| This dissertation studies four methods for recommending mean fire intervals (MFIs) for five southern California plant communities. The AHP procedure uses a hierarchical prioritization system called the Analytic Hierarchy Process (AHP) to elicit recommendations from experts in a formulaic manner. Experts make pairwise comparisons between nine criteria (wildfire probability, fire management costs, smoke emissions, flood hazard, sediment yield, nitrogen runoff, mean annual runoff, biodiversity, and herbivore forage) to recommend MFIs for each plant community. The AHP/SIMPPLLE procedure uses a distributed, stochastic ecological model (SIMulating Patterns and Processes at Landscape scaLEs) to assess likely impacts of recommended MFIs on vegetative structure and composition, air quality, wildfire probability, and management costs over a 100-year period. The AHP/WEPP procedure applies the recommended MFIs to a surface runoff and soil loss model (the Water Erosion Prediction Project). The MAGIS procedure uses a computerized decision support system (Multiresource Analysis and Geographic Information System) to independently establish optimal MFIs based on six criteria, four derived from SIMPPLLE and two derived from WEPP output. Results of all procedures are compared and discussed. As part of this process I introduce the concept of a fuel load year (FLY), which is a calendar year lengthened or shortened by climate-induced variations in vegetative fuel load.;The case study location is the southeast portion of the Angeles National Forest on the southern flank of the San Gabriel Mountains north of Los Angeles. The combined results suggest that fairly short mean prescribed burn intervals (MPBIs)---and thus even shorter MFIs, somewhat shorter than those recommended by experts---may provide a good balance between the criteria considered, at least for this study area.;This study should not be taken as a management proposal for this area, but as a set of considerations for incorporation into decision-making that could generate a viable management plan for this and other landscapes. Should a pattern of MFIs ultimately be applied here or elsewhere, such application could require the use of prescribed burns if the current MFI is found to be too long, or it could involve fire suppression alone if the current MFI is too short. |
