AGU 2013 TALKS AND POSTERS
TALKS
TITLE: From Restoration to Resilience Ecology: Rapid Ecosystem Shifts are Triggered by Interactions of
Landscape Fire and Climate Change
Donald A Falk1
1.
University of Arizona, Tucson, AZ, United States.
Many studies predict changes in species distributions in response to changing climate. Both modeling and
empirical studies suggest that such changes due to climate alone are likely to be expressed at multi-annual to
decadal time scales. In contrast, severe large- scale disturbances can reorganize ecosystems on much shorter time
scales of days to months. To understand these dynamics, we are studying the impacts of multiple successive fires
and post-fire succession in southwestern North America, which are leaving large areas of landscape with nearly
total tree mortality. We posit that it is the combination of climate change and severe disturbance that is most
likely to trigger abrupt ecosystem transitions into novel configurations, rather than either factor acting separately.
These new configurations can be resilient in their new state, and resistant to return to pre-disturbance
conditions. Such abrupt transitions are predicted to become more common under conditions of altered future
climate and amplified disturbance regimes: climate provides the envelope within which these dynamics occur, but
disturbance provides the trigger for abrupt system reorganization. At larger scales we have compiled the largestever data set for historical fire regimes in western North America to understand how climate variation has
regulated disturbance regimes historically. We explore the implications of rapid ecosystem responses for design
and practice of ecological restoration in a rapidly changing world, and the emergence of resilience ecology as a
new paradigm in the evolution of restoration ecology.
TITLE: Holocene Fire, Climate and Erosion in the Jemez Mountains, New Mexico: Natural and Anthropogenic
Controls
Erin P Fitch1, Grant A Meyer2
1.
Hawai‘i Institute of Geophysics & Planetology, Univ Hawai‘i Mānoa, Honolulu, HI, United States
2.
Earth & Planetary Sciences, Univ New Mexico, Albuquerque, NM, United States
Ponderosa pine and mixed-conifer forests in the Jemez Mountains have been ravaged by extensive severe fires in
the last two decades, which burned almost 1000 km2, roughly 30% of this middle-elevation range. Tree-ring fire
history reconstructions indicate that a low-severity fire regime characterized the ca. 400 years before
Euroamerican settlement, and that fuel buildup from fire suppression and land-use impacts contributed to
increased fire severity in recent years. In order to better understand natural variability, climatic influences, and
erosional effects of wildfire activity since ~5000 cal yr BP, we identified and 14C-dated fire- related alluvial
deposits in the 2002 Lakes Fire area in the southwestern Jemez Mountains. These deposits indicate that most late
Holocene fire-related erosional events were relatively minor, consistent with the low-severity burns that
dominate the tree-ring record, but larger debris flows also occurred, suggesting at least small areas of highseverity fire. Although changes in postfire sedimentation are not so clearly related to millennial-scale Holocene
climatic changes as in the Northern Rocky Mountains, peaks in fire-event probability correspond with severe
regional multidecadal droughts ca. 1800 and 375 cal yr BP. Local microclimatic controls on vegetation, soils, and
post-fire sedimentation are also evident. Relatively dense mixed-conifer stands including Douglas-fir typify
moister north-facing basins, where soils are apparently thicker and more permeable than on southerly aspects.
Alluvial fans of these basins are dominated by fire-related deposits (77% of measured stratigraphic thickness),
thus we interpret that little erosion occurs in the absence of wildfires. Holocene fire-related events from north
slopes are also of somewhat lower frequency, and possibly of higher severity. In contrast, in ponderosa pinedominated south-facing basins, fire-related deposits make up only 39% of measured fan deposits. On drier south
aspects, thin soils, large areas of steep exposed bedrock, and sparser vegetation allow greater runoff and
sediment in the absence of fire, making for a lesser relative importance of fire in erosion. The lack of exposed and
dated deposits older than 5000 cal yr BP, even where fan feeder channels were incised to bedrock in debris-flow
and flood events after the 2002 Lakes Fire, indicates that most stored alluvium was scoured from these channels
in the middle Holocene, possibly from more severe fires and postfire erosion. It also suggests that erosional
response after the Lakes Fire was at least locally greater than at any time in the last 5000 yr, possibly from the
combined influence of fire suppression and recent warming and severe drought. However, expansion of this small
study area would allow a clearer view of fire-climate-erosional linkages in the Jemez Mountains, and the degree
to which modern climatic warming and anthropogenic impacts have heightened severe fire activity.
TITLE: Resilience and sensitivity of high-severity fire regimes to climatic variability from centuries to millennia
Philip E Higuera1, Ryan Kelly2, Fengsheng Hu2
1.
College of Natural Resources, University of Idaho, Moscow, ID, United States.
2.
Plant Biology, University of Illinois, Urbana, IL, United States.
Robust links between climate and wildfire activity at annual timescales suggest that climatic warming will lead to
increases in fire frequency and severity. However, feedbacks and interactions with vegetation, in response to
climate itself and altered fire regimes, will mediate the direct impact of climatic change on wildfire regimes.
Understanding these mechanisms is challenging, particularly in high-severity fire regimes, because their dynamics
evolve over multiple decades to centuries. Retrospective analyses utilizing fire history records offer one of the
best ways to assess fire-regime sensitivity to climatic variability across multiple time scales. We use historical and
paleo records of fire, climate, and vegetation to highlight themes from high-severity fire regimes from western
North America relevant for anticipating fire-regime response to future climate change.
At millennial time scales, paleo records suggest that fire regimes can be particularly sensitive to climate-induced
changes in vegetation. In the absence of large-scale vegetation change, the millennial-scale average rate of
burning in many paleo records is surprisingly resilient to the direct impacts of climatic change. This long-term
resilience is observed in Holocene records from the southern Rocky Mountains north to the Alaskan arctic. At
small spatial and temporal scales, high variability exists and can often be attributed to the direct impacts of
climatic variability on summer moisture deficits, consistent with fire-climate relationships in stand- replacing fire
regimes at annual timescales. Feedbacks among climate, vegetation, and fire are also apparent at these shorter
temporal scales, with vegetation changes limiting or promoting flammable fuels at landscape scales, and
subsequently mediating the links between climate and fire activity. The paleo record supports predictions that
21st-century warming will likely lead to increased burning, but it further suggests that fire-regime response will be
more complicated than expected based on direct, annual-scale fire-climate relationships alone.
TITLE: Does decreased orographic enhancement explain declining annual streamflows and recent increases in
wildfire fire activity in the Pacific Northwestern US?
