MOVEMENT TO HIGHER ELEVATIONS OF THE RANGE OF TEMPERATE FOREST PLANT SPECIES IN CONNECTION WITH RECENT GLOBAL WARMINGOriginal Title (non-English) LA REMONTEE DE LA DISTRIBUTION ALTITUDINALE DES ESPECES VEGETALES FORESTIERES TEMPEREES EN LIEN AVEC LE RECHAUFFEMENT CLIMATIQUE RECENT [French]

摘要

Movement of the latitudinal distribution of species towards the poles and attitudinal distribution towards the tops of mountains are generally associated with changes observed at the margins of distribution under extreme climatic conditions. However, changes of this type in the heart of the distribution area under optimal climatic conditions have been poorly investigated for forest plant species in a temperate climate. Using national data bases, we studied this type of movement in montane areas where the study of changes in distribution is made easier by the fact that, as altitude increases, temperature conditions vary rapidly and in the same direction. On the scale of all French mountain ranges, our results show that the attitudinal optimum for forest plant species has climbed by 30 m every decade since the middle of the 1980's and that this upward drift is more easily detected in species with short reproductive cycles. These results provide additional material that confirms that species are moving to higher ground, not just at the margins but also in the heart of their range. However, our results also show that the ascent observed is half as large as the predicted change under the effect of global warming alone, suggesting that limiting processes may be at work.