| Summary: | The Palaeovegetation Mapping Project (generally known as BIOME 6000) was inaugurated in 1994 with the aim of providing global maps describing the vegetation patterns at 6000±500 yr B.P. (on the radiocarbon time scale) and the last glacial maximum (defined as 18,000±1000 yr B.P. on the radiocarbon time scale, equivalent to 21,000 yr B.P. on the calendar time scale) for use by the modelling community. The BIOME 6000 project has used a standard methodology to map vegetation patterns using fossil pollen and plant-macrofossil data from individual sites. The taxa represented in the pollen or plant-macrofossil assemblages are first allocated to plant functional types (PFTs) on the basis of the life form, leaf form, phenology and bioclimatic tolerance of the plant species included within the taxon. Because of the lack of taxonomic resolution in pollen identification, some taxa can be classified into more than one PFT. Biomes (i.e. major vegetation types at a regional scale) are defined by combinations of PFTs, where these combinations usually include both characteristic and dominant groups. Some PFTs which are known to occur within a given biome are not included in the biome definition because they occur in too many biomes to provide discriminatory power. Once the taxon to PFT and PFT to biome classifications are made, the affinity of pollen or plant-macrofossil assemblages from individual sites for each biome is calculated. Each assemblage is allocated to the biome for which it has the highest affinity. In cases where the assemblage has equal affinity for more than one biome, which can occur when one biome is defined by a subset of the PFTs that characterise another biome, the assemblage is allocated to the biome defined by the subset. For more information, see Also see Harrison, S. P., and I. C. Prentice. 2003. Climate and CO2 controls on global vegetation distribution at the last glacial maximum: analysis based on palaeovegetation data, biome modelling and palaeoclimate simulations. Global Change Biology 9, 983-1004.
|
|---|