The assessment of conservation status is not yet complete on all groups of plants, but we already have some preliminary results and key findings.
- more than 20 per cent of plants are threatened with extinction
- the most threatened habitat is tropical rain forest
- the greatest threat is habitat loss caused by human activities, such as the conversion of natural habitats for agriculture or livestock use
- gymnosperms (the group that includes conifers and cycads) are the most threatened group
- 33 per cent of plants are so poorly known that we still don't know whether or not they are threatened
Current status of plants
While 21.5 per cent of global plant species are currently threatened with extinction (IUCN Red List categories Vulnerable, Endangered and Critically Endangered), a further 10 per cent are Near Threatened. These could become threatened without conservation efforts.
The IUCN Red List calculates values of overall threat for groups of species. A value of 1 indicates that no species in that group are threatened, whereas a value of 0 indicates that all species have gone extinct.
For plants as a group, the Sampled Red List Index for Plants has a value of 0.86, meaning:
- plants are more threatened than birds
- plants are as threatened as mammals
- plants are not as threatened as amphibians.
Trends over the last 15 to 25 years show declining values for birds, mammals and amphibians, with amphibians experiencing the steepest decline.
Further assessments of plants in the future will define the trend for this group, which will depend on conservation efforts.
Which plants and why?
The results of the Sampled Red List for Plants allow us to identify for the first time which plants are most threatened and why.
Percentage of plants species threatened with extinction by group:
- bryophytes (preliminary results): 15 per cent
- gymnosperms: 36 per cent
- monocotyledons: 22 per cent
- pteridophytes: 14 per cent
- legumes:12 per cent
Most of the identified species are restricted to very small areas (smaller than Wales) and are threatened by habitat destruction.
Oceanic islands host fewer species in total, but many species found there are found nowhere else, making them more likely to be threatened, especially by the introduction of invasive species.
The region of the world with the most threatened species of plants is tropical America.
Most threatened species are found in the tropics, where plant diversity is greatest. In temperate regions species are generally more widespread and less threatened.
Importance of plants
Plants provide the foundation for most of the world's ecosystems and provide us with essential services.
Plants provide three types of services:
- Provisioning services, such as food, water, timber, medicine, soil, fibres and shelter. Traditional medicines based on plants represent primary health care for 80% of people in developing countries.
- Cultural services, such as recreation and aesthetic, spiritual and social appeal.
- Regulating services, such as climate control, water quality, erosion control and soil. Plants absorb 20 per cent of fossil fuel emissions, and forests can be more valuable as water and soil erosion regulatory systems than as timber.
Drivers of threat
Human activities account for 81 per cent of threats to plants, far outweighing natural drivers of change.
Conversion of natural habitat to agricultural land directly impacts 33 per cent of threatened species, and constitutes the single greatest threat to plants worldwide.
Human population is growing, and despite advances in technology and culture we still depend on ecosystem services. Population growth and environmental change increase the pressure on ecosystems.
Ecosystems have evolved to function with all their species acting as components in a machine. As individual species are lost from the system, the machine comes apart and may collapse, causing the loss of ecosystem services we depend on.
Safeguarding our future
More than 60 per cent of threatened species are found in tropical rainforest habitats. While plants absorb almost 20 per cent of carbon emissions from fossil fuels, clearing and burning of tropical forests accounts for 20 per cent of global carbon emissions.
Stopping forest destruction would not only reduce biodiversity loss, but also make a significant contribution towards dealing with climate change. This is an example of a win-win situation for us and for thousands of other species.
Conversely, the rapid, large-scale extinction of plant species would have a knock-effect on other groups of species including ourselves.