bat biodiversity partnership - What is biodiversity?

Biodiversity includes diversity within species (genetic variation), between species and the diversity of ecosystems. Biodiversity is essentially everywhere.

Ecosystems are a major component of biodiversity, a “dynamic complex of plant, animal and micro-organism communities and the non-living environment interacting as a functional unit”.1 Ecosystems include terrestrial, marine and aquatic ecosystems, such as rainforests, coral reefs and wetlands, as well as managed systems such as plantations and agricultural landscapes.

One important measure of biodiversity is the number of species in a given area. The 1.75 million species that have been formally identified represent only a small portion of the total species richness on Earth, with estimates ranging from 5 million to over 30 million.2 The evolution of new species and the extinction of others are natural processes but, due to human activity, the rate of species extinction has increased dramatically. It is suggested that the world now faces a rapid net loss of biodiversity.3

According to the IUCN Red List of Threatened Species4  – a global database which aims to identify and prioritise the individual species most in need of conservation – 17,291 species out of the 47,677 species on the database are threatened with extinction. Around 21% of all known mammals, 30% of amphibians, 70% of plants and 35% of invertebrates are classified as under threat.

Why is biodiversity important?

Today’s biodiversity is the product of millions of years of evolution. Biodiversity underlies all ecosystem processes and its loss can strongly reduce the provision of ecosystem services. 

Ecosystem services are defined by the Millennium Ecosystem Assessment (MEA) as “the benefits people obtain from ecosystems”. These include:

  • Provisioning services such as food, freshwater and fuel;
  • Regulating services such as pollination, water purification and climate regulation;
  • Supporting services such as soil formation, nutrient cycling and the production of atmospheric oxygen; and
  • Cultural services such as spiritual fulfilment and recreational enjoyment.5

Humans are highly dependent on the protection and maintenance of healthy ecosystems, which provide such a broad and vital range of services. However, over the past 50 years, mankind has changed these ecosystems more rapidly and extensively than in any comparable period of human history, largely to meet rapidly growing demands for food, fresh water, timber, fibre, and fuel6. More than 60 % of ecosystems are being degraded or used unsustainably.7

The most important direct causes of biodiversity loss and change in ecosystem services are habitat change, climate change, the introduction of invasive alien species, overexploitation of species and pollution8. These in turn are often caused by human activity resulting from demographic, economic, socio-political or cultural changes. 

Biodiversity, ecosystem functioning and ecosystem services

Biodiversity is both affected by global change drivers and affects ecosystem processes and services, and human well-being.9

 Source: Adapted from the Millennium Ecosystem Assessment10

Biodiversity, ecosystem functioning and ecosystem services

  1. United Nations Convention
  2. MEA: Ecosystems and Human Well-being: Current State and Trends Assessment, page 79
  3. MEA: Ecosystems and Human Well-being: Current State and Trends Assessment, pages 104–105
  4. IUCN: Red List of Threatened Species
  5. MEA: Ecosystems and Human Well-being: Biodiversity Synthesis, page V
  6. MEA: Ecosystems and Human Well-being: Biodiversity Synthesis, page 1
  7. MEA: Ecosystems and Human Well-being: Current State and Trends Assessment, page 105
  8. MEA: Ecosystems and Human Well-being: Biodiversity Synthesis, page 4
  9. MEA: Ecosystems and Human Well-being: Biodiversity Synthesis
  10. MEA: Ecosystems and Human Well-being: Biodiversity Synthesis, page 28