In less than a decade, climate change has altered the mix of plants in the French countryside, with some species thriving at the expense of others less tolerant of heat, researchers reported Wednesday.

A study of almost 2,500 plant species from 2009 to 2017, published in Biology Letters, is the first to document the impact of global warming on flora in France over such a short period. 

"There has been a rearrangement of plant communities in France since 2009," Gabrielle Martin from France's Natural History Museum, co-author of the study, told AFP.

"Species that prefer ­warmer temperatures grow more ­abundantly and even settle in new areas."

Slender wild oat (Avena barbata), for example, has flourished across a wide range.

At the same time, however, other plants that prefer cooler climes, such as wild buckwheat (Fallopia convolvulus), have declined over the last decade.

Climate change is clearly the driver in each case, the study found. 

The data underlying the findings was gathered through a citizen science project called Vigie-Flore. 

More than 300 skilled amateur botanists collected data over the nine-year period, noting the presence or absence of France's most common plant species. 

Each participant regularly surveyed one or more plots of one square kilometer each.

About a quarter of the area monitored was artificial land cover, 29 percent was farmland, 16 percent were meadows, and 22 percent was forest.

More than 3,000 sites were catalogued, and the evolution of 550 species tracked.  

The biggest transformation occurred where the rate of temperature increase was highest, the study showed.

"It's the first time that a change in flora on a national scale is detected over such a short period of time," Martin said.

The impact on individual species varied: some blossomed more, others less; some migrated northward, while others grew taller.

Plant species with shorter life cycles adapted more quickly to climate change than perennials, trees or bushes. The similar relationship between size and the ability to adapt has been noted in animals too.

As to whether the change observed is good or bad news is "difficult to say," according to Martin.

Even if biodiversity does not decline, she added, there would certainly be a knock-on effect on the relationship between species.