevent natural processes such as succession from taking place. Such resulting changes in habitat may mean the loss of particular species for which the reserve was originally designated.
Succession is a natural process which will tend to replace particular species with different ones. This is often as a result of ecological change induced by the organisms themselves. In former times, while an area of a particular habitat might be lost through succession (such as a wetland drying out and eventually becoming a woodland), there would always be other wetland habitats at an earlier stage of the succession process elsewhere. These would act as species reservoirs. With the drastic loss of area of natural habitat occurring world-wide, this is often no longer the case. The decision therefore has to be made to halt succession at a particular stage in order to preserve the species associated with it. Examples of this include wild flower meadows, wetlands and heathlands.
RESTORATION
Restoration attempts to bring land modified by human use back to its original state. Because determining the original natural state is often difficult and because ecosystems continually change, this is rarely a realistic goal. Changes may also in some cases be irreversible, so that restoration to an original condition is not an option. For these reasons, restoration is often limited to the approximate recreation of habitat.
Restoration does not necessarily require intervention. Left to natural processes, many ecosystems will return to their original condition provided populations of the original species still exist nearby. This may however be a lengthy process. In Brazil’s caatinga forest, natural recovery of slash and burn agricultural sites takes more than a century. Sites cleared by bulldozer may take a thousand or more years to recover. Intervention may be used to speed up the process. It becomes vital where an ecosystem will never recover naturally, either because it has been physically transformed, or because species cannot migrate to repopulate the area. Restoration may rely heavily upon species maintained by ex situ methods and is an example of the complementary nature of in situ and ex situ techniques.
RECOVERY OF THREATENED SPECIES
The recovery of threatened species generally hinges on providing suitable habitat and conditions in which they can thrive. Most biodiversity losses can be directly attributed to habitat loss, so provision of habitat is often the key requirement for recovery of a species. The dormouse (Muscardinus avellanarius) is a good example of this.
Dormice are the subject of a species recovery program sponsored by English Nature. They thrive in deciduous woodland and overgrown hedgerows. They are arboreal and require networks of interlinking low branches to provide aerial highways to food sources (e.g. hazel nuts and honeysuckle). In former times, the practice of coppicing woodland (cutting trees near to ground level and then allowing them to regenerate numerous shoots) provided ideal conditions for dormice. However, coppicing is little practised these days, with the result that large areas of former habitat have become unsuitable for dormice. Recovery therefore hinges on providing suitable areas for the species.
Dormice also suffer from competition with an introduced species, the grey squirrel. Both species compete for the food resource of hazel nuts.
INTRODUCED SPECIES
The vast majority of exotic introduced species die out because they are unsuited to local conditions. A few however, appear to be superbly adapted to particular local conditions and will tend to out-compete native species.
Regulatory policies are necessary to curb the introduction of exotic species and genetic resources, as the consequences can be disastrous. Introduced species can wipe out innumerable other local species. Between 1967 and 1972, an African cichlid fish introduced into a lake in Panama wiped out 6 of the 8 previously common fish species, drastically reduced populations of a seventh and affected aquatic invertebrates, algae and fish-eating birds up and down the food chain.
In Britain, particularly in the west, rhododendron has taken over large areas, virtually eliminating native plants and their associated faunas. This one species alone has decimated tens of thousands of acres. Grey squirrels introduced from America have also all but replaced native red squirrel populations.
Even introducing the same species can present hazards through the mixing of genetic stocks. Fish populations can be contaminated by interbreeding with introduced varieties. The genetic integrity of native British Red Deer is now also threatened through hybridisation with introduced Sika Deer. Pure Red Deer may in the end be confined to isolated islands in Scotland.
GENETIC MODIFICATION
Humans now have the technology to alter life on earth in a totally unique way. Genetic engineering can involve the transfer of genetic material between widely separated taxonomic groups. e.g. Genes from a fish have been introduced into tomatoes. Entirely new species can intentionally or unintentionally be produced. There is no guarantee that all the results will be beneficial or can even be controlled.
LEGAL PROTECTION
Nature reserves need to be properly protected from the adverse results of human activity. This might be indirect, as in for example, habitat degradation through pollution brought about by activities elsewhere. Alternatively, it may involve direct damage, as in unauthorized extraction of resources from the reserve. Such protection requires the presence of a legal framework which can be effectively enforced.
Conservation at the National Level
National governments are vital to the preservation of biodiversity through the passing of laws requiring protection of species and habitats. If national laws do not protect species, then there is little hope of preserving them. However, it is not enough just to have laws, there must also be the will and the resources to enforce them. Even in economically developed nations, the necessary resources to properly enforce laws are not always made available. In under-developed nations, even the most basic resources for enforcement may be lacking. In addition, national laws may not in the end translate into local action, in which case they do not accomplish much. In democratic nations, national laws are also driven to a large extent by public opinion. They may in some cases be drafted more as a response to emotion than by actual scientific need.
Several international conventions exist for the preservation of biodiversity. These include such conventions as the Ramsar Convention (1976) which provides for the conservation of internationally important wetlands and the Bern Convention (1979) which requires the protection of endangered and vulnerable species of flora and fauna in Europe and their habitats. There are many others. Signatory nations to these conventions must ratify national laws to ensure compliance with the conventions.
In Britain, the main piece of legislation covering conservation is the Wildlife and Countryside Act 1981 and 1985, which implements preceding EU conventions. It protects both species and sites of UK importance. Enforcement of conservation directives is the responsibility of the Environment Agency, a government organisation. English Nature, a government funded watchdog, is also responsible for the promotion of the conservation of England’s wildlife.
