ENVIRONMENT: World’s botanical gardens safeguard endangered plants

Botanical gardens are a Noah’s Ark for endangered plants, collectively safeguarding four out of 10 species known to face extinction. But the otherwise reassuring number hides a serious imbalance, researchers reported in the science journal Nature Plants, last week.

Such gardens, which often double as research centres, house only a quarter of tropical flora, as opposed to 60 per cent of plants native to temperate climes.

Species diversity is far richer in the tropics, but more than 90 per cent of vegetal safe havens are in the northern hemisphere.

Plants are essential for life on earth. They play a crucial role in regulating the climate, maintaining soil fertility, and the purification of water and air. They also provide food, medicines, building materials and fuel to sustain human life. And yet more than a fifth of wild plant diversity is threatened with extinction, earlier research has shown. The biggest threat is humanity’s expanding “footprint”, already encroaching on three-quarters of all land area — 40 per cent of which has been given over to agriculture.

'OUR BEST HOPE'

“The global network of botanical gardens is our best hope for saving some of the world’s most endangered plants,” said senior author Samuel Brockington, a researcher at the University of Cambridge in England.

“If we fail to conserve our plant diversity, humanity will struggle to solve the global challenges of food and fuel security, environmental degradation, and climate change,” he added.

To find out what percentage of plant species are housed in captivity, Brockington and colleagues compared databases cataloguing all known flora to those held by a third of the world’s 3,269 botanical gardens. More than a third of Earth’s 350,699 known plant species are to be found in at least one such institution, the scientists reported. Botanical gardens also house more than 40 per cent of the nearly 32,000 plant species classified as threatened on the Botanic Gardens Conservation International (BGCI) ThreatSearch database. It is by far the world’s most comprehensive list of threatened flora.

IN NUMBERS

350,699 - number of known plant species on earth

32,000 - plant species classified as threatened

3, 269 - number of botanical gardens in the world

40% - amount of space allocated to threatened plant species

10% - area allocated to endangered plants

26% - percentage of plants whose threat status has been assessed

The researchers showed that only 10 per cent of the area in botanical gardens is given over to these endangered plants. They also revealed that earth’s most ancient living flora, so-called non-vascular plants such as mosses and some algae, have been overlooked and neglected, comprising less than five per cent of species under care.
“Non-vascular species are the living representations of the first plants to colonise land,” Brockington said.
“They are essential for understanding the evolution of plants.”

Scientists have so far assessed the threat status of about 26 per cent of the world’s known plant species.