Zachary A Holden1, Charles Luce2, Penelope Morgan3, Michael Crimmins5, John T Abatzoglou4
1.
Geography, University of Montana, Missoula, MT, United States.
2.
Rocky Mountain Research Station, US Forest Service , Boise, ID, United States.
3.
Forest Rangeland and Fire Sciences, University of Idaho, Moscow, ID, United States.
4.
Geography, University of Idaho, Moscow, ID, United States.
5.
Soil, Water and Environmental Science, University of Arizona, Tucson, AZ, United States.
The influences of changing snowpack on the hydrology of the western US have been well noted, with trends in
snowpack declines, early streamflow timing and associated fire activity attributed primarily to warming
temperatures. We present several lines of evidence suggesting that historical declines in high elevation
precipitation have contributed to early snowmelt timing, reduced annual streamflow, and increased annual area
burned in the Pacific Northwest. Using satellite-derived estimates of area burned and area burned severely, we
show that annual flow, an integrator of basin-wide precipitation, explains three times as much of the variability in
interannual wildfire activity as does the center of timing of annual flow absent the influence of flow variability.
Precipitation and snowpack are fundamentally connected to the timing of snowmelt. Thus, while annual wildfire
area burned is correlated with snowmelt timing, precipitation quantity and distribution provide a more direct
mechanistic explanation of recent wildfire activity in this region. The magnitude of streamflow declines cannot be
explained by either increased evapotranspiration or decreases in precipitation at low elevation weather stations,
implicating declining orographic enhancement as a possible mechanism for the substantial declines in streamflow
observed in recent decades.
TITLE: Frequent, Low-Intensity Fire Increases Tree Defense To Bark Beetles
Sharon Hood1, Anna Sala1
1.
Biological Sciences, University of Montana, Missoula, MT, United States.
Wildfire and bark beetles are the two largest disturbance agents in North American conifer forests and have
interacted for millennia to drive forest composition, structure, and ecological processes. Recent widespread
mortality in western coniferous forests due to bark beetle outbreaks have been attributed in part to increasing
temperatures and drought associated with global climate change. In fire-dependent forests, fire exclusion has also
led to uncharacteristically dense forests which are also thought to be more susceptible to bark beetle outbreaks
due to increased drought stress in individual trees. These mortality events have spurred strong interest in the
interaction of fire and bark beetles in driving forest dynamics under a changing climate. However, a fact that has
not received adequate attention is whether fire exclusion in fire-dependent forests decreases allocation to tree
defense, thereby making contemporary forests more prone to bark beetle outbreaks, regardless of climate and
stand structure. Fire is known to increase constitutive resin production in many tree species, yet the impact of
frequent fire on expression of better defended tree phenotypes has never been examined. We hypothesized that
frequent, low-intensity fire increases tree resistance to bark beetle attack through systemic induced resistance.
Using a combination of sampling in natural stands for which we had long-term fire history data and an
experimental block design of four thinning and burning treatments, we examined the influence of fire and water
stress on tree defense to determine if frequent fire increases tree defense and the degree to which water stress
modulates this response. We used axial resin ducts as the measure of defense, as this is where resin is both stored
and manufactured in Pinaceae. Resin duct production and density has also been shown to be a better indicator of
mortality from bark beetle attacks than tree growth. Resin duct density increased after fire at all sites. In our
experimental study, tree mortality from bark beetles was higher in control and burn-only treatments than in thinonly and thin-and-burn treatments. Our results suggest that frequent fire increases tree defense to bark beetles
and that fire exclusion in forests with low-intensity fire regimes may allow insect outbreaks to occur more easily,
beyond effects due to changes in stand structure alone.
TITLE: Spatiotemporal surface shortwave forcing from fire-induced albedo change in interior Alaska
Shengli Huang1, Shuguang Liu2
1.
2.
USGS EROS Center, Sioux Falls, SD, United States.
USGS EROS, Sioux Falls, SD, United States.
Quantifying the climate impacts of high-latitude fires requires a regional assessment of surface shortwave forcing
(SSF). We applied an image reconstruction approach to depict the spatiotemporal albedo change and SSF from
the 2001-2010 fires in interior Alaska. On the regional perspective, the postfire albedo increased in fall, winter,
and spring; the negative SSF peaked in spring; and the 2005-2010 SSF for the 2004 fire scars was 1.30, -4.40, -3.31,
-4.00, -3.42, and -2.47 Wm-2, which supports previous findings that boreal fires might cool the Earth from a
regional perspective. Our method could reveal spatially explicit pattern in albedo change and SSF. The integrated
annual SSF map showed significant spatial variation with a mean of -3.15 Wm-2 and a standard deviation of 3.26
Wm-2. 16% of the fires that had positive SSF were dominated by prefire deciduous forests and shrubs, which
implied that previous finding of the negative SSF from a single boreal fire was insufficient.
TITLE: Different Climate - Fire Relationships on Forested and Non-Forested Landscapes in California
Jon E. Keeley1, 2
1.
EEB, UCLA, Three Rivers, CA, United States.
2.
Western Ecological Research Center, U.S. Geological Survey, Three Rivers, CA, United States.
Wildfire activity has increased in western USA forests and climate change is considered a driving factor. Previous
studies have shown that over the past several decades forest fires have increased significantly on forested
landscapes and is correlated with warmer and drier conditions. However, the bulk of the landscape in the western
US comprises non-forested ecosystems and there are no reports on trends in fire activity for these landscapes.
Here we show that in the highly fire-prone Sierra Nevada region of California increased fired activity over the last
50 years has only occurred in the higher-elevation forests, and is not characteristic of the lower elevation
grasslands, woodlands and shrublands. In our study, forests exhibited increased fire activity in years with warmer
and drier springs, both in the early twentieth century as well as more recently. On lower elevation non-forested
landscapes warmer and drier conditions were not related to fire activity over the course of the last 90 years of
record. These patterns predict that climate changes including higher spring temperatures and lower spring
precipitation, will have a significant impact on future fire regimes only in higher elevation forested ecosystems.
Future fire regimes in the lower more densely populated landscapes are likely to be more affected by global
changes that directly involve land use patterns and less on climate.
TITLE: Integrating fire with hydrological projections: model evaluation to identify uncertainties and tradeoffs in
model complexity
Maureen Kennedy1, Donald McKenzie2
1.
School of Environmental and Forest Sciences, University of Washington, Seattle, WA, United States.
2.