In addition to the enforcement of laws, the Environment Agency is also responsible for data collection and monitoring. Environmental monitoring and biodiversity surveys are important because they provide information on the condition of ecosystems and the changes that are taking place within them. They therefore provide the scientific information on which to base environmental policy decisions. Similarly, assessments of the environmental impact of large development projects are vital before relevant authorities can either grant permission to proceed, or require that changes be made to development designs.
International Conservation
Species and ecosystems are seldom neatly confined within national boundaries. Many species roam across countless national borders and the oceans are owned by none. Trade in endangered species (or parts thereof) is international and pollution produced on one side of the world may wind up affecting regions on the other side of the globe. Biodiversity conservation is thus an international problem requiring international solutions.
The role of international conservation organisations is a vital one, particularly in terms of brokering international agreements between governments concerned with protecting their national interests. The most far-reaching agreement on biodiversity in recent years is the Convention on Biodiversity, signed by 156 nations at the United Nations Conference on Environment and Development ( the Earth Summit ) in Rio in 1992. Many others have signed since, and as they ratify the convention, governments accept responsibility for safeguarding biodiversity in their nations. Many international conservation organisations including WRI ( World Resources Institute ) and IUCN ( The World Conservation Union ) contributed to the formulation of the documents signed at the convention.
The UK was one of the first countries to follow up its commitment under the Convention on Biodiversity.
Biodiversity: The UK Action Plan was published in January 1994. A UK Biodiversity Steering Group was appointed , which published a report entitled Meeting the Rio Challenge in 1995. The report contains action plans for over 100 endangered species and 14 key habitats, together with a commitment to produce further plans. The Steering Group proposed the use of a standard methodology for the production of local biodiversity action plans. These would be based upon the priorities of the UK plan, but would be supplemented by local priorities.
Action Plans seek to apply principles of business planning to a strategic view of the environment. They identify objectives, set quantified targets and define the actions needed to reach those targets. The Nature of Devon - A Biodiversity Action Plan is Devon’s response to this national biodiversity planning process. This regional process is going on throughout England. The sum of all the regional Biodiversity Action Plans should add up to the full UK Biodiversity Action Plan.
International conservation organisations play an important role in the wide publicising of environmental information. IUCN was responsible for the idea of compiling lists of threatened species as a means of drawing attention to the plight of species faced with extinction. These lists became known as Red Data Books ( RDBs ). In these, species are placed into one of several categories which range from ‘extinct’ to ‘vulnerable’ or ‘rare’, depending on the degree of threat to their existence. The first internationally applicable RDB was published in 1996. The ‘red’ stands for ‘danger’ and the concept has since been adopted by many different countries, including Britain. RDBs point the way for government agencies charged with environmental protection, as well as for non-governmental organisations ( NGOs ) concerned about maintaining diversity.
Organisations such as WWF, founded in 1961 by Sir Peter Scott, the eminent naturalist, are highly effective in publicising the plight of endangered species world-wide. They also play a large role in raising charitable funds towards projects concerned with saving wildlife in various areas of the globe. Many such conservation organisations pay for the basic resources needed by under-developed countries to enforce their laws. This can be as basic as providing a means of transport and salaries for enforcement officers. However, how effective these campaigns and projects are in the long run remains to be seen. Loss of habitat is still the most pressing problem.
In some areas, biodiversity is seriously threatened as a result of trade in endangered species. The international trade in wildlife is estimated to be worth £12 billion a year. Up to a quarter of that trade is almost certainly illegal. The main piece of legislation limiting trade in endangered species is CITES (the Convention on International Trade in Endangered Species). This is a UN convention which came into effect in 1975. CITES prohibits commercial trade in endangered species of plants and animals. Legitimate international trade in species which are not now threatened, but which may become so if trade is not controlled, is allowed via a permit system. Responsibility for implementing it lies with signatory nations.
Many of the problems involved in protecting habitats and species arise because local people either need to use the resources available in sensitive habitats to provide the necessities for subsistence or survival, or traditionally have always done so. UNESCO (United Nations Educational, Scientific and Cultural Organisation), through its 'Man and the Biosphere' programme, has set up a number of Internationally recognised biosphere reserves in an attempt to address this problem.
Overview
The world has a vast range of different species which are all inextricably linked. The eminent naturalist and television presenter, Sir David Attenborough, summed this up neatly when he said "The inter-dependence of species evolved over millions of years and underpins the complex diversity of life which exists on this planet."
We can only guess at many of the interactions taking place within habitats. While we have come a long way in our knowledge of the natural world, we need to recognise that we are still fundamentally ignorant. With recognition of this ignorance comes the understanding that we need to preserve whole habitats intact, so that the complexity of interactions remains, whether we understand them or not.
The fate of the entire planet is now dependent upon a single species - humans. This is unprecedented in the Earth’s 4.7 billion year history. Ultimately, conservation of biodiversity will hinge upon the control of human populations. Continually expanding human numbers have led to an escalating competition with wildlife for the space required to house everyone, as well as to produce enough food to feed them. Increasing standards of living also require that further natural areas and resources are given over to sustaining western lifestyles and associated demands.
We are interfering with biodiversity on a great many levels, from the molecular (genetic modification), all the way through habitats and possibly global climate change as well. However, the many predictions made about species and habitats losses need to be carefully examined in each case and not just taken at face value. Many are based on computer simulations and emotions can get in the way of clear practical thinking.
Anyone concerned about conservation needs to question whether the innumerable strategies and policies in place are actually being delivered. International conventions and national laws are in the end only ideas on pieces of paper. These must be translated into concrete action in local situations for anything to be truly accomplished.
