Summary Report No. 3


Using Plant Functional Types in a Global Vegetation Model

W. Cramer (September 1994)

Global vegetation models have been developed under the assumption that climate is the dominating driving force of vegetation composition and structure, and that the broad-scale pattern of global vegetation is in equilibrium with climate. Non-climatic habitat factors, such as soil parent material, and competition limit the applicability of such models, but they have proven to be useful at a global scale. The concept of plant functional types was first introduced by E.O. Box into global vegetation models, using a scheme with 90 different types. A more recent model, BIOME, reduces this number to only 14 types, using more mechanistically defined bioclimatic indices, fewer parameters and an improved database. With the BIOME model, realistic global maps of potentially natural vegetation can be derived. Using high-resolution, present day climate data along with smoothed climate change anomalies derived from atmospheric general circulation models, climatic change impact scenarios about equilibrium shift of the major biomes can be produced.