Pacific Wildland Fire Sciences Lab, USDA Forest Service, Seattle, WA, United States.
It is imperative for resource managers to understand how a changing climate might modify future watershed and
hydrological processes, and such an understanding is incomplete if disturbances such as fire are not integrated
with hydrological projections. Can a robust fire spread model be developed that approximates patterns of fire
spread in response to varying topography wind patterns, and fuel loads and moistures, without requiring
intensive calibration to each new study area or time frame? We assessed the performance of a stochastic model
of fire spread (WMFire), integrated with the Regional Hydro-Ecological Simulation System (RHESSys), for
projecting the effects of climatic change on mountain watersheds. We first use Monte Carlo inference to
determine that the fire spread model is able to replicate the spatial pattern of fire spread for a contemporary
wildfire in Washington State (the Tripod fire), measured by the lacunarity and fractal dimension of the fire. We
then integrate a version of WMFire able to replicate the contemporary wildfire with RHESSys and simulate a New
Mexico watershed over the calibration period of RHESSys (1941-1997). In comparing the fire spread model to a
single contemporary wildfire we found issues in parameter identifiability for several of the nine parameters, due
to model input uncertainty and insensitivity of the mathematical function to certain ranges of the parameter
values. Model input uncertainty is caused by the inherent difficulty in reconstructing fuel loads and fuel moistures
for a fire event after the fire has occurred, as well as by issues in translating variables relevant to hydrological
processes produced by the hydrological model to those known to affect fire spread and fire severity. The first
stage in the model evaluation aided the improvement of the model in both of these regards. In transporting the
model to a new landscape in order to evaluate fire regimes in addition to patterns of fire spread, we find
reasonable outcomes with respect to both. This two-stage model evaluation against multiple criteria and for more
than one landscape demonstrates that a relatively simple model of fire spread can be sufficiently robust to
simulate fire regimes for varying ecosystems and time periods. A careful model evaluation allows for identification
of model uncertainties, which are then reduced by improvements to model structure. When integrating a fire
spread model with a hydrological model for watershed projections it is insufficient to determine the adequacy of
the fire spread module independently of the hydrological model. The integration of the two models should be
assessed as vigorously as the individual modules.
TITLE: Characterizing dichotomous fire regimes of southern California: climate, vegetation and topography
Crystal Kolden1, John T Abatzoglou1
1.
Geography, University of Idaho, Moscow, ID, United States
Southern California Mediterranean ecosystems have long been a subject of wildfire research, in part because of
the extensive Wildland Urban Interface in the region. This mix of homes and vegetation at the edges of wildlands
has resulted in several of the costliest wildfire events in US history due to the number of homes burned, and its
extent is projected to increase significantly over the next 50 years. As such, there has been considerable
investment is identifying fire regime characteristics and potential mitigation measures in the region. However, all
previous wildfire research in the region has initiated from the assumption that the dominant fire regime is
associated with autumn katabatic winds, known locally as Santa Ana winds or Sundowners. To-date, there has
been no effort to determine whether this is an accurate assumption, or whether the fire regime is more complex.
Here, we utilize a dataset of large wildfires (>40ha) from 1948-2010 and a chronology of Santa Ana (SA) wind
occurrence to disaggregate two distinct fire regimes in southwestern California: wildfires associated with SA wind
occurrence events, and those not associated with Santa Ana conditions (NSA) that are fuel- and topographydriven instead. By decomposing burned area into SA and NSA fires, significant differences in seasonal,
biogeographic and topographic characteristics were found, as well as distinct and significantly stronger climatefire relationships than previously reported. NSA area burned was associated with summer fires, peaking in July,
and significantly higher elevation, greater forested area, steeper slopes, and broadly across all aspects. SA area
burned was associated with autumn fires, peaking in October, and significantly lower elevation, greater shrubland
area, lower slopes, and more southeastern aspects. Annual burned area in NSA fires was associated with low
spring precipitation, high vapor pressure deficit and low fuel moistures during the summer months that increase
the seasonal window for fuel flammability. Furthermore, annual burned area in forested lands was correlated to
concurrent long-term drought, whereas annual burned area in shrublands was correlated with pluvial conditions
during the prior growing season. By contrast, annual area burned in SA fires did not show any robust relationship
to climate anomalies in preceding months. Rather, large annual area burned in SA fires was associated with a
delay in the onset of cool season precipitation that enables persistent low fuel moisture into a time of the year
when SA events become more frequent. A significant increase in NSA annual burned area, the number of large
fires in early summer (May- Jul) and the timing of fuel-driven wildfires was observed over the 60-year record,
potentially due to increased early summer vegetation stress in recent decades. Such changes are consistent with
projected climate change for southern California suggesting that NSA wildfires may play a more dominant role in
landscape disturbances and hazards. These findings suggest that previous research aggregating SA and NSA
wildfires may produce considerably different results of these two distinct fire regimes are uncoupled and
addressed individually.
TITLE: The limits of statistical climate-fire modeling: what goes up must come down
Jeremy S Littell1, Donald McKenzie2
1.
Alaska Climate Science Center, USGS, Anchorage, AK, United States.
2.
Pacific Wildland Fire Sciences Laboratory, United States Forest Service, Seattle, WA, United States.
Climate and fire are strongly linked, although the relationship between them is contingent on fuels and thus fire
responses to climate variability and change vary considerably across ecosystems, fuels management, and land
use. By comparing relationships between climate and wildfire in the western U.S., we evaluated the standard
conceptual model of fire response to climate change, which is essentially that increasing temperature will cause
longer fire seasons and increased area burned. However, the observational data indicate that this hypothetical
response is too simple. When considered as a whole across the western U.S., fire climate responses across a
gradient of water balance deficit (potential minus actual evapotranspiration) area burned varies non linearly as a
function of drought, first increasing with increasing deficit but then declining with further increasing deficit. This
result implies that future fire projections based on climate change scenarios must be approached with caution, as
fire cannot be expected to increase indefinitely with deficit. Instead, the relationships between fuel availability
and continuity likely mediate the fire-climate relationship at both local and regional spatial scales. We explore the
consequences of approaching future fire projections as linear responses to climate and present a qualitative
classification of ecosystem proximity to threshold change in fire-climate response.
TITLE: Smokey Bear is Dead: A New Era of Wildfires in the Western U.S.
Jennifer L Pierce1, Jenna Duffin2, Eric Lindquist1, Thomas Wuerzer1, Michael Pellant3
1.
Boise State University, Boise, ID, United States.
2.
