Developing Fire Management Strategies in Support of Adaptive Management at Tejon Ranch , Ca
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DEVELOPING FIRE MANAGEMENT STRATEGIES IN SUPPORT OF ADAPTIVE MANAGEMENT AT TEJON RANCH , CA Submitted in partial satisfaction of the requirements for the degree of MASTER OF ENVIRONMENTAL SCIENCE AND MANAGEMENT at the BREN SCHOOL OF ENVIRONMENTAL SCIENCE & MANAGEMENT AUTHORS : SEAN BAUMGARTEN , ASHLEY GILREATH , ELLIE KNECHT , ADAM LIVINGSTON , NICOLE PHIPPS , AND ANDREW PROSSER FACULTY ADVISOR : FRANK DAVIS April 2012 DEVELOPING FIRE MANAGEMENT STRATEGIES IN SUPPORT OF ADAPTIVE MANAGEMENT AT TEJON RANCH , CA As authors of this Group Project report, we are proud to archive it on the Bren School’s website, such that the results of our research are available for all to read. Our signatures on the document signify our joint responsibility to fulfill the archiving standards set by the Bren School of Environmental Science & Management. _________________________________ SEAN BAUMGARTEN _________________________________ ASHLEY GILREATH _________________________________ ELLIE KNECHT _________________________________ ADAM LIVINGSTON _________________________________ NICOLE PHIPPS _________________________________ ANDREW PROSSER The mission of the Bren School of Environmental Science & Management is to produce professionals with unrivaled training in environmental science and management who will devote their unique skills to the diagnosis, assessment, mitigation, prevention, and remedy of the environmental problems of today and the future. A guiding principle of the School is that the analysis of environmental problems requires quantitative training in more than one discipline and an awareness of the physical, biological, social, political, and economic consequences that arise from scientific or technological decisions. The Group Project is required of all students in the Master’s of Environmental Science and Management (MESM) Program. It is a three-quarter activity in which small groups of students conduct focused, interdisciplinary research on the scientific, management, and policy dimensions of a specific environmental issue. This Final Group Project Report is authored by MESM students and has been reviewed and approved by: ________________________________ FRANK DAVIS, PH.D. April 2012 TABLE OF CONTENTS List of Figures…….…………………………………………………………......……iv List of Tables…….…………………………………………...……………………....vi Acknowledgments………………………………………………...………………....vii Abstract……………………………………………………………………………..viii I. Executive Summary……….………………………………………………….1 II. Project Significance……….………………………………………………….2 III. Objectives……….…………………………………………………………….5 IV. Past and Present Fire Regimes………………………………………………..6 A. Fire History Trends……………………………………………………....…6 B. Fire Return Interval Departure Analysis…………………………………...10 C. Fire Regimes in the Ranch’s Major Ecological Communities………….….16 V. Management Approaches and Recommendations………………….…….….30 A. Management Approaches Considered……………………………….....….30 B. Modeling of Management Scenarios Using LANDIS-II…..…………........36 C. Cost Analysis……………………………………………….………...…....45 D. Management Recommendations…………………………………………...49 VI. Recommendations for Future Research……………………………………...75 VII. Conclusion………………………………………………………………..….77 VIII. References…………………………………………………………………...78 Appendix A: Background on the Ranch’s Ecological Communities……….………106 Appendix B: Additional Background on Ranchwide Drivers of Fire………………146 Appendix C: Background on FRID Analysis and Community-Specific FRID Maps ………………………………………………………………………………………152 Appendix D: Full Description of LANDIS-II Methods and Additional LANDIS-II Results……………………………………………………………………………....160 Appendix E: Additional Background on Cost Analysis……………..……………..170 Appendix F: Background on Additional Wildlife Species Affected by Fire…..…...171 iii LIST OF FIGURES Figure 1: Location and major vegetation types of Tejon Ranch. ................................. 4 Figure 2: Recorded fires on Tejon Ranch. More recent fires obscure older fires. Only fires occurring between 1950 and 2010 were used in the analysis. .............. 6 Figure 3: Recorded fires in USFS ecoregion subsections which converge on Tejon Ranch. More recent fires obscure older fires. Only fires occurring between 1950 and 2010 were used in the analysis. ...................................................................... 7 Figure 4: Number of fires each year since 1950. A Poisson regression was used to represent the relationship between number of fires and year. ............................... 8 Figure 5: Size and season of fires occurring on Tejon Ranch since 1950 (excludes prescribed burn treatments). The size of each circle reflects the relative area burned. The largest fire represented is 17,644 acres. Only fires occurring between 1950 and 2010 were used in this analysis. .............................................. 