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(Paul Starosta/Stone/Getty Images)

The World's Marvellously Freaky Carnivorous Plants Are in More Trouble Than We Knew

27 SEPTEMBER 2020

It's hard to fathom that carnivorous plants exist. When Charles Darwin first described how a Venus flytrap worked, calling it "one of the most wonderful [plants] in the world", some people simply didn't believe him.

 

Today, just as we've come to appreciate the gruesome nature of these remarkable predators - which can capture and eat flies, rats, salamanders, or the droppings from shrews - they're now fast disappearing.

The first systematic assessment of carnivorous plants around the world has found a quarter of all known species are at risk of imminent extinction.

"Without urgent action, we stand to lose some of the most ecologically unique, evolutionary interesting, and horticulturally-celebrated species on the planet," scientists warn

As of January 2020, researchers have described roughly 860 species of carnivorous plants in total, and while habitats vary, these plants are usually found in wetlands.

Unfortunately, wetlands are also some of the most vulnerable to clearing, logging, and climate change, which puts the future of carnivorous plants at odds with human development and our emissions.

In recent years, pitcher plants and Venus fly traps have received more interest from scientists and the public, but their conservation status in many cases is unknown.

In 2011, a review of carnivorous plant species found habitat loss from agriculture, the collection of wild plants, pollution, and changes to natural systems were the biggest threats. At the time of the research, however, only 600 species had been described; comprehensive data were available for only 48 species. 

 

In the years since, we've come to understand carnivorous plants a lot better, and the implications have scientists concerned. 

If nothing changes, climate predictions suggest nearly 70 percent of modelled species will be adversely impacted by climate changes. By 2050, several species are expected to lose 100 percent of their potential range.

The first conservation examination since 2011 now shows us well on the way to that reality.

Compiling full or partial data from all known species, researchers found carnivorous plants were most diverse "in some of the most heavily cleared and disturbed areas of the planet," including Western Australia, Southeast Asia, the Mediterranean, Brazil, and the eastern United States.

In the end, the authors say eight percent of all species (69 species in total) are critically endangered, 6 percent are endangered, 12 percent are vulnerable, and another 3 percent are near threatened.

"Globally speaking, the biggest threats to carnivorous plants are the result of agricultural practices and natural systems modifications, as well as continental scale environmental shifts caused by climate change," says botanist and ecologist Adam Cross from Curtin University in Australia.

 

"In Western Australia, which harbours more carnivorous plant species than any other place on Earth, the biggest threat remains the clearing of habitat to meet human needs, resulting hydrological changes, and of course the warming, drying climate trend that affects much of Australia."

Even if these plants could flee from human development and the effects of climate change, many have nowhere to go. Carnivorous plants are highly specialised, and as such, many species occupy very specific niches. 

This extreme restriction means many carnivorous plants are moving towards the edge of extinction in a rapidly changing world.

In the current global analysis, at least 89 species are known from only a single location. Worldwide, almost a quarter of all species are facing three or more existential threats, including global climate change, the clearing of land for agriculture, mining and development, and illegal poaching. 

While the plucking and selling of precious carnivorous plants is illegal in most parts of the world, in economically deprived areas it's hard to stop black markets from popping up. The study authors say these trades remain an "open, tolerated secret".

 

"Everyone has mobile phones and the internet for eBay, so there's a massive trade in the world of rare plants, and it gets bigger and bigger every year," one naturalist explained to the BBC in 2016.

"People in Europe and North America want specifically different ones, which drives people to go up the mountains, rip them out and bring them back to sell locally and internationally."

So hungry are carnivorous plant collectors, they will sometimes pay US$1,000 for a single plant. It's not unusual for requests about the plants to roll in to researchers and photographers within days or even hours of a new photograph reaching the internet. All the authors of the present work have experienced such requests for these rare plants.

There have even been tragic instances when entire populations have been poached within days of their discovery. 

While Venus fly traps are popular among collectors, tropical pitcher plants were found to be the most at-risk from poaching, especially in Malaysian Borneo, Indonesia, and the Philippines, which all rank in the top six worldwide for most critically endangered carnivorous plants. Brazil is number one, with 13 species facing critical extinction.

To prevent these plants from disappearing in the near future, scientists say we need to take immediate action.

"Conservation initiatives must be established immediately to prevent these species being lost in the coming years and decades," argues taxonomist and field botanist Alastair Robinson from Royal Botanic Gardens Victoria in Australia.

"Urgent global action is required to reduce rates of habitat loss and land use change, particularly in already highly-cleared regions that are home to many threatened carnivorous plant species, including habitats in Western Australia, Brazil, southeast Asia and the United States of America."

The cultivation of rice and oil palm are destroying habitats in Southeast Asia, while logging and development in Australia encroaches on native flora. In fact, Western Australia's 'wheatbelt' has one of the highest rates of habitat clearance on the planet.

In South Africa, extreme drought has left many wetland ecosystems unusually dry, and high intensity and frequent fires in Brazil are wiping out precious wilderness when humans don't get there first.

One region in Brazil is said to harbour at least 70 species of carnivorous plant. It's also headed towards ecological collapse thanks to climate change, which is expected to remove up to 82 percent of suitable habitat by 2070.

But all is not lost. Scientists say if we can shift our attitudes and actions as a global community, shutting down the illegal market of carnivorous plants and implementing better development regulations, we could save at least some of these species.

Carnivorous plants are pioneers, the authors say, and when they are exposed to wet soil, they stick to it like a fly in a trap, producing large quantities of seeds to colonise new areas.

"Thus, while suitable habitat remains and natural ecological processes can be maintained, there is hope for [carnivorous plants] to survive (in) the Anthropocene," the authors conclude.

The study was published in Global Ecology and Conservation