[From the Introduction] Fire as a landscape process is of broad interest to ecologists and land managers. Fires alter forest age-distributions (Heinselman, 1973; Van Wagner, 1978), are sensitive to climate (Balling et al., 1992, Swetnam and Bettancourt, 1990; Swetnam, 1993; Timoney and Wein, 1991), can be manipulated by fire suppression (Baker, 1992; Barrett, 1994), and affect directions for land management policy (Hunter, 1993; Lesica, 1996; Huff et al., 1995; Johnson et aI., 1995; Omi, 1996). Fire models are used for ecological research into spatial disturbance and recovery patterns (Turner et al., 1989; Green, 1989; Ratz, 1996; Boychuk et al., 1997), forest landscape dynamics (Keane et al., 1996; Mladenoff et al., 1996; Boychuk and Perera, 1997; Li et al., 1997), and fire planning (Kessell, 1976; Methven and Feuenkes, 1988; Beer, 1990). For ecological modeling, fire or disturbance patterns have usually been simulated by directly applying stochastic algorithms to modify spread directions and rates (Turner et al., 1989; Green, 1989; Baker et al., 1991; Mladenoff et al., 1996; Gardner et al., 1996), or to bum a proportion of the landscape area (Ratz, 1996; Li et al., 1997). Another approach is to focus on simulating the fire processes so that the cause-and-effect relationships for a given pattern can be studied. There is great interest in analyzing landscape patterns that result from fire to determine how those patterns relate to ecological theories (Romme, 1982; Baker, 1992; Suming et al., 1988) . Because many landscape patterns are produced by variation in fire behavior, a mechanistic simulation of fire behavior and fire growth is useful for explaining how, why, and when such patterns can form. Mechanistic simulation models (e.g., process models) try to represent a system as a set of fundamental processes that each describe cause and effect relationships between physical variables. Often, empirical relationships must substitute for individual processes that are not understood well enough for a more detailed description. The general mechanistic approach is useful for studying fire patterns because it allows an evaluation of: (i) the role of specific environmental factors in creating patterns of fire behavior and effects, (ii) the effects of each component process on the simulated fire pattern, and (iii) how spatial and temporal dependencies affect fire patterns.