Binkley, D. (Rapp.), Becker-Heidmann, P., Clark, J. S., Crutzen, P. J., Frost, P., Gill, A. M., Granström, A., Mack, F., Menaut, J.-C., Wein, R. W., Van Wilgen, B. (1993): Group report: Impact of fires on ecosystems. – In: Crutzen, P. J., Goldammer, J. G. (Hg.): Fire in the environment, S. 359–372. Dahlem workshop reports. Wiley, Chichester
The impacts of fires on ecosystems are variable across gradients in time and space. Frequent, low-intensity fires have substantially different effects from rare, high-intensity fires. Small fires may lead to mosaics of ecosystems of differing composition and structure whereas large fires tend to homogenize landscapes. The current state of knowledge is typified by detailed characterizations of the impacts of particular fires on particular sites from which generalizable insights may not emerge. Changes in vegetation structure and species composition strongly influence the flammability of an ecosystem as well as gaseous emissions when ecosystems burn. Such changes in structure and composition are driven by a wide array of factors operating across a range of scales in time and space. Extrapolation across large regions, or long periods of time, is likely to be much more complex than simple multiplication. An understanding of the factors affecting fires across scales, and the changes these factors cause, is fundamentally important to estimations of gas emissions from fires at both local and regional scales.
Our discussions, within a framework of time and space, focused on four key features of fires across these scales:
– Impacts of fire-related spatial patchiness,
– Constraints on the predictability of fires and the impacts of fires,
– Interactions and feedbacks between vegetation and fires, and
– Long-term effects of fires on fluxes of carbon, nitrogen, and phosphorus.
We hope this approach will help in the development of more coherent characterizations of the roles of fire and will provide a foundation for the extrapolation across scales that is necessary for regional and global problems.