On the plus side, it is possible to restore some habitats which have been lost or degraded. This is not to imply that it is permissible to destroy habitats in the first place. This causes the local extinction of all the species in the habitat and it can take hundreds of years for complex ecosystems to become re-established. The species which have recolonised the restored habitat will also not necessarily be of the same genetic make-up as the original inhabitants.
However, restoration does mean that action can be taken to repair damage. The natural world given half a chance is amazingly resilient. All it needs is space and time.
Biodiversity is a modern term which simply means " the variety of life on earth". This variety can be measured on several different levels.
Genetic - variation between individuals of the same species. This includes genetic variation between individuals in a single population , as well as variations between different populations of the same species. Genetic differences can now be measured using increasingly sophisticated techniques. These differences are the raw material of evolution.
Species - species diversity is the variety of species in a given region or area. This can either be determined by counting the number of different species present, or by determining taxonomic diversity. Taxonomic diversity is more precise and considers the relationship of species to each other. It can be measured by counting the number of different taxa (the main categories of classification) present. For example, a pond containing three species of snails and two fish, is more diverse than a pond containing five species of snails, even though they both contain the same number of species. High species biodiversity is not always necessarily a good thing. For example, a habitat may have high species biodiversity because many common and widespread species are invading it at the expense of species restricted to that habitat.
Ecosystem - Communities of plants and animals, together with the physical characteristics of their environment (e.g. geology, soil and climate) interlink together as an ecological system, or 'ecosystem'. Ecosystem diversity is more difficult to measure because there are rarely clear boundaries between different ecosystems and they grade into one another. However, if consistent criteria are chosen to define the limits of an ecosystem, then their number and distribution can also be measured.
How many species are there?
Estimates of global species diversity vary enormously because it is so difficult to guess how many species there may be in less well explored habitats such as untouched rain forest. Rain forest areas which have been sampled have shown such amazing biodiversity (nineteen trees sampled in Panama were found to contain 1,200 different beetle species alone!) that the mind boggles over how many species there might remain to be discovered in unexplored rain forest areas and microhabitats.
Global species estimates range from 2 million to 100 million species. Ten million is probably nearer the mark. Only 1.4 million species have been named. Of these, approximately 250,000 are plants and 750,000 are insects. New species are continually being discovered every year. The number of species present in little-known ecosystems such as the soil beneath our feet and the deep sea can only be guessed at. It has been estimated that the deep sea floor may contain as many as a million undescribed new species. To put it simply, we really have absolutely no idea how many species there are!
Losses of Biodiversity
Extinction is a fact of life. Species have been evolving and dying out ever since the origin of life. One only has to look at the fossil record to appreciate this. (It has been estimated that surviving species constitute about 1% of the species that have ever lived.)
However, species are now becoming extinct at an alarming rate, almost entirely as a direct result of human activities. Previous mass extinctions evident in the geological record are thought to have been brought about mainly by massive climatic or environmental shifts. Mass extinctions as a direct consequence of the activities of a single species are unprecedented in geological history.
The loss of species in tropical ecosystems such as the rain forests, is extremely well-publicised and of great concern. However, equally worrying is the loss of habitat and species closer to home in Britain. This is arguably on a comparable scale, given the much smaller area involved.
Predictions and estimates of future species losses abound. One such estimate calculates that a quarter of all species on earth are likely to be extinct, or on the way to extinction within 30 years. Another predicts that within 100 years, three quarters of all species will either be extinct, or in populations so small that they can be described as "the living dead".
It must be emphasised that these are only predictions. Most predictions are based on computer models and as such, need to be taken with a very generous pinch of salt. For a start, we really have no idea how many species there are on which to base our initial premise. There are also so many variables involved that it is almost impossible to predict what will happen with any degree of accuracy. Some species actually benefit from human activities, while many others are adversely affected. Nevertheless, it is indisputable that if the human population continues to soar, then the ever increasing competition with wildlife for space and resources will ensure that habitats and their constituent species will lose out.
It is difficult to appreciate the scale of human population increases over the last two centuries. Despite the horrendous combined mortality rates of two World Wars, Hitler, Stalin, major flu pandemics and Aids, there has been no dampening effect on rising population levels. In 1950, the world population was 2.4 billion. Just over 50 years later, the world population has almost tripled, reaching 6.5 billion.
In the UK alone, the population increases by the equivalent of a new city every year. Corresponding demands for a higher standard of living for all, further exacerbates the problem. It has been estimated that if everyone in the world lived at the UK standard of living (and why should people elsewhere be denied this right) then we would either need another three worlds to supply the necessary resources or alternatively, would need to reduce the world population to 2 billion.
The only possible conclusion is that unless human populations are substantially reduced, it is inevitable that biodiversity will suffer further major losses.
Some species are more vulnerable to extinction than others. These include:
- Species at the top of food chains, such as large carnivores.
Large carnivores usually require fairly extensive territories in order to provide them with sufficient prey. As human populations increasingly encroach on wild areas and as habitats shrink in extent, the number of carnivores which can be accommodated in the area also decreases.
These animals may also pose a threat to people, as populations expand into wilder areas inhabited by large carnivores. Protective measures, including elimination of offending animals in the area, further reduces numbers. - Endemic local species (species found only in one geographical area) with a very limited distribution.
These are very vulnerable to local habitat disturbance or human development. - Species with chronically small populations.