9 Figure 6: Sources of fire ignitions on Tejon Ranch since 1950, derived from CAL FIRE data and Tejon Ranch prescribed fire records. ........................................... 10 Figure 7: Tejon Ranch FRID map with maximum values. FRID is expressed as the number of intervals since the last fire. ................................................................. 14 Figure 8: Tejon Ranch FRID map with median values. FRID is expressed as the number of intervals since the last fire. ................................................................. 15 Figure 9: Age of chaparral stands (excluding Brewer’s oak) on the Ranch, measured as time since last fire. Approximately 4,000 acres of chaparral burned in prescribed fire treatments in 1987, 1988, 1989 (21 to 40 year age class) and 160 acres in 1992 (0 to 20 year age class). ................................................................. 28 Figure 10: Region of interest (enlarged on right), showing conifer forests in green. 38 Figure 11: Management areas within the region of interest. ..................................... 40 Figure 12: Fire statistics comparing all 10 scenarios. The top letter represents No management (N), Thin only (T), or Thinning followed by prescribed Burns (TB). The bottom letter represents the climate scenario with Current climate (C), the GDFL scenario, and the PCM scenario. .............................................................. 41 Figure 13: Annual probability of burning over the full 50-year model duration for each scenario, averaged across 10 replicate simulations for each scenario. ........ 43 iv Figure 14: Annual probability of burning in management areas under current climate. ............................................................................................................................. 44 Figure 15: Targeted Conifer Treatment Areas ........................................................... 48 Figure 16: Cost curve for conifer management strategies. ......................................... 49 Figure 17: Cost of various sizes of barbed wire fence plots. ..................................... 67 Figure 18: Median FRID map highlighting grassland systems. .............................. 155 Figure 19: Median FRID map highlighting oak systems. ........................................ 156 Figure 20: Median FRID map highlighting conifer systems. .................................. 157 Figure 21: Median FRID map highlighting chaparral systems. ............................... 158 Figure 22: Median FRID map highlighting desert systems. .................................... 159 Figure 23: Percent biomass reduction of tree species in management areas. .......... 165 v LIST OF TABLES Table 1: Scenarios modeled in LANDIS-II. .............................................................. 39 Table 2: Management approaches, costs, and fuel reduction for conifer systems. .... 47 Table 3: Management strategies for grasslands. ........................................................ 56 Table 4: Management strategies for riparian systems................................................ 59 Table 5: Management strategies for oak woodlands. ................................................. 63 Table 6: Management strategies for montane conifer systems. ................................. 68 Table 7: Management strategies for chaparral communities. .................................... 72 Table 8: Management strategies for Joshua tree woodlands and Mojavean scrub. ... 75 Table 9: Effects of grazing on species cover and species richness of native grasses, native forbs, invasive grasses and invasive forbs (Stahlheber & D'Antonio 2011). ........................................................................................................................... 110 Table 10: Relationship between five invasives and fire regimes . ............................ 151 Table 11: Fire return intervals used in FRID analysis. ............................................ 154 Table 12: Species parameter values. ........................................................................ 161 Table 13: Ordered difference table for the mean severity of each scenario. ........... 166 Table 14: Ordered difference table comparing average number of fires for all scenarios. ........................................................................................................... 167 Table 15: Ordered Difference tables comparing average fire size for all scenarios. 168 Table 16: Ordered Difference table comparing FRI for all scenarios. .................... 169 vi ACKNOWLEDGMENTS This project would not have been possible without the guidance, expertise and support of others. It is with deep gratitude that we acknowledge the contributions of the following