Biodiversity

There are many different criteria taken into account when assessing nature or if certain habitatsshould be considered worthy of protection. These include ethical, aesthetic, or economic factors. Alongside traditional conservation criteria such as the rarity and threat of species or habitats, biological diversity (biodiversity) has emerged as a central assessment criterion in nature conservation, especially in relation to Natura 2000, particularly since the "Convention on Biodiversity" (CBD) in Rio in 1992. Biodiversity is measured and mapped across three levels (Nentwig et al. 2017, Baur 2021):

• Genetic diversity within a species,
• Species diversity, mainly measured by the number of species present in a community or ecosystem, and
• The Diversity among different communities or ecosystems across entire landscapes

The most critical and effective aspect of nature conservation is undoubtedly biological diversity at the species level, which primarily reflects the number of species within a habitat. Although not all habitats of high nature value are species-rich, species richness is likely the most significant scientific argument for nature conservation: A high number of species within an ecosystem boosts productivity (see graphs on the right) and increases the system’s resilience to environmental stress (Baur, 2021).

Changes in species numbers provide valuable insights into the overall state of biodiversity, or into the state of specific ecosystems, nature reserves, or other areas. To assess these changes, it is necessary to continuously monitor species numbers or the abundance of certain species over extended periods, using scientifically sound methods.

Sources

Nentwig, W., Bacher S., Brandl, R. (2017): Ecology – A Compact Guide, 4th ed., Springer Spektrum, Heidelberg.
Baur, B. (2021): Conservation Biology, UTB-Band 5416, Haupt-Verlag, Bern.