Geography, University of Oregon, Eugene, OR, United States.
3.
Great Basin Restoration Initiative Coordinator, Bureau of Land Management, Boise, ID, United States.
High fuel densities, combined with increasingly severe drought, make the western US highly susceptible to
changes in the timing of snowmelt and increases in the length of the fire season. The forests and rangelands of
Idaho are especially prone to wildfire; in 2012, over 1.7 million acres burned across Idaho, more acres than in any
other state. Climate change is projected to increase summer temperatures and decrease summer precipitation in
Idaho, and a drier, warmer, and more variable climate will increase the risk of stand-replacing fires. While
infrastructure and alert systems are in place to warn residents about threats from hurricanes, floods and
tornados, there is limited protection for communities in the ‘fire-plain.’ Part of this lack of preparation may stem
from the belief that fires can be prevented or stopped; a perception that has been perpetuated by ‘Smokey Bear,’
and the generally successful interval of fire suppression during the 1960’s-1980’s. However, in the mid-1980’s,
severe drought, rising temperatures, and early snowmelt have brought an era of ‘mega-fires’ to the American
West. Periods of recurring high wildfire activity across the western US are not unprecedented in the paleo-record,
but the frequency of large fires (> 400 ha) and the annual area burned have increased in the modern. For
example, in the past 10 years in Idaho, 17 fires burned over 100,000 acres each: six of those fires occurred in
2012. Likewise, the size and severity of rangeland fires in the Western U.S. has increased by almost an order of
magnitude in recent decades; in the early 1980’s, range fire extents over 100,000 acres was unheard of, but has
become increasingly common in recent years (Pellant, 2013). Boise State University’s departments of Geoscience,
Community and Regional Planning, and the Public Policy Center are examining the risks and impacts of fire along
the Boise WUI. The research integrates the perspectives of the geosciences and social sciences by combining
physically-based fire hazards, effective fire management policies, and planning in the West.
TITLE: Using ecological forecasting of future vegetation transition and fire frequency change in the Sierra
Nevada to assess fire management strategies
James H Thorne1, Mark W Schwartz1, Andrew J Holguin1, Max Moritz2, Enric Batllori2, Karen Folger3, Koren Nydick3
1.
University of California, Davis, CA, United States.
2.
Environmental Science Policy and Management, University of California, Berkeley, CA, United States.
3.
Sequoia and Kings Canyon, National Park Service, Ash Mountain, CA, United States.
Ecological systems may respond in complex manners as climate change progresses. Among the responses, sitelevel climate conditions may cause a shift in vegetation due to the physiological tolerances of plant species, and
the fire return interval may change. Natural resource managers challenged with maintaining ecosystem health
need a way to forecast how these processes may affect every location, in order to determine appropriate
management actions and prioritize locations for interventions. We integrated climate change- driven vegetation
type transitions with projected change in fire frequency for 45,203 km2 of the southern Sierra Nevada, California,
containing over 10 land management agencies as well as private lands. This Magnitude of Change (MOC)
approach involves classing vegetation types in current time according to their climate envelopes, and identifying
which sites will in the future have climates beyond what that vegetation currently occurs in. Independently, fire
models are used to determine the change in fire frequency for each site. We examined 82 vegetation types with
>50 grid cell occurrences. We found iconic resources such as the giant sequoia, lower slope oak woodlands, and
high elevation conifer forests are projected as highly vulnerable by models that project a warmer drier future, but
not as much by models that project a warmer future that is not drier than current conditions. Further, there were
strongly divergent vulnerabilities of these forest types across land ownership (National Parks versus US Forest
Service lands), and by GCM. For example, of 50 giant sequoia (Sequoiadendron giganteum) groves and complexes,
all but 3 (on Sierra National Forest) were in the 2 highest levels of risk of climate and fire under the GFDL A2
projection, while 15 groves with low-to-moderate risk were found on both the National Parks and National
Forests 18 in the 2 under PCM A2. Landscape projections of potential MOC suggest that the region is likely to
experience strong upslope shifting of open grassland, chaparral and hardwood types, which may be initiated by
increased fire frequencies, particularly where fires have not recently burned within normal fire recurrence
interval departures (FRID). An evaluation of four fire management strategies (business as usual; resist change;
foster orderly change; protect vital resources) across four combinations of future climate and fire frequency
found that no single management strategy was uniformly successful in protecting critical resources across the
range of future conditions examined. This limitation is somewhat driven by current management constraints on
the amount of management available to resource managers, which suggests management will need to use a
triage approach to application of proactive fire management strategies, wherein MOC landscape projections can
be used in decision support.
TITLE: Varying likelihood of Megafire across space and time in the western contiguous United States
E. Natasha Stavros1, John T Abatzoglou2, Narasimhan K Larkin3, Donald McKenzie3, E. Ashley Steel3
1.
Jet Propulsion Laboratory, Pasadena, CA, United States.
Geography, University of Idaho, Moscow, ID, United States.
3.
Pacific Wildland Fire Science Lab, US Forest Service, Seattle, WA, United States.
2.
Studies project that a warming climate will likely increase wildfire activity. These analyses, however, are of
aggregate statistics of annual area burned and to anticipate future events, especially those of particular concern
like megafires, we need more fire specific projections. Megafires account for a disproportionate amount of
damage and are defined quantitatively here as fires that burn >20,234 ha ~50,000 ac. Megafires account for the
top two percent of all fires and represent 33% of all area burned in the western contiguous United States from
1984 to 2010. Multiple megafires often occur in one region during a single fire season, suggesting that regional
climate is a driver. Therefore, we used composite records of climate and fire to investigate the special and
temporal variability of the megafire climate space. We then developed logistic regression models to predict the
probability that a megafire will occur in a given week. Accuracy was good (AUC > 0.80) for all models. These
analyses provide a coarse-scale assessment for operationally defined regions of megafire risk, which can be
projected to determine how the likelihood of megafire varies across space and time using the Intergovernmental
Panel on Climate Change representative concentration pathways (RCPs) 4.5 and 8.5. In general, with the
exception of Northern California (NCAL), Southern California, and the Western Great Basin, there is increasing
proportional change over time in the probability of a megafire. There was a significant (p≤0.05) difference
between the historical modeled ensemble mean probability of a megafire occurrence from 1979 to 2010 and both
RCP 4.5 and 8.5 means during 2031 to 2060. Generally, with the exception of the Southwest and NCAL, there are
higher probabilities of megafire occurrence more frequently and for longer periods both throughout the fire
season and from year to year, with more pronounced patterns under RCP 8.5 than RCP 4.5. Our results provide a
quantitative foundation for investigating and developing management strategies to mitigate the effects of
megafires.
