Figure 19.3. Positive and negative feedbacks controlling fire processes in tropical forests (Cochrane 2003). Positioning of processes or activities indicates whether they occur within or outside of the forest (green shading). Items bordered in red control fire occurrence or behavior, while items in brown modify the potential fire environment. Green indicates ecosystem processes that act in opposition to fire, specifically regrowth, canopy closure and decay of fuels. The management efforts and interventions box indicates how and where human actions can diminish tropical forest fires. Climate change encompasses the effects of increased CO2 , land cover change, and aerosol loading the net effect of which is regional drying in the tropics (Ramanathan et al. 2001, Kaufman et al. 2002, DeFries et al. 2002). Changes in the amount or intensity of any of the processes or activities will change the strength of their forcing functions (arrows) but not their direction. For example, increasing education of rural people in better fire management techniques causes a reduction of fire ignitions entering the forest which, in turn, reduces the level of interaction with forest fuels that leads to increased fire severity. Fire ignitions, however, are always positively related with increasing fires. |