18.3.2—Reasons to maintain biodiversity

Maintaining biodiversity protects ecological relationships and preserves options for people and other species. The reasons overlap: ecosystems, species and genes support one another, so loss at one level can reduce benefits at others.

• Ecological stability and resilience — more diverse ecosystems may contain species able to tolerate environmental change, while loss of a keystone species can disrupt many other organisms.
• Environmental services — plants, fungi, bacteria and other organisms contribute to carbon dioxide absorption, the water cycle, decomposition, nutrient cycling and food webs.
• Genetic resources and future value — wild relatives can provide alleles that help crops resist disease or other disasters, and organisms may contain medicines or useful materials that have not yet been discovered.
• Economic value — biodiversity supports medicines, ecotourism, employment, science and technology.
• Social, cultural and aesthetic value — natural environments provide recreation, inspiration and opportunities for people to connect and learn.
• Moral and ethical value — people may regard humans as responsible for reducing human-caused loss and valuing other species.

These reasons are interdependent rather than isolated: genetic and species diversity can support ecosystem resilience; functioning ecosystems provide services and resources; and those benefits affect human wellbeing and future choices. The evidence supports a general reason to maintain biodiversity, not a guarantee that every diverse ecosystem resists every disturbance.

Do not reduce conservation value to economic usefulness alone, and do not assume that an ecosystem service or future genetic resource is certain or unlimited. This card explains why biodiversity matters; conservation methods, assisted reproduction, invasive-species control and IUCN/CITES tools are separate cards.