TITLE: A tree-ring based reconstruction of North Pacific Jet variability and its influence on Sierra Nevada fire
regimes
Valerie Trouet1, Flurin Babst1, Julio L Betancourt2
1.
Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ, United States.
2.
USGS, Reston, VA, United States.
Over the last decade, the northern hemisphere polar jet stream – the fast- flowing, high-altitude westerly air
current that flows over mid and northern latitudes - has experienced a more meridional (north-south) and slower
wave progression. This anomalous behavior contributed to extreme mid-latitude weather events across the globe,
including drought and forest fires in the American Southwest (2012), summer heatwaves in Russia (2010), and
floods in central and western Europe (2007). The position of the North Pacific Jet (NPJ) strongly modulates winter
hydroclimatology in the Sierra Nevada and the Central Rocky Mountains; moreover, a persistent southerly
(northerly) trajectory can offset (reinforce) losses in regional snowpack predicted with greenhouse warming .
Snowpack variability has a fundamental impact on water resources and ecosystem disturbances. An increase in
wildfire activity in the American West since the mid-1980s, for instance, has been related to decreasing
snowpacks and earlier and faster snowmelt. Recent anomalous, high-amplitude, jet stream fluctuations are
consistent with model projections forced by greenhouse gases. By weakening the pole-equator temperature
gradient, enhanced Arctic warming in particular may cause the jet to slow and extreme weather patterns (e.g.,
blocking high pressure cells) to persist. Questions exist about the ability of climate models to simulate jet stream
dynamics, however, and the instrumental record is still too short to fully evaluate the natural range of jet stream
variability. We developed a reconstruction of winter NPJ variability from tree-ring data at two locations where
climate is strongly influenced by the latitudinal NPJ position. We combined Blue Oak (Quercus douglasii) data
from central California with climate-sensitive tree-ring series from multiple species in the northern Rockies in a
nested PCA model that explained up to 41% of the variance in the instrumental NPJ target. The resulting
reconstruction (1409-1990) demonstrates interannual to decadal-scale variability in the latitudinal position of the
winter NPJ, and shows that its southern diplacement in recent decades (1991-2010) is unusual for the last 600
years. Furthermore, we found a strong relationship between reconstructed NPJ position and historical (17001850) fire activity in the Sierra Nevada, with increased (decreased) fire activity occurring after winters with an
anomalously northerly (southerly) NPJ position. This relationship between winter climate and the normal fire
season (July to October) is linked to the seasonal snowpack amounts and the timing of snowmelt and leafout, and
is important in the prediction of problematic fire seasons
TITLE: Can climate change increase fire severity independent of fire intensity?
Phillip van Mantgem1, Jonathan Nesmith2, MaryBeth Keifer3, Eric Knapp4, Alan L Flint5, Lorraine E Flint5
1.
Redwood Field Station, USGS, Arcata, CA, United States.
2.
Sierra Nevada Network Inventory & Monitoring Program, National Park Service, Three Rivers, CA, United States.
3.
National Interagency Fire Center, National Park Service, Three Rivers, CA, United States.
4.
Pacific Southwest Research Station, U.S. Forest Service, Redding, CA, United States.
5.
California Water Science Center, U.S. Geological Survey, Sacramento, CA, United States.
There is a growing realization that regional warming may be linked to increasing fire size and frequency in forests
of the western US, a trend occurring in concert with increased fuel loads in forests that historically experienced
frequent surface fires. Recent studies have also suggested that warming temperatures are correlated with
increased fire severity (post-fire tree mortality). The mechanism whereby fire severity might increase in response
to warming is presumed to be increasing probabilities of hazardous fire weather (higher air temperature, lower
relative humidity and fuel moisture). While likely true, this view does not consider the biological context of the
fire event. Here we present evidence that trees subject to environmental stress are more sensitive to subsequent
fire damage. Tree growth records, used as an index of health for individuals, show that for two tree species (Abies
concolor and Pinus lambertiana) in the Sierra Nevada of California poor growth leads to increased probabilities of
mortality following fire. Plot-based fire monitoring databases from over 300 sites across the western US
demonstrate that indices of drought stress are strongly predictive of post-fire tree survivorship. In sum, these
results suggest that recent climatic trends may lead to a de facto increase in fire severity, even when there is no
change in fire intensity.
TITLE: A multi-scale conceptual model of fire and disease interactions in North American forests
J Morgan Varner1, Jesse K Kreye1, Rosemary Sherriff2, Margaret Metz3
1.
Forestry, Mississippi State University, Miss State, MS, United States.
2.
Geography, Humboldt State University, Arcata, CA, United States.
3.
Plant Pathology, University of California- Davis, Davis, CA, United States.
One aspect of global change with increasing attention is the interactions between irruptive pests and diseases and
wildland fire behavior and effects. These pests and diseases affect fire behavior and effects in spatially and
temporally complex ways. Models of fire and pathogen interactions have been constructed for individual pests or
diseases, but to date, no synthesis of this complexity has been attempted. Here we synthesize North American
fire-pathogen interactions into syndromes with similarities in spatial extent and temporal duration. We base our
models on fire interactions with three examples: sudden oak death (caused by the pathogen Phytopthora
ramorum) and the native tree tanoak (Notholithocarpus densiflorus); mountain pine beetle (Dendroctonus
ponderosae) and western Pinus spp.; and hemlock woolly adelgid (Adelges tsugae) on Tsuga spp. We evaluate
each across spatial (severity of attack from branch to landscape scale) and temporal scales (from attack to
decades after) and link each change to its coincident effects on fuels and potential fire behavior. These syndromes
differ in their spatial and temporal severity, differentially affecting windows of increased or decreased community
flammability. We evaluate these models with two examples: the recently emergent ambrosia beetle-vectored
laurel wilt (caused by the pathogen Raffaelea lauricola) in native members of the Lauraceae and the early 20th
century chestnut blight (caused by the pathogen Cryphonectria parasitica) that led to the decline of American
chestnut (Castanea dentata). Some changes (e.g., reduced foliar moisture content) have short-term
consequences for potential fire behavior while others (functional extirpation) have more complex indirect effects
on community flammability. As non-native emergent diseases and pests continue, synthetic models that aid in
prediction of fire behavior and effects will enable the research and community to prioritize mitigation efforts to
realized effects.