If populations become too small, then simply finding a mate, or interbreeding, can become serious problems. - Migratory species
Species which need suitable habitats to feed and rest in widely spaced locations (which are often traditional and 'wired' into behaviour patterns) are very vulnerable to loss of these 'way stations'. - Species with exceptionally complex life cycles
If completion of a particular lifecycle requires several different elements to be in place at very specific times, then the species is vulnerable if there is disruption of any single element in the cycle. - Specialist species with very narrow requirements such as a single specific food source, e.g. a particular plant species.
Why Conserve Biodiversity?
Ecological Reasons
Individual species and ecosystems have evolved over millions of years into a complex interdependence. This can be viewed as being akin to a vast jigsaw puzzle of inter-locking pieces. If you remove enough of the key pieces on which the framework is based then the whole picture may be in danger of collapsing. We have no idea how many key 'pieces' we can afford to lose before this might happen, nor even in many cases, which are the key pieces. The ecological arguments for conserving biodiversity are therefore based on the premise that we need to preserve biodiversity in order to maintain our own life support systems.
Two linked issues which are currently of great ecological concern include world-wide deforestation and global climate change.
Forests not only harbour untold numbers of different species, but also play a critical role in regulating climate. The destruction of forest, particularly by burning, results in great increases in the amount of carbon in the atmosphere. This happens for two reasons. Firstly, there is a great reduction in the amount of carbon dioxide taken in by plants for photosynthesis and secondly, burning releases huge quantities of carbon dioxide into the atmosphere. (The 1997 fires in Indonesia’s rain forests are said to have added as much carbon to the atmosphere as all the coal, oil and gasoline burned that year in western Europe.) This is significant because carbon dioxide is one of the main greenhouse gases implicated in the current global warming trend.
Average global temperatures have been showing a steadily increasing trend. Snow and ice cover have decreased, deep ocean temperatures have increased and global sea levels have risen by 100 - 200 mm over the last century. If current trends continue, scientists predict that the earth could be on average 1oC warmer by 2025 and 3oC warmer by 2100. These changes, while small, could have drastic effects. As an example, average temperatures in the last Ice Age were only 5oC colder than current temperatures.
Rising sea levels which could drown many of our major cities, extreme weather conditions resulting in drought, flooding and hurricanes, together with changes in the distribution of disease-bearing organisms are all predicted effects of climate change.
Forests also affect rainfall patterns through transpiration losses and protect the watershed of vast areas. Deforestation therefore results in local changes in the amount and distribution of rainfall. It often also results in erosion and loss of soil and often to flooding. Devastating flooding in many regions of China over the past few years has been largely attributed to deforestation.
These are only some of the ecological effects of deforestation. The effects described translate directly into economic effects on human populations.
Economic Reasons
Environmental disasters such as floods, forest fires and hurricanes indirectly or directly caused by human activities, all have dire economic consequences for the regions afflicted. Clean-up bills can run into the billions, not to mention the toll of human misery involved. Susceptible regions are often also in the less-developed and poorer nations to begin with. Erosion and desertification, often as a result of deforestation, reduce the ability of people to grow crops and to feed themselves. This leads to economic dependence on other nations.
Non-sustainable extraction of resources (e.g. hardwood timber) will eventually lead to the collapse of the industry involved, with all the attendant economic losses. It should be noted that even if 'sustainable' methods are used, for example when harvested forest areas are replanted, these areas are in no way an ecological substitute for the established habitats which they have replaced.
Large-scale habitat and biodiversity losses mean that species with potentially great economic importance may become extinct before they are even discovered. The vast, largely untapped resource of medicines and useful chemicals contained in wild species may disappear forever. The wealth of species contained in tropical rain forests may harbour untold numbers of chemically or medically useful species. Many marine species defend themselves chemically and this also represents a rich potential source of new economically important medicines. Additionally, the wild relatives of our cultivated crop plants provide an invaluable reservoir of genetic material to aid in the production of new varieties of crops. If all these are lost, then our crop plants also become more vulnerable to extinction.
There is an ecological caveat here of course. Whenever a wild species is proved to be economically or socially useful, this automatically translates into further loss of natural habitat. This arises either through large-scale cultivation of the species concerned or its industrial production/ harvesting. Both require space, inevitably provided at the expense of natural habitats.
Perhaps the rain forests and the seas should be allowed to keep their secrets.
Ethical Reasons
Do we have the right to decide which species should survive and which should die out?
Do we have the right to cause a mass extinction?
Most people would instinctively answer 'No!'. However, we have to realise that most biodiversity losses are now arising as a result of natural competition between humans and all other species for limited space and resources.
If we want the luxury of ethics, we need to reduce our populations.
Aesthetic Reasons
Most people would agree that areas of vegetation, with all their attendant life forms, are inherently more attractive than burnt, scarred landscapes, or acres of concrete and buildings. Who wouldn't prefer to see butterflies dancing above coloured flowers, rather than an industrial complex belching smoke?
Human well-being is inextricably linked to the natural world. In the western world, huge numbers of people confined to large urban areas derive great pleasure from visiting the countryside. The ability to do so is regarded not so much as a need, but as a right. National governments must therefore juggle the conflicting requirements for more housing, industry and higher standards of living with demands for countryside for recreational purposes.
How do we Conserve Biodiversity?
There are two main ways to conserve biodiversity. These are termed ex situ (i.e. out of the natural habitat) and in situ (within the natural habitat)
Ex Situ Conservation - out of the natural habitat
(Species-based)
- Zoos - These may involve captive breeding programmes,
- Aquaria - research, public information and education
- Plant Collections - breeding programmes and seed storage
In the past, zoos were mainly display facilities for the purpose of public enjoyment and education. As large numbers of the species traditionally on display have become rarer in the wild, many zoos have taken on the additional role of building up numbers through captive breeding programmes.
