Extinction threat for Wet Tropic possums

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Ringtail opossum populations in the Wet Tropics of Queensland could be wiped out in less than three decades as climate change, including extreme heat waves, drives population declines.

Populations at lower elevations have declined to “local extinction” as opossums that evolved in cool rainforests are forced to higher elevations, said James Cook University professor Stephen Williams.

“It climbed up the mountain, we saw them disappear at 600 meters, then almost disappear at 700 meters and at 800 meters they are less than 50% of the abundance they had before,” he said. declared.

Most of the mountains in the region are just over 100 meters at their peak.

“They’re just being pushed up with few places to go…nowhere to really go,” says Professor Williams.

His paper with PhD student Alejandro de la Fuente analyzed a long-term ringtail population survey conducted between 1992 and 2021 in the humid tropics.

He found that the negative impacts of climate change, including extreme heat waves, have led to rapid declines in ringtail opossum populations over the past three decades.

“Somewhere between 2010 and 2014…things just started to get too bad, and the combination of rising temperatures and increased frequency and intensity of heat waves just caused this exponential decline. “said Professor Williams.

“Almost all future models now, regardless of the (emissions) reduction scenario, predict that there will be very severe impacts.”

In heat wave years, the analysis suggests that there is likely both an increase in mortality rate and a decline in reproductive rates.

“We haven’t seen opossums falling from trees…but what we do know is that every time we have a year or two in a row of a heat wave, the numbers really plummet,” the professor said. Williams.

Four species of ringtail possums live in the humid tropics – the lemuroid ringtail, green ringtail, Herbert River ringtail, and Daintree River ringtail.

The findings led him to designate the Lemuroid Ringtail opossum as endangered through the Environmental Protection and Biodiversity Conservation Act.

The impact of climate change is not limited to opossums, and many of the unique birds that live in the rainforest have declined by 30-50% of their total population, and have also been pushed to higher altitudes.

The analysis suggests that even a moderate reduction in carbon emissions would help reduce extinction rates of all species in the humid tropics from over 50% of species to as low as 5%.

Long-term monitoring and “lots” of fieldwork are essential to understanding ecosystem health, but funding is not secure.

Funding for the region “has really been reduced” as political pressure pushes further towards the fate of the Great Barrier Reef, Prof Williams said.

“We have these two incredible World Heritage areas, the Great Barrier Reef and the Wet Tropics, side by side,” he said.

“These are two great tourist attractions, both worth billions and billions of dollars in ecotourism.

“The rainforest has been a bit of a poor cousin compared to the reef.”

Professor Williams said it was also essential to explore adaptation options for species in the World Heritage area.

“What this article shows us is that there is a big difference between the impacts of heat waves and long-term changes,” he said.

“Some species are most affected by heat waves while others are declining in association with gradual climate change.”

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