POSTERS
TITLE: Modeling wildfire and hydrologic response to global climate change using the Landlab modeling
environment
Jordan Marie Adams1, Nicole M Gasparini1, Gregory E Tucker2, Erkan Istanbulluoglu3, Eric Hutton4, Daniel E. J.
Hobley2, Sai Siddhartha Nudurupati3
1.
Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, United States.
2.
CIRES and Department of Geological Sciences, University of Colorado, Boulder, CO, United States.
3.
Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, United States.
4.
Commununity Surface Dynamics Modeling System (CSDMS), University of Colorado, Boulder, CO, United States.
Climate change presents new challenges in modeling surface processes across landscapes that are prone to
wildfire. Historical recurrence intervals of wildfire and precipitation must be adapted to account for changes in
climate. Warming temperatures have already been linked to shorter winters, smaller volumes of snowmelt, and
lower soil moisture content, all of which can contribute to more frequent fires. As fire and precipitation
distributions change, the magnitude of fluvial erosion in burned landscapes may change dramatically. Fluvial
erosion driven by large precipitation events post-fire can threaten property, infrastructure and human
life in the short-term, and potentially impact long-term landscape evolution. Understanding postfire landscape response across multiple time scales can be accomplished through numerical modeling of fire and
rainfall events and the resulting stream flow across a landscape. This study uses the Landlab modeling
environment to explore possible fire and precipitation scenarios that could lead to significant post-fire landscape
change. Landlab is a plug-and-play model that is designed to be highly flexible in order to address a wide range of
scientific questions. This study links together a stochastic fire generator, stochastic storm generator, and overland
flow module to explore scenarios that may cause significant flow in the one-year period following a high- severity
fire. Post-fire landscapes have been observed to be particularly vulnerable to fluvial erosion during this period.
The parameters in the fire and rainfall generator are varied to test whether erosion-inducing precipitation events
will increase in frequency and severity as climate changes. We analyze potential scenarios in which fire and storm
recurrence change with the climate. Three test cases are explored: increasing fire recurrence while holding the
parameters of the precipitation distribution constant; increasing the recurrence of precipitation events while
holding the fire recurrence parameter constant; and increasing both event frequencies. In all cases, we explore
the number of times in a 100-year period that flow events large enough to cause significant fluvial erosion occur
in the critical one-year post-fire period. We test the scenarios on the topography of the Spring Creek watershed,
which experienced significant erosion following the 1996 Buffalo Creek fire.
TITLE: Holocene disturbance dynamics from a pine-dominated forest in central British Columbia, Canada
Kendrick J Brown1, 2, Nicholas Hebda1, Nicholas Condor1, Richard Hebda2, Brad Hawkes1
1.
Canadian Forest Service, Victoria, BC, Canada.
2.
Royal British Columbia Museum, Victoria, BC, Canada.
A lake sediment record was retrieved from the Sub-Boreal Pine-Spruce biogeoclimatic zone on the Chilcotin
Plateau in central British Columbia, Canada. The record is being analyzed for charcoal, pollen, and magnetic
susceptibility, as well as insect and mollusc content. The oldest radiocarbon age is 9.2 cal BP, illustrating that the
record spans most of the Holocene. Regarding fire disturbance, charcoal fragments are persistent throughout the
core, revealing that fire disturbance has characterized the site for millennia. In total, 74 fire events were
recognized. During the warm dry early Holocene, fire frequency was 12-15 fires 2000 yr-1 and peak magnitudes
were low, possibly in response to a more open landscape. A change in fire regime occurred at ca. 5000 cal BP, as
fire frequency increased, peaking at ca. 20 fires 2000 yr-1 by 3000 cal BP. Peak magnitude likewise increased
notably, possibly in response to the development of denser forest cover. On-going analysis of pollen will better
constrain the vegetation history in this poorly sampled region. In contrast to charcoal, which was pervasive,
Dendroctonus ponderosae (mountain pine beetle) remains were absent in both modern and paleo samples.
Given that several insect outbreaks have occurred in the region in the last 100 years, the scarcity of remains is
likely related to taphonomic issues.
TITLE: Regional Trends in Large Wildfires and Climate in the Western U.S., 1984-2010
Philip E Dennison1, Simon Brewer1, James Arnold1, Max Moritz2
1.
Department of Geography, University of Utah, Salt Lake City, UT, United States.
2.
Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, United States.
The Monitoring Trends in Burn Severity (MTBS) database provides remote sensing- based maps of fire perimeters
for all fires larger than 405 ha (1000 acres) in the Western U.S. The database uniquely permits analysis of large
fires on all lands, collected using a uniform methodology, for the 1984-2010 period. We used MTBS data to
examine changes in the annual number of large fires, total area burned in large fires, large fire size, and day of
year of ignition (DOY) for ten ecoregions across the Western U.S. Fire trends were compared to seasonal trends in
maximum temperature, precipitation, and Self-Calibrated Palmer Drought Severity Index (SCPDSI) derived from
monthly PRISM data. In a majority of ecoregions, our analysis revealed statistically significant positive trends in
the number of large fires and/or total area burned in large fires per year. When all regions were combined, fire
occurrence increased at a rate of six large fires per year and total area burned increased at a rate of 274 km2 per
year over the 1984-2010 period. Multiple ecoregions demonstrated significant increases in the 90th percentile of
large fire size, with trends as high as +3 km2 per year. The 10th percentile of DOY, an indicator of early season
large fires, declined in two high elevation ecoregions. This finding agrees with previous research that has
observed correlations between earlier snowmelt and increased fire activity at high elevation. Fall maximum
temperature trended warmer and SCPDI in all seasons trended drier in the ecoregions with strongest increases in
fire activity. At the Western U.S. scale, increases in large fire occurrence and total area burned coincide with
increased drought severity over the 1984-2010 period.
TITLE: Modeling the Spatial Pattern of Wildfire Ignition and Burned Area in Southern Californian Mediterranean
Ecosystems
Nicolas Faivre1, Yufang Jin1, Michael Goulden1, James Tremper Randerson1
1.
University of California Irvine, Irvine, CA, United States.
Wildfire ignition requires a combination of an ignition source and suitable weather and fuel conditions. Models of
fire occurrence and burned area provide a good understanding of the physical and climatic factors that constrain
and promote fire spread and recurrence, but information on how humans influence ignition patterns and burned
area is still lacking at a scale compatible with integrated fire management. We first investigated the relative
importance of the physical, climatic, and human factors regulating ignition probability across Southern California.