Although comparatively far more invertebrates than vertebrates face extinction, most captive breeding programmes in zoos focus on vertebrates. Threats to vertebrate extinction tend to be well publicised (e.g. Dormouse, Panda). People find it easier to relate to and have sympathy with animals which are more similar to ourselves, particularly if they are cute and cuddly (at least in appearance, if not in fact!). Not many visitors to zoos are likely to get excited over the prospect of the zoo 'saving' a tiny beetle, which they can barely see, let alone spiders or other invertebrates which often invite horror rather than wonder. Vertebrates therefore serve as a focus for public interest. This can help to generate financial support for conservation and extend public education to other issues. This is a very important consideration, as conservation costs money and needs to be funded from somewhere.
The focus on vertebrates is not solely pragmatic. Many of the most threatened vertebrates are large top carnivores, which the world stands to lose in disproportionate numbers. Such species require extensive ranges to provide sufficient prey to sustain them. In many cases, whole habitats for these predators have all but disappeared. Some biased expenditure on their survival may therefore be justified.
Several species are now solely represented by animals in captivity. Captive breeding programmes are in place for numerous species. At least 18 species have been reintroduced into the wild following such programs. In many cases the species was actually extinct in the wild at the time of reintroduction (Arabian Oryx, Pere David Deer, American Bison). In some cases, all remaining individuals of a species, whose numbers are too low for survival in the wild, have been captured and the species has then been reintroduced after captive breeding (California Condor).
The role of zoos in conservation is limited both by space and by expense. At population sizes of roughly 100-150 individuals per species, it has been estimated that world zoos could sustain roughly 900 species. Populations of this size are just large enough to avoid inbreeding effects. However, zoos are now shifting their emphasis from long-term holding of species, to returning animals to the wild after only a few generations. This frees up space for the conservation of other species.
Genetic management of captive populations via stud records is essential to ensure genetic diversity is preserved as far as possible. There are now a variety of international computerised stud record systems which catalogue genealogical data on individual animals in zoos around the world. Mating can therefore be arranged by computer, to ensure that genetic diversity is preserved and in-breeding minimised (always assuming the animals involved are prepared to co-operate).
Research has led to great advances in technologies for captive breeding. This includes techniques such as artificial insemination, embryo transfer and long-term cryogenic (frozen) storage of embryos. These techniques are all valuable because they allow new genetic lines to be introduced without having to transport the adults to new locations. Therefore the animals are not even required to co-operate any longer. However, further research is vital. The success of zoos in maintaining populations of endangered species is limited. Only 26 of 274 species of rare mammals in captivity are maintaining self-sustaining populations.
Reintroduction of species to the wild poses several different problems.
- Diseases
The introduction of new diseases to the habitat, which can decimate existing wild populations. Alternatively, the loss of resistance to local diseases in captive-bred populations. - Behaviour
Behaviour of captive-bred species is also a problem. Some behaviour is genetically determined and innate, but much has to be learned from other adults of the species, or by experience. Captive-bred populations lack the in situ learning of their wild relatives and are therefore at a huge disadvantage in the wild. In one case of reintroduction, a number of monkeys starved because they had no concept of having to search for food to eat - it had always been supplied to them in captivity. In the next attempt, the captive monkeys were taught that they had to look for food, by hiding it in their cages, rather than just supplying it. - Genetic Races
Reintroduced populations may be of an entirely different genetic make-up to original populations. This may mean that there are significant differences in reproduction habits and timing, as well as differences in general ecology. Reintroduction of individuals of a species into an area where the species has previously become extinct, is in many cases just like introducing a foreigner. The Large Copper Butterfly is a good example of this. Although extinct in Britain, it persists in continental Europe. There have been over a dozen attempts to re-establish it in Britain over the last century, but none have been successful. This is probably due to the differing ecology of the introduced races. Replacement of extinct populations by reintroduction from other areas may not therefore be an option. - Habitat
The habitat must be there for reintroduction to take place. In many cases, so much habitat has been destroyed, that areas must first be restored to allow captive populations to be reintroduced. Suitable existing habitats will also (unless the species is extinct in the wild) usually already contain wild members of the species. In this case, it is likely that within the habitat, there are already as many individuals as the habitat can support. The introduction of new individuals will only lead to stress and tension as individuals fight for limited territory and resources such as food. In this case, nothing positive has been accomplished by reintroduction, it has merely increased the stress on the species. It may even in some cases result in a decrease in numbers. In contrast, the provision of additional restored habitat nearby can allow wild populations to expand into it without the need for reintroduction.
The role of aquaria has largely been as display and educational facilities. However, they are assuming new importance in captive breeding programmes. Growing threats to freshwater species in particular, are leading to the development of ex situ breeding programmes. The World Conservation Union (IUCN) is currently developing captive breeding programmes for endangered fish. Initially this will cover those from Lake Victoria in Africa, the desert fishes of N. America and Appalachian stream fishes. Natural habitats will be restored as part of the programme.
Marine, as well as freshwater species are also the subject of captive breeding programmes. For example, The National Marine Aquarium, in South West England, is playing an important role in the conservation of sea horse species through their captive breeding programme.
PLANT COLLECTIONS
Populations of plant species are much easier than animals to maintain artificially. They need less care and their requirements for particular habitat conditions can be provided more readily. It is also much easier to breed and propagate plant species in captivity.
