Biodiversity is, simply, the variety of life on earth. The term 'biodiversity' was coined by the American zoologist Edward O. Wilson and is an abbreviation of 'biological diversity'. This diversity encompasses the variation between and within ecosystems, ecological communities and populations, as well as between and within individual species.

Article two of the Convention on Biological Diversity defines biodiversity as:

'The variability among living organisms from all sources including, amongst others, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.'

'Biodiversity' is essentially another word for nature but places a particular emphasis on the interconnectedness and interdependence of all living things. The variation in scale at which nature can be described, at which natural processes and ecological change occur - from the global, through ecosystems, communities, populations to between individuals - is a key element of the concept of biodiversity.

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The importance of Biodiversity

The world is losing species and habitats at an accelerated rate as a result of human activity. Evolution cannot keep up with the rate of loss and change and does not have time to compensate. There are many reasons why conservation of biodiversity might be considered important:

• Species that have evolved over thousands or millions of years may be lost very quickly and cannot be recreated. Current estimates suggest that it will take millions of years of evolution before the total number of species on earth recovers from the losses we are now inflicting. There is considerable uncertainty about the values, including economic values, which future generations may attach to biodiversity.

• Biological organisms do not live in isolation from each other, rather they are interdependent. The loss of one may affect the capacity of many others to survive.

• Conservation of biodiversity can be viewed as insurance. Our future practical needs are unpredictable and our understanding of ecosystems is insufficient to be certain of the impact of removing any component. The less diverse biological systems are, the less likely they are to be able to adapt to and survive change.

• Loss of biodiversity is therefore another de-stabilising factor, in a world already changing unpredictably in response to almost certain climate change, continuing ozone depletion, and global pollution of many kinds. It thereby increases the potential for change and our uncertainty about what that change might bring.

• Natural processes help to protect our planet, the human environment and provide 'environmental services'. For example wetlands, comprising a complex of soils, microbes and plants, act as natural filters for surface waters and also provide natural flood prevention and control systems. Woods and hedges act as wind breaks. Upland vegetation prevents soil erosion.

• Biological resources may be renewable but, in human terms, may take a great deal of time to recover.

• Some species have direct commercial value, such as through forestry. Others have potential value in the future development of medicines, fibres or through 'eco-tourism'.

• In maintaining the productivity of our crops we depend upon a reservoir of wild relatives and a pool of genetic material that we can go back to, in order to reinforce our selection.

The moral and aesthetic reasons for conserving biodiversity are less tangible but of considerable importance. The culture of a nation is closely allied to its landscapes and wildlife. Poets, painters, writers and composers have been inspired by the nature around them.

The UK Biodiversity Action Plan states that:

'Our planet's essential goods and services depend upon the variety and variability of genes, species, populations and ecosystems. Biological resources feed and clothe us and provide medicines and spiritual nourishment. The natural ecosystems of forests, savannahs, pastures and rangelands, tundras, rivers, lakes and seas contain most of the Earth's biodiversity. Farmers' fields and gardens are also of great importance... The current decline in biodiversity is largely the result of human activity and represents a serious threat to human development.'

If we wish to hand over to the next generation an environment no less rich than the one we have ourselves inherited, urgent action to conserve biodiversity is essential.

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Threatened Biodiversity - The Need for Action

Biodiversity is declining both globally and locally. It has been estimated that somewhere in the region of 100 species per day are going extinct globally. In the UK more than 100 species were lost during the twentieth century. These included 7% of dragonflies, 5% of butterflies and more than 2% of fish and mammals.

Losses in the UK have been particularly rapid and generally accelerating, over the last fifty years. During that period 97 of hay meadows have been lost. Between 1984 and 1993, almost 100,000 miles of English hedges were grubbed out, reducing the total length from 302,000 miles to 204,000 miles. The loss, fragmentation and isolation of wildlife habitats further endangers the species that depend upon them, as the remnants may be too small to support a viable population, too widely scattered for movement between sites to be possible, or surrounded by hostile habitat, making movement impossible. Species lost to the UK in recent years include corncockle, thorow-wax and small bur-parsley. Populations of many species are declining at an alarming rate, for example numbers of breeding skylarks and song thrushes have declined by over 50% in the last 25 years while the once common cornflower and pheasant's eye have become rare.

Locally important losses have occurred too. Habitat loss in Herefordshire has followed the national trend, with an estimated 69 of species-rich grassland being lost over the last 20 years and hedgerow loss having accelerated since the 1970s. Species lost to Herefordshire in the last 25 years have included breeding corncrake and red-backed shrike. These follow losses to the county throughout the past century, which include black grouse, the marsh fritillary butterfly and the cornflower.