Modeling the long-term effects of fire suppression on central hardwood forests in Missouri Ozarks, using LANDIS

Abstract

Fire suppression has been found to dramatically change fire regimes, lead to accumulation of fuels, and alter forest composition and species abundance in the Central Hardwood Forests in the Missouri Ozarks, United States. After a half century of fire suppression, fire hazards have increased to a high level and high intensity fires are more likely to occur. We used LANDIS, a spatially explicit landscape dynamics model, to simulate the long-term effects of fire suppression on forests in Missouri Ozarks. Specifically, we examined to what extent fire suppression would affect fuel loads and fire hazards, and how fire suppression would affect forest tree species abundance. Using a spatial modeling approach, we conducted 200-year simulations of two management scenarios: (1) a fire suppression scenario circa 1990s and (2) a historic fire regime scenario prior to fire suppression, with a mean fire-return interval of 14 years. Under the fire suppression scenario, the simulation showed that both fine and coarse fuels were at a medium-high level after a few more decades of fire suppression. Fire hazard also rapidly increased to a medium-high level within a few decades. After one century of fire suppression, simulated fire intensity increased to a dangerous level, with more than 3/4 of the fires at a medium-high intensity level. Fire suppression also led to distinct changes in species abundance; the pine and oak–pine forests which used to dominate the study area prior to fire suppression were replaced by mixed-oak forests. This study suggests that it may be desirable to re-introduce frequent fire. By greatly increasing the use of fire over current management levels, our simulation suggests less accumulation of dangerous fuels, reduced fire hazard, and decreased occurrence of high intensity fires. Results imply that frequent fire would greatly increase the abundance of fire-resistant species (e.g., shortleaf pine) and decrease the abundance of more fire-sensitive species such as red oaks. Such a compositional shift should also decrease the recent phenomenon of widespread oak decline events.