There are roughly 1,500 botanic gardens world-wide, holding 35,000 plant species (more than 15% of the world’s flora). The Royal Botanic Gardens of England (Kew Gardens) contains an estimated 25,000 species. IUCN classifies 2,700 of these as rare, threatened or endangered. Many botanic gardens house collections of particular taxa which are of major conservation value. There is however, a general geographic imbalance. Only 230 of the world’s 1,500 gardens are in the tropics. Considering the greater species richness of the tropics, this is an imbalance that needs to be addressed.
A more serious problem with ex situ collections involves gaps in coverage of important species, particularly those of significant value in tropical countries. One of the most serious gaps is in the area of crops of regional importance, which are not widely traded on world markets. These often have recalcitrant seeds (unsuited to long-term storage) and are poorly represented in botanic collections. Wild crop relatives are also under-represented. These are a potential source of genes conferring resistance to diseases, pests and parasites and as such are a vital gene bank for commercial crops.
Plant genetic diversity can also be preserved ex situ through the use of seed banks. Seeds are small but tough and have evolved to survive all manner of adverse conditions and a host of attackers. Seeds can be divided into two main types, orthodox and recalcitrant. Orthodox seeds can be dried and stored at temperatures of -20oC. Almost all species in a temperate flora can be stored in this way. Surprisingly, many tropical seeds are also orthodox. Recalcitrant seeds, in contrast, die when dried and frozen in this manner. Acorns of oaks are recalcitrant and it is believed that so are the seeds of most tropical rain forest trees.
The result of storing seeds under frozen conditions is to slow down the rate at which they lose their ability to germinate. Seeds of crop plants such as maize and barley could probably survive thousands of years in such conditions, but for most plants, centuries is probably the norm. This makes seed banking an attractive conservation option, particularly when all others have failed. It offers an insurance technique for other methods of conservation.
All of the ex situ conservation methods discussed have their role to play in modern conservation. Generally, they are more expensive to maintain and should be regarded as complementary to in situ conservation methods. For example they may be the only option where in situ conservation is no longer possible.
In Situ Conservation - within the natural habitat
(Habitat or species-based)
Protected sites, or Reserves
In situ conservation maintains not only the genetic diversity of species, but also the evolutionary adaptations that enable them to adapt continually to shifting environmental conditions, such as changes in pest populations or climate. In situ conservation also ensures that along with target species, a host of other interlinked species are also preserved as a by-product. It is generally cheaper than ex situ methods (although not cheap). It may often be the only conservation option, for example for species with recalcitrant seeds.
In situ conservation measures involve designating specific areas as protected sites. Protection may be offered at various levels, from complete protection and restriction of access, through various levels of permitted human use. In practice, complete protection is rarely necessary or advisable in a terrestrial context. Human beings have been a major part of the landscape for many thousands of years. Over the course of that time, human cultures have emerged and adapted to the local environment, discovering, using and altering biotic resources. Many areas that now appear ‘natural’ bear the hallmarks of millennia of human influence. Other species have evolved along with that influence and in many cases require the disturbance provided by humans to provide the necessary conditions for their survival. In other words, it is rarely advisable to relegate the countryside to the status of a museum piece.
This applies particularly in the less economically developed areas of the world, where in many cases, the livelihood of the local people depends on using the natural resources available to them. Prohibiting the use of such resources in protected areas means that expensive enforcement measures usually have to be put in place. It is far better to involve local people in conservation and to find creative ways for them to make a sustainable living while still protecting valuable habitats or species.
The biosphere reserve concept has been developed through the Man and Biosphere (MAB) Programme of the United Nations Educational, Scientific and Cultural Organisation (UNESCO). Biosphere reserves are an attempt to reconcile the problems of conserving biodiversity and biological resources, with sustainable use of natural resources for people. They form an international network of sites, nominated by national governments, but designated by UNESCO. The first reserves were nominated as long ago as 1976. By 2001, a network of 393 reserves in 94 countries had been developed.
Marine conservation areas lag behind terrestrial ones. Protected areas have existed on land for over a century, but there is no tradition of managing marine areas for conservation. The only current statutory marine reserve in England is Lundy Island. This harbours a huge variety of marine life due to the diversity of underwater habitats present there.
Marine reserves may be vital tools in preserving species-rich areas such as tropical coral reefs, which are being devastated by non-sustainable fishing methods in many areas. The rationale of such reserves is not to lock away fish from fishermen, but rather to create refuges inside which populations can build up and spill over to repopulate adjacent areas.
Marine Reserves need to be carefully designed to take into account, movement patterns, dispersal rates and population dynamics of particular target species. For example, it would be pointless having a reserve where the resident species regularly travelled to non-protected areas. It would also be pointless protecting the habitat of an adult, but neglecting the geographically different breeding grounds and habitats of juveniles, or vice versa. Such factors should also be taken into consideration in the design of terrestrial reserves.
Management of Nature Reserves
Nature reserves are usually designated to protect a particular species, assemblage of species, or specific habitats. As such they can rarely be left in isolation to manage themselves. Management is necessary in order to prevent natural processes such as succession from taking place. Such resulting changes in habitat may mean the loss of particular species for which the reserve was originally designated.
Succession is a natural process which will tend to replace particular species with different ones. This is often as a result of ecological change induced by the organisms themselves. In former times, while an area of a particular habitat might be lost through succession (such as a wetland drying out and eventually becoming a woodland), there would always be other wetland habitats at an earlier stage of the succession process elsewhere. These would act as species reservoirs. With the drastic loss of area of natural habitat occurring world-wide, this is often no longer the case. The decision therefore has to be made to halt succession at a particular stage in order to preserve the species associated with it. Examples of this include wild flower meadows, wetlands and heathlands.
