Bioclimatic distribution of vegetation for general circulation model studies

Abstract

Four global bioclimatic schemes which use climate to determine the distribution of vegetation are evaluated. Only 38% to 40% of the observed land surface, mapped as thirty‐one vegetation types, could be replicated by applying the four schemes to two global climate data sets. The simulations are significantly improved by further subdividing and regrouping the climates defined by the schemes. In addition, the observed vegetation types are regrouped to better reflect both similarity of climate and similarity of attributes which affect exchanges of atmospherically important gases. With these alterations, 77% of the predicted vegetative landscape corresponds with the distribution of present vegetation. Each observed vegetation type is analyzed in terms of the success with which it can be resolved from climate. This simple coupling of vegetation and climate allows the distribution of simulated vegetation to adjust to present or perturbed climate. It is a rudimentary interactive atmosphere‐biosphere in which the climatically determined distribution of vegetation forms the basis of predicting or prescribing atmosphere‐biosphere exchanges. The climate parameters used, the grouping of vegetation types, as well as the resolution and scope of the revised bioclimatic scheme, have been designed to be used with general circulation models.