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The research headed up by AgroParisTech's Professor Lenoir, and published in June's issue of Science, studied 171 mountain plant species.  The study found a significant number of plant species had risen to a higher altitude, on average they had risen about 29m per decade.

It has already been observed that climate change is affecting plants at the edge of where they can survive, but studies of plants at more moderate altitudes have not been studied before.  This study exploited a CNRS database of thousands of floral inventories from all the French mountain forests since the beginning of the 20th century. This database made it possible to compare the altitudinale distribution each of the 171 species studied between the periods 1905-1985 and 1986-2005 for a range of altitudes from 0 to 2600m in the moderate and Mediterranean areas representative of the Western-European mountains. The limit of 1985 between the two periods was selected because the annual average temperature increased of almost 1°C in the zone studied around this pivotal date.

The study showed a significant rise in altitude for the majority of the plants, at about 29m per decade. This rise is the same whatever the studied altitude and the thermal preferences of the plants.  The researchers found that the species moved, to a higher altitude from their preferential habitats to preserve the temperature which is appropriate best for their development, reproduction, and survival.

Not all the species do migrated at the same speed: the plant species with a shorter lifespan, like the herbaceous plant (e.g. grasses and ferns), tend to migrate upwards more quickly than trees or the shrubs. The herbaceous plants were able to take advantage of their short life cycle to move more quickly.  Trees however, because of their short life cycle, have only had one or two generations to move.

Taken as a whole, these results prove that plants are migrating with climate change to preserve the temperatures necessary for their survival. Various speeds of migration between trees and herbaceous plants will lead to a change of the composition of the vegetable communities and their relations with the animal species that interact with them.