The vegetation history, during Late-glacial and Holocene in the Aosta valley is discussed using palynological data. There are no recent palaeoecological studies of this region. Cores were taken from 9 site situated at different altitudes. The palynological analysis will be supported by the study of macroscopic plant remains.
The aims of this investigation are : 1) to study the vegetation dynamic on a local scale and to compare the data to those for the Swiss and French Alps; 2) to describe the spatial and temporal difference of plant colonization at different altitudes since the Late-glacial; 3) to understand the role played by this region in the migration of taxa (such as Larix, Picea and Abies) after the Late-glacial; 4) to estimate the effect of the anthropogenic impact on the vegetation during the Holocene; 5) to use the results to understand the palaeoclimatology of the alpine region and to assess the possible consequences of the greenhouse effect on the reforestation of the mountain ecosystems. The results will be used for : 1) palaeoenvironmental and palaeoclimatic reconstructions; 2) reassessment of the biostratigraphy of chronologic and the anthropogenic pressure on the biosphere (deforestation and erosion); 3) relate the modern ecosystems to the past; 4) possible management of the biological resources using the historical data obtained; 5) global valutation of the consequences of a possible warming up of the atmosphere on the mountain ecosystems.