RESTORATION
Restoration attempts to bring land modified by human use back to its original state. Because determining the original natural state is often difficult and because ecosystems continually change, this is rarely a realistic goal. Changes may also in some cases be irreversible, so that restoration to an original condition is not an option. For these reasons, restoration is often limited to the approximate recreation of habitat.
Restoration does not necessarily require intervention. Left to natural processes, many ecosystems will return to their original condition provided populations of the original species still exist nearby. This may however be a lengthy process. In Brazil’s caatinga forest, natural recovery of slash and burn agricultural sites takes more than a century. Sites cleared by bulldozer may take a thousand or more years to recover. Intervention may be used to speed up the process. It becomes vital where an ecosystem will never recover naturally, either because it has been physically transformed, or because species cannot migrate to repopulate the area. Restoration may rely heavily upon species maintained by ex situ methods and is an example of the complementary nature of in situ and ex situ techniques.
RECOVERY OF THREATENED SPECIES
The recovery of threatened species generally hinges on providing suitable habitat and conditions in which they can thrive. Most biodiversity losses can be directly attributed to habitat loss, so provision of habitat is often the key requirement for recovery of a species. The dormouse (Muscardinus avellanarius) is a good example of this.
Dormice are the subject of a species recovery program sponsored by English Nature. They thrive in deciduous woodland and overgrown hedgerows. They are arboreal and require networks of interlinking low branches to provide aerial highways to food sources (e.g. hazel nuts and honeysuckle). In former times, the practice of coppicing woodland (cutting trees near to ground level and then allowing them to regenerate numerous shoots) provided ideal conditions for dormice. However, coppicing is little practised these days, with the result that large areas of former habitat have become unsuitable for dormice. Recovery therefore hinges on providing suitable areas for the species.
Dormice also suffer from competition with an introduced species, the grey squirrel. Both species compete for the food resource of hazel nuts.
INTRODUCED SPECIES
The vast majority of exotic introduced species die out because they are unsuited to local conditions. A few however, appear to be superbly adapted to particular local conditions and will tend to out-compete native species.
Regulatory policies are necessary to curb the introduction of exotic species and genetic resources, as the consequences can be disastrous. Introduced species can wipe out innumerable other local species. Between 1967 and 1972, an African cichlid fish introduced into a lake in Panama wiped out 6 of the 8 previously common fish species, drastically reduced populations of a seventh and affected aquatic invertebrates, algae and fish-eating birds up and down the food chain.
In Britain, particularly in the west, rhododendron has taken over large areas, virtually eliminating native plants and their associated faunas. This one species alone has decimated tens of thousands of acres. Grey squirrels introduced from America have also all but replaced native red squirrel populations.
Even introducing the same species can present hazards through the mixing of genetic stocks. Fish populations can be contaminated by interbreeding with introduced varieties. The genetic integrity of native British Red Deer is now also threatened through hybridisation with introduced Sika Deer. Pure Red Deer may in the end be confined to isolated islands in Scotland.
GENETIC MODIFICATION
Humans now have the technology to alter life on earth in a totally unique way. Genetic engineering can involve the transfer of genetic material between widely separated taxonomic groups. e.g. Genes from a fish have been introduced into tomatoes. Entirely new species can intentionally or unintentionally be produced. There is no guarantee that all the results will be beneficial or can even be controlled.
LEGAL PROTECTION
Nature reserves need to be properly protected from the adverse results of human activity. This might be indirect, as in for example, habitat degradation through pollution brought about by activities elsewhere. Alternatively, it may involve direct damage, as in unauthorized extraction of resources from the reserve. Such protection requires the presence of a legal framework which can be effectively enforced.
Conservation at the National Level
National governments are vital to the preservation of biodiversity through the passing of laws requiring protection of species and habitats. If national laws do not protect species, then there is little hope of preserving them. However, it is not enough just to have laws, there must also be the will and the resources to enforce them. Even in economically developed nations, the necessary resources to properly enforce laws are not always made available. In under-developed nations, even the most basic resources for enforcement may be lacking. In addition, national laws may not in the end translate into local action, in which case they do not accomplish much. In democratic nations, national laws are also driven to a large extent by public opinion. They may in some cases be drafted more as a response to emotion than by actual scientific need.
Several international conventions exist for the preservation of biodiversity. These include such conventions as the Ramsar Convention (1976) which provides for the conservation of internationally important wetlands and the Bern Convention (1979) which requires the protection of endangered and vulnerable species of flora and fauna in Europe and their habitats. There are many others. Signatory nations to these conventions must ratify national laws to ensure compliance with the conventions.
In Britain, the main piece of legislation covering conservation is the Wildlife and Countryside Act 1981 and 1985, which implements preceding EU conventions. It protects both species and sites of UK importance. Enforcement of conservation directives is the responsibility of the Environment Agency, a government organisation. English Nature, a government funded watchdog, is also responsible for the promotion of the conservation of England’s wildlife.
In addition to the enforcement of laws, the Environment Agency is also responsible for data collection and monitoring. Environmental monitoring and biodiversity surveys are important because they provide information on the condition of ecosystems and the changes that are taking place within them. They therefore provide the scientific information on which to base environmental policy decisions. Similarly, assessments of the environmental impact of large development projects are vital before relevant authorities can either grant permission to proceed, or require that changes be made to development designs.
