Plants and Tress Head for the Hills to Escape Global Warming

Trees, shrubs and other plants that make up mountainside forests are shifting to higher ground to escape the warming climate, researchers have found.

Common species found on mountain ranges across Europe have steadily spread to higher altitudes during the 20th century, thriving on land that is on average 29m higher each decade, records show.

French scientists who examined plant records for six mountainous regions, including the western Alps and northern Pyrenees, said their findings point to the dramatic affect climate change is having on plant life.

"For the first time we have showed that climate change is already having a significant effect on a large set of plant species," said Jonathan Lenoir, lead author on the study at AgroParis Tech, a consortium of French academic institutions.

The study is particularly significant because the mountain ecosystems are not regarded as especially sensitive to climate change, unlike many others regions on the planet.

Writing in the US journal Science, the researchers describe how parts of France have witnessed greater temperature rises in the 20th century than the global average. In some alpine regions, temperature rises have exceeded 0.9C over the period.

In the study, Lenoir and his team examined 3991 historical inventories of plant life that had been conducted between 1905 and 1985 or over a later period from 1986 to 2005. The surveys showed how the distribution of 171 different plant species varied with time across six mountain ranges, including the Western Alps, the Northern Pyrenees, the Massif Central, the Western Jura, the Vosges and the Corsican range. All of the plants grew between sea level and an altitude of 2,600m.

The surveys showed that as temperatures increased over the decades, the altitudes plants thrived at also rose, with short-lived species such as grasses and ferns heading for higher, and cooler ground, more quickly than long-lived species such as trees and shrubs.

Plants that grow almost entirely on mountainsides, such as side bells wintergreen (Orphilia secunda), moved more than plants that are also found in lowlands, such as the paris herb. Fast breeding species were also found to have moved to higher latitudes than slow-breeding woody plants, such as the white beam (Sorbus aria).

Not all of the plants included in the study shifted to higher altitudes. Of those studied, 53, or nearly one third moved down mountainsides to lower land, the surveys revealed.

"Our results show that species displayed different rates of movement, behaving in a seemlngly idiosyncratic way in response to climate change," Lenoir said.