A 30-year exploratory analysis of one-way relationships indicated that distance to roads, distance to housing, and
topographic slope were the major determinants of ignition occurrence and frequency. A logistic regression model
explained 70% of spatial variability in ignition occurrence (presence or absence of an ignition in each 3 km grid
cell) whereas a Poisson-type regression model explained 45% of the spatial variability in ignition frequency in
national forests across Southern California. Predicted ignition probability was a key indicator of the spatial
variability of burned area, explaining approximately 9% of the variance for Santa Ana fires and 21% of the
variance for non-Santa Ana fires across Southern California.
In a second step we combined the previous ignition modeling framework with other data sources to model the
spatial distribution of burned area. Preliminary results showed that average wind speed alone explained
approximately 30% of the spatial variation in burned area from Santa Ana fires. Further integration of the effects
of fuel continuity, moisture, and accumulation and their interaction with wind speed and direction improved our
spatial assessment of burned area risk in Southern California. Our results may have implications for strategic fire
management in the region.
TITLE: Controls over nitrogen cycling in California chaparral
Erin J Hanan1, Joshua Schimel1
1.
University of California SB, Santa Barbara, CA, United States.
Chaparral landscapes of southern California and other Mediterranean-type ecosystems are structured by fire.
They exist in environments that typically do not receive rain for 6 months or more at a time, making combustion
inevitable. The heavy winter rains following fire can erode soil and leach nutrients such as nitrogen into streams
and reservoirs, particularly along slopes that have been denuded. The extent to which nitrogen is cycled and
redistributed following fire is a function of the rate at which soil microbes metabolize nitrogen into mobile forms
such as nitrate. However, the specific mechanisms controlling nitrogen metabolism in chaparral are not fully
understood. We measured mineralization and nitrification rates in ecosystems dominated by species typical of
southern and central California chaparral, and conducted a laboratory incubation to experimentally examine the
influence of pH, charcoal, and ammonium supply on nitrogen dynamics. Nitrate production was significantly
enhanced in recently burned chaparral, which correlated with elevated soil pH. Enhanced pH can both raise the
solubility of soil organic matter, and stimulate nitrification, while fires simultaneously release nitrifying bacteria
from competition with vegetation for ammonium. To further explore these processes, we applied ammonium,
pH, and charcoal treatments to samples from 4 chaparral stands, which burned 1, 4, 20 and 40 years ago, using a
factorial design. Treated soils were incubated in mason jars at 50% water holding capacity for 8 weeks. Soil
respiration, substrate induced respiration, mineralization, nitrification, and nitrification potential were measured
periodically to evaluate whether ammonium addition, pH and the presence of charcoal influence substrate
production and nitrification. The threat nitrate of leaching following fire grows with climate change, because fire
and precipitation regimes are expected to become both increasingly variable and punctuated by more intense
events. This work will enhance our mechanistic understanding of how chaparral soils respond to fire, allowing us
to better predict the rates at which they will supply nutrients to watersheds in a changing climate.
TITLE: Wildfires in southern California: climatic drivers and future projections
Yufang Jin1, James Tremper Randerson1, Scott B Capps2, Alexander D Hall2, Nicolas Faivre1, Michael Goulden1
1.
Department of Earth System Science, Univ of California, Irvine, CA, United States.
2.
Department of Atmospheric and Oceanic Sciences, UCLA, Los Angeles, CA, United States.
Southern California experiences different types of fires, including large wind-driven fires that typically occur
during fall Santa Ana events and other fires that occur during the hot and dry Mediterranean summer. Both types
of fires contribute significantly to annual burned area and to
regional fire-induced economic losses. An improved understanding of fire-climate relations is needed for
predicting how these fires are going to change in the future and for better fire management. We developed
statistical models to quantify the impacts of climate on monthly Santa Ana and non-Santa Ana fires using a 51year dataset of fire perimeters and climate variables including Santa Ana frequency and duration, air
temperature, wind speed, relative humidity, and precipitation. For Santa Ana fires, climate variables explained
approximately 58% of the seasonal and interannual variability in the number of fires,
31% of the variability in fire size, and 57% of the variability in burned area. For non-Santa Ana fires,
climate explained 36%, 17%, and 22%, respectively, of the same fire variables. The number of Santa Ana fires
increased during years when humidity during Santa Ana events and fall precipitation were below average,
indicating that weather-driven changes in fuel moisture were a key controller of fire events. In contrast,
cumulative precipitation from the previous 3 winters regulated the number of summer fires significantly,
probably by increasing fine fuel density and fuel connectivity between infrastructure and interior shrublands.
Relative humidity and current year precipitation prior to fire season influenced summer fire size. To predict future
fires, the fire-climate models were then driven by the dynamically down-scaled climate projections from 5 climate
models for the representative concentration pathway 8.5 (RCP8.5). We found that burned area is likely to
significantly increase by the mid-21st century for non-Santa Ana fires, mostly due to increases in fire size. This
finding is consistent with the increasing trend in burned area for non-Santa Ana fires observed over the past 5
decades. The change in burned area for Santa Ana fires was less significant and robust due to the counteracting
effects of decreasing Santa Ana frequency and increasing Santa Ana intensity. Our results suggest that studies
investigating climate change impacts on regional burned area need to separately consider the different fuel and
fire weather controls for Santa Ana and non-Santa Ana fires.
TITLE: Predicting high severity fire occurrence and area burned in a changing climate for three regions in the
Western US.
Alisa Keyser1, Anthony Leroy Westerling1, Jeanne Milostan1
1.
Sierra Nevada Research Institute, University of California Merced, Merced, CA, United States.
A long history of fire suppression in the western United States has interrupted the fire regimes of many forest
types. This interruption has significantly changed forest structure and ecological function and led to increasingly
uncharacteristic fires in terms of size and severity. Research has shown that climate variability drives the
occurrence of large fires and is important to predicting fire severity. We found that Western US area burned in
high severity fire can be accurately predicted using a generalized Pareto distribution model with covariates of
climate, weather, topography, and vegetation. Our model was robust in all but the most extreme fire years, e.g.
1988, 2000, 2002, and 2003, where area burned in high severity was significantly greater than in other years.
