Trends and Factors in Chaparral Landscape Conversion Alexandra D. Syphard Conservation Biology Institute
Actually….
not that 1889 not exactly
^ ^ ^
^ Southern CA
….it just seems like another world Southern California in 1889
North Hollywood - small town named Toluca, then Lankershim
Southern California in 1889
Santa Ana
Orange County was formed, splitting off from Los Angeles - Orange County Archives Southern California in 1889
Burbank 1889 Cahuenga Pass (Hollywood Freeway) in 1897. Courtesy of USC Digital Library - California Historical Society Collection.
Lots of open space (i.e., chaparral!) for hiking or wandering… …and all the other ecosystem services!
September 24,1889 Santiago Canyon Fire
Sheepherders camp Simultaneous Santa Ana 125 000 ha, 4 days Losses: Sheep, grain, crops, timber 0 fatalities, homes
Image: Los Padres National Forest Keeley and Zedler 2009 114 years later… to 2003 Southern California in 2003
North Hollywood now a neighborhood in LA metropolis Southern California in 2003
Orange County – 3rd most populous
Some open areas left Many exotic herbaceous October 25, 2003 Cedar Fire
110 000 ha Simultaneous Santa Ana > 2000 homes 24 fatalities $120 mil firefighting $3 bil damage
Image: David Hume Kennedy What Happened?! Landscape Change in SoCal . Drivers and consequences . Population & urban growth . Fire and exotic grasses . Projecting future change on plant population persistence . Management considerations
Southern California
. Poster child for population growth “One is repeatedly conscious that this was the ‘land of the big boom’” – Lantis et al. 1963
Los Angeles Metropolitan Area ~ 18.5 million Lots of With Population Comes^ Housing
600000 Housing in South Coast
500000
AreaLowDen
400000 AreaHighDen Hectares 300000
200000
100000 Non-metropolitan counties only
0
Exurban - larger footprint Direct Effect of Land Use Conversion . Habitat loss and fragmentation . 30% intact chaparral . Only ~10% coastal sage scrub, 1% native grasslands remain . Most T&E species in continental US
Rate animal species extinctions in CA 60 Regression Equation: 50 y = 57.6942/(1e (- +(x - 1954.9934)/23.4023))
40
30
20
10
0
Number Number animalspecies 1800 1825 1850 1875 1900 1925 1950 1975 2000 Date -M.F. Allen, U.C. Riverside Indirect Effect: The Role of Fire . Natural ecosystem process . Chaparral - dense, continuous canopy . Six months drought & Santa Ana winds . Large, high-intensity crown part of natural fire regime . Humans cause > 95% Fires More Frequent, Extensive
1960 1999
Proximity to humans; But nonlinear
Fire return interval departure – Current vs. presettlement frequencies (Safford and Van de Water 2014) Syphard et al. 2007, 2009
Ten Largest Fires in CA History
100 yrs
10 yrs
2013 Rim Tuolumne August 256,000 Drought May Exacerbate
Keeley & Zedler 2009
Anomalously long, severe drought Generates flammable dead fuels Facilitates long-distance spot fires w/ winds Climate change (?)
Human Consequences of Fire
. Before ‘the big boom’ - plenty of fire; no losses
1940-1950 Human Consequences . Today: Southern CA loses more homes than any place in US
2000 – 2010: >5K homes, >100 killed/injured, $billions Q: What does fire safety for humans have to do with chaparral ecosystem services?!!
A: A lot, but first… Ecological Consequences of Fire Post-fire recovery of chaparral Obligate seeders Obligate resprouters Facultative seeders Species adapted to fire regime Resilient only to periodic wildfire 30 – 200 + years Sensitive to short intervals < ~ 5 -15 yrs Need time to recover & establish seed bank
Vegetation Type Conversion
. Extirpation opens canopy & allows invasion . Annual grass -> more fire -> positive feedback . May also reduce resprouters (Haidinger & Keeley)
Photos by Anna Jacobsen How Extensive Has It Been? . Europeans introduced grasses & forbs ca. early 1800s . Spread rapidly via disturbances, esp. grazing & burning
Recent discussion . “No evidence for extensive conversion” (Meng et al. 2014; PLoS ONE) . Remote sensing index of plant cover ~ 25 years, paired plots . Possibly different disturbance history, slope, etc. . (Only) 50% sites w/ (some to a lot of) reduction after repeat
But what does this really mean? . Let’s think about it
How Extensive Has It Been? . Substantial grass in the 1930s . Expansion apparent, despite potential uncertainty Does Fire Play a Role?
Strong trend: outweigh map uncertainty? How Fast is Type Conversion?
. (Only) 50% sites w/ (some to a lot of) reduction after repeat . This is consistent w/ gradual, cumulative process . Esp. considering potential uncertainty of approach
Photo: R. Halsey SD County 2012 Map
. Extensive verification . Chap – CSS – grass? Gradual opening
2.5
2.0
1.5
1.0
0.5 Mean Fire Fire Frequency Mean 0.0 The Important Question: How Extensive Could It Be? . Recent large fires across huge portions of landscape . Potentially exacerbated with drought, development
Keeley et al. Why Do We Care?
