- Diversity is vital
- Beauty in jeopardy
- Ecological services
- What destroys biodiversity?
- The human manipulator
- Dialogue for Sustainability
- Changing Course
Beauty in Jeopardy
Nature has countless ways of catching the eye – through striking colours and patterns, intricate and fascinating life cycles and intriguing survival strategies. In the wild or in untouched waters we are often overcome by a sense of awe when observing creatures such as bright coral fish, agile predators and frail flowers clinging to the side of a cliff. But cultured landscapes such as fish ponds, parks and gardens and the forests and pasture landscapes of the Alps also bring us a sense of peace or joy. Our sense of aesthetics and spirituality depends on the plants, animals and landscapes that we and our ancestors have lived among and from.
The number of species on this planet is yet another wonder and our knowledge about them is incomplete. About 1.8 million species have been described to date, but biologists estimate that our planet is home to anywhere between three and 100 million species.
However, the treasure we have scarcely fathomed is already dwindling dramatically.
Dramatic changes
Scientists have found that, over the past 30 years alone, the population sizes and habitats of all known species have shrunk by 40% on average; continental aquatic species have lost 50% of their populations, and marine and terrestrial species 30%. It is estimated that 26,000 species become extinct each year – that is one every 20 minutes! Many of these species took hundreds of thousands of years to evolve and we often only know little or nothing at all about them.
It is part of the natural course of evolution for some species to die out, in response to changing environmental conditions or competition from more successful rivals. However, the current rate of species extinctions is estimated at some 100-1,000 times higher than the “background” rate, the norm over hundreds of millions of years of geological time. Thus it is not surprising that newly-discovered plants or animals are immediately listed as being at risk of extinction from the moment they are described.
Our planet is now experiencing the sixth major extinction event, the last of which took place 65 million years ago and included the disappearance of the dinosaurs. Unlike the previous five, however, this event is entirely due to the activities of one single species; Homo sapiens. For millions of people, species loss on this scale is unacceptable in its own terms. The concept of stewardship of the Earth runs deep in many societies – and naturally so, since our survival and quality of life is intricately linked with the quality of our environment.
Biodiversity is the necessary condition for continuous evolution and we should not simply evaluate it in terms of its usefulness to humans – but as a part of a whole and unique system. We need to reintegrate this understanding in our lives and to assume the responsibility we have to care for our planet.
Next chapter: Ecological Services
Trends in abundance and distribution of selected species
The Living Planet Index: trends in populations of terrestrial, freshwater and marine species worldwide.
There is a continuing decline in the population size and geographical range of the majority of species across different groups of animals. This holds true for amphibians globally, African mammals, birds in agricultural lands, British butterflies, corals in the Caribbean and Indopacific region, and commonly caught fish species.
The Living Planet Index, which monitors trends of some 3,000 populations of wild species, serves as an indicator of the changes that occur over time.
Trends in genetic diversity of domesticated animals, cultivated plants, and fish species of major socio-economic importance also provide an alarming picture. About 7,000 plant species have been cultivated and collected for food by humans since agriculture began about 12,000 years ago. Additionally, agriculture has fostered some 6,500 recognised domesticated animal breeds. Today, however, one third of the domesticated animal breeds are estimated to be threatened by extinction with only about 15 plant species and 8 animal species supplying 90% of our food. Since we now depend on a small number of domesticated animal and plant species, genetic variation is important to maintain high yields, disease resistance and resilience to changing environmental conditions.
It has been widely reported that this genetic diversity is also being lost through the disappearance of locally-adapted varieties, and the global marketing of standard seed-types.