Botanic gardens are the zoos of the plant world. There are about 1,600 of them, containing roughly a quarter of all species of flowering plants and ferns. They are visited each year by about 150 million people worldwide and, as with zoos, public education is an important function. Some gardens incorporate herbaria, where plant specimens are dried and held to provide a permanent reference for plant diversity. Botanic gardens often also maintain seed banks. Seeds are only viable for a certain period, so drying and low-temperature storage (“cryopreservation”) is used tp prevent them germinating or rotting.
Eco-labelling of timber can exploit market mechanisms to promote conservation. The Forest Stewardship Council administers a certification scheme for timber extracted according to strict ecological principles. These aim either to leave forests largely intact or to give the species that are cut down an opportunity to regenerate. The success of such conservation strategies relies on harnessing the knowledge of local people about the plants around them.