Chaparral top-ranked habitat, CA rare plants (Keeley 2005) Critical habitat for fauna Loss of watershed function & increased erosion Increased ignition potential – risk to humans Carbon storage: chaparral > grass
Photo: R. Halsey Landscape Conversion - Interactions
Climate (??) Air pollution Policy Etc.
House loss
Grass-fire cycle
Direct habitat loss Indirect habitat loss Native shrublands Interactions in the Future: Plant Species Persistence Under Climate Change in the Context of Multiple Threats Alexandra D. Syphard Helen M. Regan Janet Franklin
Work from 2008 – 2014 Synthesis of results and papers: Franklin et al. 2014 Environmental Conservation Modeling Framework
. Rare & endemic plants, including chaparral . Multiple threats: climate change, urban growth, fire, invasive species . SDMs + Urban Growth Model + Climate + Stochastic population model . Relative impacts and management options? . Different vulnerabilities in PFTs? Obligate Seeder: C . verrucosus
. Habitat loss -> population decline . Fire worse than habitat loss – ALL OS species . Repeat fire also reduced resprouting oak . Simulated management for habitat – no effect if high FF
Conclusions for Chaparral
• Need to consider climate relative to other threats • Frequent fire – single greatest threat to OS • Managing for habitat loss only effective if fire controlled • Fire management might also benefit resprouters Q: What does fire safety for humans have to do with chaparral ecosystem services?!!
A: Management is done for human safety, but could also benefit chaparral
Q: How? The Great Pacific Fire Break ? Traditional Fire Management . Fire suppression & fuel reduction . Increased investment, treatments more extensive . Residential losses getting worse . Ecological impacts & corridors for more grass The Role of Fuel Breaks in Southern CA National Forests
Do not passively stop wind-driven fires But play a role as safe access for firefighters Strategic locations, near communities
• Syphard, Keeley, and Brennan
• Forest Ecology and Management 2011
• International Journal of Wildland Fire 2011
Photo: RW Halsey Window Panes 0.8 Safety: Unburned 0.6 U and M Start at the house Destroyed 0.4 Move out from there 0.2 Proportion of Proportion Strutures 0 Dual Single Roof Material Exterior Construction Material 0.7 0.6 0.5 Unburned 0.6 Unburned 0.4 U and M 0.5 U and M 0.3 Destroyed Destroyed 0.2 0.4 0.1 0.3 0 0.2 Proportion of Proportion Structures
Proportion of Proportion structures 0.1 0 Masonry Metal Other Stucco Wood Defensible Space
. Thin vegetation immediately adjacent to house . More than 30 m (100 ft) – no extra protection . Low housing density most significant predictor
More than 30m – unnecessary Syphard, Brennan & Keeley 2014 ecological impacts Housing Arrangement & Location
! Unburned ! Burned Most likely to burn:
-Low-intermediate density
-Small, isolated cluster
-Close to edge of cluster
-Steep slope
-Fewer roads
Syphard et al. 2011 PLoS ONE Land Use Decision-Making
. Can’t change existing, but would planning for future actually reduce risk? And conserve biodiversity?
. Land planning through zoning . Policies advocating different growth patterns . Directly regulate where houses are placed
. Land acquisition for biodiversity protection . New housing restricted, must go elsewhere . Different priorities, e.g., most area versus biodiversity / fire risk
Planning Simulations via Zoning . Projected fire risk to homes . Habitat area and fragmentation (same rank as risk)
0.050
Current 0.045 Infill Infill Expand 0.040 Leapfrog 0.035
0.030
0.025
Expansion risk landscape Mean Existing 0.020 2010 2015 2020 2025 2030
Syphard et al. PLoS ONE 2013 Leapfrog Land Purchase for Conservation . Different strategies affect fire risk and biodiversity . Purchased in high fire hazard – lowest fire risk and habitat loss
Purchase of high hazard Forces infill near the coast Butsic et al. in prep
Ignition Prevention . Different causes – different spatial and temporal patterns . Influence size and impact of fire
Syphard and Keeley 2015 IJWF
San Diego County Santa Monica Mountains Future Conversion? “If you do not change direction, you may end up where you are heading.” Lao Tzu
?
? Concluding Thoughts . Land use - primary driver of conversion (1889 to now) . Direct loss & fragmentation – primary cause of extinctions . Indirect effects . Human ignitions alter frequency, pattern of fire . Exotic species (esp annual grass) compete & replace . Complex (coupled natural-human) system of interactions and feedbacks . Need to increase our understanding, esp. given climate, etc. . Fire may be single greatest threat some species (OS) . Adaptation to climate may require long fire intervals
Concluding Thoughts . Fuels - one part of larger, science-based ,comprehensive approach . Safety alone: Most cost-effective may be defensible space, construction . Safety AND resources: Land use planning, ignition reduction . Reduces exposure (preventative) and potentially reduces frequency
Land use may have been the source of the conversion; maybe it is the source of our solutions
Coauthors and Contributors
Jon Keeley Tess Brennan Volker Radeloff Avi Bar Massada Robert Taylor Marti Witter Van Butsic Susan Stewart CJ Fotheringham Helen Regan Erin Conlisk Alan and Lorrie Flint Rebecca Swab Toni Mizerek Janet Franklin Tim Bonebrake Clarke Winchell P. Zedler, D. Lawson, MA Hawke Frank Davis Lee Hannah R. Shaw, R. Akcakaya, Kurt Anderson, M. Ikegami David Keith