Weather 
Up to one in six plant species could be wiped out within 75 years, warns a new study.
Researchers found that 7% to 16% of global plant species studied are expected to lose more than 90% of their range by 2100 under current climate change projections.
The ecological modeling study shows that many plants face a “high risk” of extinction by the end of the century — including eucalyptus — under current climate change projections.
High extinction rates are projected in southern Europe, the western United States and southern Australia- posing risks to both ancient and economically vital plant species.
But some areas will actually see an increase in species richness over the next few decades, according to the study.
The American research team say habitat loss due to climate change is expected to drive extinctions, rather than a plant’s ability to shift locations or “keep pace” with global warming.
The findings, published in the journal Science, suggest that conservation strategies focused on assisted migration, where people facilitate species range shifts, may not reduce global plant extinctions induced by climate change.
But researchers say combining such efforts with restoration and protecting climate change havens may be more effective.
Study senior author Professor Xiaoli Dong, from the University of California, Davis, said: “We found that what causes extinction is not that plants aren’t moving fast enough.
“It is that a large amount of suitable habitat by the end of the century is going to be gone.
“If our priority is reducing the extinction rate of plant species, aggressively cutting our emissions will be much more important than other actions.”
The researchers wanted to understand how plants are going to respond to warming over the next few decades.
They used a database of nearly 68,000 plant species, which make up 18% of the world’s flora.
The team projected the distributions of the plants through to 2100 and accounted for uncertainties, arriving at an extinction rate of 7% to 16% across emissions scenarios.
Dong said most previous models projecting extinction rates didn’t incorporate the speed of range shifts — how fast species can actually move as the climate changes.
That addition showed that habitat loss, not range shifts, drives extinction rates under climate change.
Among species facing extinction, according to the research, are eucalyptus in Australia, a genus that covers three-quarters of the continent’s native forests and is crucial to the timber industry and indigenous culture.
Another is California’s spikemoss — one of the oldest surviving lineages of vascular plants, dating back over 400 million years.
But the researchers say range shifts can enhance local species richness, which refers to the number of species in a given place.
Around 28% of Earth’s surface will see an increase in local species richness as plants move in response to climate shifts, according to the study.
Study first author Dr. Junna Wang, now at Yale University, said: “Areas likely to gain species richness are mostly in wet regions or those projected to become wetter such as the eastern United States, India, South East Asia and southern South America.
“In contrast, the western United States, much of Europe and Australia are expected to lose diversity as many species’ ranges shrink.”
Dong said: “This grand reshuffling of plants across the globe will require new ways of thinking about conservation and what ‘belongs’.
“Things are going to change, and we have to adapt.”
She added: “Some of these species will be meeting together for the first time.
“We will see novel interactions. The outcome of that is hard to predict.
“Things will be different from what we remember 40 to 50 years ago.”
The study also highlights an increasingly important role for seed banks, botanical gardens and places that can serve as climate refuges for plants whose genetic, medicinal and cultural value may otherwise be lost.
