From the text...'Disturbance plays a major role in shaping and maintaining many of the Earth's terrestrial ecosystems. In fact, many ecosystems depend on fire for their very existence. Global Change is expected to result in changed distribution of current ecosystems, changed composition of those ecosystems, and in creation of new ecosystems. The International Geosphere Biosphere Program (IGBP), through the Core Projects Biospheric Aspects of the Hydrological Cycle, International Global Atmospheric Chemistry, Global Change and Terrestrial Ecosystems and International Global Atmospheric Chemistry, Biomass Burning Working Group, recognized that disturbances need to be included in the modeling efforts of each project. Disturbance from fire, land use and other facts may be as important as climate change in shaping future landscapes (Weber and Flannigan 1998). Three main themes were recognized: impact of disturbance on carbon pools, vegetation change, and feedbacks to the atmosphere. In June 1998, a workshop was held in Potsdam, Germany to develop a strategy to introduce disturbance into dynamic global vegetation models...While this workshop limited itself to fire, a great deal of consideration was given to the fact that the model shell must be able to include other disturbances in the future. As a result, the strategy was to focus on a hazard function which would lead to effects of disturbance. The hazard function is basically a probability statement of risk of effects. This approach seems equally valid for all forms of disturbance...Dynamic Global Vegetation Models (DGVM) contain several common elements or modules. These include: (a) some form of rule base to determine the plant functional types (PFT) that can be supported at a site or pixel, such as evergreen conifer or deciduous broad leaf trees; and in some cases, (b) a module to calculate the biogeochemical cyles and carbon and nutrient pools; and (c) a disturbance module to simulate the impacts of fire and other disturbances on vegetation structure and carbon balance, as well as other modules such as biogeochemical cycles, nutrient status and bi-directional feedbacks between the biosphere and the atmosphere.' ©IAWF Abstract reproduced from the International Journal of Wildland Fire (Fosberg, M.A., W. Cramer, V. Brovkin, R. Fleming, R. Gardner, A.M. Gill, J.G. Goldammer, R.E. Keane, P. Koehler, J. Lenihan, R. Neilson, S. Sitch, K. Thornicke, S. Venevski, M.G. Weber, and U. Wittenberg, 1999) with the kind permission of CSIRO PUBLISHING on behalf of the International Association of Wildland Fire. (http://www.publish.csiro.au/journals/ijwf/). Abstract may not be reproduced in any other publication, whether printed or electronic, without the prior written permission of CSIRO PUBLISHING.