International Conservation
Species and ecosystems are seldom neatly confined within national boundaries. Many species roam across countless national borders and the oceans are owned by none. Trade in endangered species (or parts thereof) is international and pollution produced on one side of the world may wind up affecting regions on the other side of the globe. Biodiversity conservation is thus an international problem requiring international solutions.
The role of international conservation organisations is a vital one, particularly in terms of brokering international agreements between governments concerned with protecting their national interests. The most far-reaching agreement on biodiversity in recent years is the Convention on Biodiversity, signed by 156 nations at the United Nations Conference on Environment and Development ( the Earth Summit ) in Rio in 1992. Many others have signed since, and as they ratify the convention, governments accept responsibility for safeguarding biodiversity in their nations. Many international conservation organisations including WRI ( World Resources Institute ) and IUCN ( The World Conservation Union ) contributed to the formulation of the documents signed at the convention.
The UK was one of the first countries to follow up its commitment under the Convention on Biodiversity.
Biodiversity: The UK Action Plan was published in January 1994. A UK Biodiversity Steering Group was appointed , which published a report entitled Meeting the Rio Challenge in 1995. The report contains action plans for over 100 endangered species and 14 key habitats, together with a commitment to produce further plans. The Steering Group proposed the use of a standard methodology for the production of local biodiversity action plans. These would be based upon the priorities of the UK plan, but would be supplemented by local priorities.
Action Plans seek to apply principles of business planning to a strategic view of the environment. They identify objectives, set quantified targets and define the actions needed to reach those targets. The Nature of Devon - A Biodiversity Action Plan is Devon’s response to this national biodiversity planning process. This regional process is going on throughout England. The sum of all the regional Biodiversity Action Plans should add up to the full UK Biodiversity Action Plan.
International conservation organisations play an important role in the wide publicising of environmental information. IUCN was responsible for the idea of compiling lists of threatened species as a means of drawing attention to the plight of species faced with extinction. These lists became known as Red Data Books ( RDBs ). In these, species are placed into one of several categories which range from ‘extinct’ to ‘vulnerable’ or ‘rare’, depending on the degree of threat to their existence. The first internationally applicable RDB was published in 1996. The ‘red’ stands for ‘danger’ and the concept has since been adopted by many different countries, including Britain. RDBs point the way for government agencies charged with environmental protection, as well as for non-governmental organisations ( NGOs ) concerned about maintaining diversity.
Organisations such as WWF, founded in 1961 by Sir Peter Scott, the eminent naturalist, are highly effective in publicising the plight of endangered species world-wide. They also play a large role in raising charitable funds towards projects concerned with saving wildlife in various areas of the globe. Many such conservation organisations pay for the basic resources needed by under-developed countries to enforce their laws. This can be as basic as providing a means of transport and salaries for enforcement officers. However, how effective these campaigns and projects are in the long run remains to be seen. Loss of habitat is still the most pressing problem.
In some areas, biodiversity is seriously threatened as a result of trade in endangered species. The international trade in wildlife is estimated to be worth £12 billion a year. Up to a quarter of that trade is almost certainly illegal. The main piece of legislation limiting trade in endangered species is CITES (the Convention on International Trade in Endangered Species). This is a UN convention which came into effect in 1975. CITES prohibits commercial trade in endangered species of plants and animals. Legitimate international trade in species which are not now threatened, but which may become so if trade is not controlled, is allowed via a permit system. Responsibility for implementing it lies with signatory nations.
Many of the problems involved in protecting habitats and species arise because local people either need to use the resources available in sensitive habitats to provide the necessities for subsistence or survival, or traditionally have always done so. UNESCO (United Nations Educational, Scientific and Cultural Organisation), through its 'Man and the Biosphere' programme, has set up a number of Internationally recognised biosphere reserves in an attempt to address this problem.
Overview
The world has a vast range of different species which are all inextricably linked. The eminent naturalist and television presenter, Sir David Attenborough, summed this up neatly when he said "The inter-dependence of species evolved over millions of years and underpins the complex diversity of life which exists on this planet."
We can only guess at many of the interactions taking place within habitats. While we have come a long way in our knowledge of the natural world, we need to recognise that we are still fundamentally ignorant. With recognition of this ignorance comes the understanding that we need to preserve whole habitats intact, so that the complexity of interactions remains, whether we understand them or not.
The fate of the entire planet is now dependent upon a single species - humans. This is unprecedented in the Earth’s 4.7 billion year history. Ultimately, conservation of biodiversity will hinge upon the control of human populations. Continually expanding human numbers have led to an escalating competition with wildlife for the space required to house everyone, as well as to produce enough food to feed them. Increasing standards of living also require that further natural areas and resources are given over to sustaining western lifestyles and associated demands.
We are interfering with biodiversity on a great many levels, from the molecular (genetic modification), all the way through habitats and possibly global climate change as well. However, the many predictions made about species and habitats losses need to be carefully examined in each case and not just taken at face value. Many are based on computer simulations and emotions can get in the way of clear practical thinking.
Anyone concerned about conservation needs to question whether the innumerable strategies and policies in place are actually being delivered. International conventions and national laws are in the end only ideas on pieces of paper. These must be translated into concrete action in local situations for anything to be truly accomplished.
On the plus side, it is possible to restore some habitats which have been lost or degraded. This is not to imply that it is permissible to destroy habitats in the first place. This causes the local extinction of all the species in the habitat and it can take hundreds of years for complex ecosystems to become re-established. The species which have recolonised the restored habitat will also not necessarily be of the same genetic make-up as the original inhabitants.
However, restoration does mean that action can be taken to repair damage. The natural world given half a chance is amazingly resilient. All it needs is space and time.
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