Biodiversity, the diversity of living things is in trouble.
How many species are threatened?
What can we do to prevent them from extinction?
The truth is, there's much we don't yet know.
We're still busy identifying which species is which and which ones are in danger.
If we don't know which ones are threatened,
how can we protect them?
This is especially the case for plants
and you cannot understate their importance.
Plants give us crops for food,
fuel, clothes, timber, animal feed, medicines.
They absorb pollution and carbon dioxide.
They capture and filter the water we drink.
They provide the very oxygen we breathe.
The loss of a plant species affects every animal,
big and small, directly or indirectly connected to it.
Take the black cinnamon tree in southeast Brazil.
The fruit is eaten by mammals and birds, which spread the seeds.
Flies feed on the nectar in the blossom,
flies are eaten by spiders and mantises,
eaten in turn, by frogs and toads, which are eaten by snakes.
If this tree is lost, then a whole ecosystem is damaged.
The black cinnamon tree was harvested for timber and essential oil
extracted from the bark to perfume our soaps and shampoos.
Slow-growing, found only on the tops of hills in the Atlantic rainforest
it's already on the verge of extinction.
The extinction risk of every species
should be cataloged in the IUCN Red List,
telling us how threatened a certain species is,
whether their populations are increasing or decreasing, and why.
But there are hundreds of thousands of plant species,
many not studied for decades, and we're a long way
from having every species assessed for the red list.
So, if the precise number threatened with extinction is unknown,
it's valuable to estimate how many and which kinds of plants are threatened,
where and why.
This is the aim of the Plants Under Pressure program.
Taking a small sample of all plant species selected at random
we can represent broad patterns of plant diversity across the world.
But to find out where each species is from,
we can't simply find it all on the internet or in a library.
The information we need is on specimens in herbaria,
preserved plant collections with very accurate records of the time and place they were taken.
The distributions can then be matched to satellite images
to see the condition of their natural habitat over time.
By measuring a species range, how isolated populations are and whether a population
is declining or fluctuating, species can be cast into a red list category.
Combining red list assessments for thousands of species around the world
allows us to calculate the overall status of plants worldwide.
This research has revealed that more than one in four plants
meet the IUCN criteria for threatened species.
That's at least 100,000 species heading for extinction worldwide,
and the figure could be even higher.
Most of the species under greatest threat are found in the tropics,
where there is the greatest diversity of plants
and on islands where unique plants have evolved.
Especially vulnerable are those species with small ranges,
which only thrive in specialised conditions.
Most species are threatened by changes to their habitat,
clearing vegetation for crops, intensive livestock farming,
growing settlements, mining, logging and fires,
accidental or deliberate.
Mass clearance of vegetation brings us closer to wild animals,
enabling viruses to co-evolve, jumping from animal to human.
It's clear that plants in all their wonderful diversity are continuing to decline.
As we assess more species and their traits,
where they're from and why they’re threatened,
our knowledge becomes more detailed,
enabling more effective actions to conserve plants
and everything that relies upon them, including us.