Ecosystem management in the context of large, infrequent disturbances

Large, infrequent disturbances (LIDs) can have significant impacts yet seld om are included in management plans. Although this neglect may stem from re lative unfamiliarity with a kind of event that rarely occurs in the experie nce or jurisdiction of individual managers, it may also reflect the assumpt ion that LIDs are so large and powerful as to be beyond the ability of mana gers to affect. However, some LIDs can be affected by management, and for m any of those that cannot be affected, the resilience or recovery of the sys tem disrupted by the disturbance can be influenced to meet management goals . Such results can be achieved through advanced planning that allows for LI Ds, whether caused by natural events, human activities, or a combination of the two. Management plans for LIDs may adopt a variety of goals, depending on the nature of the system and the nature of the anticipated disturbance regime. Managers can choose to influence (a) the system prior to the distur bance, (b) the disturbance itself, (c) the system after the disturbance, or (d) the recovery process. Prior to the disturbance, the system can be mana ged in ways that alter its vulnerability or change how it will respond to a disturbance. The disturbance can be managed through no action, preventive measures, or manipulations that can affect the intensity or frequency of th e disturbance. Recovery efforts can focus on either managing the state of t he system immediately after the disturbance or managing the ongoing process of recovery. This review of the management implications of LIDs suggests t hat management actions should be tailored to particular disturbance charact eristics and management goals. Management actions should foster survival of residuals and spatial heterogeneity that promote the desired recovery patt ern and process. Most importantly, however, management plans need to recogn ize LIDs and include the potential for such disturbances to occur.