MODELING TEMPORAL VARIABILITY OF BOREAL LANDSCAPE AGE-CLASSES UNDER DIFFERENT FIRE DISTURBANCE REGIMES AND SPATIAL SCALES

Natural fire disturbances are known to have had a significant role in boreal forests at the stand and landscape levels. Van Wagner's exponen tial model gave useful insight into the theoretical dynamics of the fo rest age distribution in fire-disturbed landscapes. His work motivated extensions to the theoretical model and more empirical tests in a var iety of landscapes. The empirical tests have had mixed results. While Van Wagner stated that the model is theoretical, and warned that one s hould expect to fmd variability in landscapes in any case, there is th e risk that the exponential model can be misunderstood or inappropriat ely applied if variability is not adequately considered. An existing t heoretical simulation model of landscape fire disturbance (FLAP-X) was used to explore the temporal variability of two selected landscape at tributes: the percentages of old growth and recently disturbed area. I t was found that under characteristic boreal fire disturbance regimes, these percentages can vary widely over time even at large spatial sca les due to the spatiotemporal autocorrelation of disturbances. Some of the consequent implications of managing a landscape for naturalness a t multiple spatial scales when there is a wide range of conditions tha t can be considered natural are discussed.