We modeled the Northern Rocky Mountains, the Sierra Nevada Mountains, and the Southwestern US to
determine if regional differences in controls on severity were at play in extreme years. The regional analysis
improved model performance by capturing extreme fire years and identified regionally unique covariates. For the
Northern Rocky Mountains the addition of elevation and fire regime condition class improved the prediction in
extreme years. In the Southwest relative humidity and moisture deficit in the month of fire and total fire size
were critical to capturing extreme fire years. The Sierra Nevada model had the most complex set of covariates
that included: vegetation, moisture deficit, evapotranspiration, precipitation, and fire regime condition class. By
incorporating regionally specific variables, our models were robust in prediction of high severity area burned in all
years. For this work, we will apply high and low CO2 emission scenarios from three general circulation models to
our regional statistical models to predict probability of high severity fire occurrence as well as area burned in high
severity for the period 1950-2099. We used the downscaled climate as an input into the VIC hydrologic model to
generate independent variable sets for each future scenario. The modeling output will allow us to identify
potential changes in the annual area burned with high severity fire under future climate as well as areas where
the probable occurrence of high severity fires might increase.
TITLE: Climate change and wildfire around southern Africa
Keiji Kimura1
1.
Hokkaido Univ, Sapporo, Japan.
When the climate change in southern Africa is analyzed, the effects of rainfall by Inter Tropical Convergence
Zone(ITCZ) and cyclone are important. In this study, the rainfall patterns are analyzed with synoptic analysis. The
southern limit of ITCZ is around the arid zone around Namibia, Botswana, Zimbabwe and Mozambique. This zone
has some effects of both ITCZ and extratropical cyclones by season. As well as this, the eastern part of this area
has heavy rainfall by the cyclone from the Indian Ocean once in several years. In the other hand, a lot of wildfire
occurs in this area. The main cause of the wildfire is anthropogenic misbehavior of the fire by the slash-and-burn
agriculture. Recently we can find the wildfire detected with the satellite imagery like Terra/Aqua MODIS. We can
compare the weather environment and the wildfire occurrence with Geographical Information System. We have
tried making the fire weather index suitable for the southern African semi-arid area.
TITLE: Relation between wind speed and burned area on global scale
Gitta Lasslop1, Silvia Kloster1
1.
Max Planck Institute for Meteorology, Hamburg, Germany.
Global datasets of burned area have been analyzed with respect to different fire drivers. Various studies find, that
climatic variables as well as the vegetation composition or the human influence shape the global distribution of
burned area. Wind speed datasets have not been included so far in such analysis. Local studies show that wind
speed influences the rate of spread and also that the rate of spread can decrease for high wind speeds. The
commonly used Rothermel equations suggest a rate of spread which does not further increase when reaching a
certain wind limit. Including fire in global models is a relatively new field and analysis of recent global datasets an
important source of information for improvement of global scale fire models. Fire is a climate driven and climate
relevant process, therefore a realistic response of the modeled fire occurrence with respect to climate variables is
crucial. We analyze the correlation between remotely sensed burned area and three global wind speed datasets
on different spatial and temporal scales, as well as different land cover types. We find that the burned area peaks
for mean wind speeds of about 2 ms-1. Using generalized additive models (GAMs) we analyze the response
functions including other important drivers of burned area, e.g. temperature, net primary productivity,
precipitation, tree cover and population density. Accounting for these other drivers the response functions
confirm increasing burned area with increasing wind speed up to a certain threshold and decreasing burned area
thereafter. We used this information in the global land surface model JSBACH that includes a prognostic fire
model (SPITFIRE) which is based on the Rothermel fire spread equations. The SPITFIRE model did not include the
wind limitation before and model residuals for the burned area compared to present day observations showed a
correlation with wind speed. Including the relationship between wind speed and burned area as derived from the
observations improved the spatial patterns of modeled burned fraction on global scale.
TITLE: Historic Response of Forests to Disturbance; Hydrologic Implications
Millar, Connie 1
1.
USDA Forest Service, Pacific SW Research Station, California, United States
Mountain hydrology is influenced by the composition, structure, and function of forests, which in turn are
affected by patterns and types of disturbance, both ecological (insect, disease) and physical (fire, wind,
avalanche/landslide, weather/climate). Paleo-historic data provide inferences about the natural roles of
disturbance in governing forest condition at landscape scale (e.g., forest die-offs, widespread changes in
composition, forest type, or structure), and offer insights for vegetation and hydrological management under
conditions of current and future climate change. Millennial (Holocene), centennial, and decadal temporal scales
are presented for analysis of forest responses in mountains of western North America. Examples focus on the
long-term effects of short-term disturbance, beneficial effects of disturbance on forest health, importance of
legacy (sequencing of events), pace of climate variability, topographic control on forest health, lag effects, and
interactions of multiple stressors. Historic forest condition and hydrologic relations inferred through
dendrochronological analysis are put into current context.
TITLE: Impacts of snow water equivalent on forest disturbance in the Sierra Nevada with climate change
Andrew Nguyen1, 2, Chase Mueller1, 3, Roy Petrakis1, 4, Spencer Adkins1, 5, Olivia Kuss1, 6, Monica Kumaran1, 7,
Marc Meyer8, Cindy Schmidt1, 9
1.
NASA DEVELOP, Moffett Field, CA, United States.
2.
San Jose State University, San Jose, CA, United States.
3.
University of Texas at San Antonio, San Antonio, TX, United States.
4.
University of Arizona, Tuscan, AZ, United States.
5.
Brigham Young University, Provo, UT, United States.
6.
Indiana University-Purdue University of Indianapolis, Indianapolis, IN, United States.
7.
Harker High School, San Jose, CA, United States.
8.
USDA Forest Service, Pacific Southwest Region, Clovis, CA, United States.
9.
Bay Area Environmental Research Institute, Moffett Field, CA, United States.
High Sierra snow and ice provide the primary water supply for the Sierra Nevada ecosystem. Understanding how
climate change affects high Sierra snowmelt and how these changes impact forest disturbance is important for
future forest management. Snow water equivalent (SWE) anomalies were averaged on a monthly basis and
overall trends of snowpack availability and timing of snowmelt were examined throughout the Sierra Nevada
from 2003 - 2012. Periods of decreased snowpack were examined alongside periods of decreased soil moisture,
increased soil temperature, and increased wild fires. This project used NASA Earth Observations (EOS) such as the
Moderate Resolution Imaging Spectroradiometer (MODIS) for snow cover and Landsat 5 for extent of forest
disturbance and vegetative analysis. We also used ancillary and modeled datasets such as temperature,
precipitation, and water flow rate to provide a better understanding of the relation between snowpack, soil
moisture availability, and soil temperature to wildfires. A Generalized Additive Model (GAM) was used to make
predictions of future forest disturbance patterns as well to analyze the sensitivity of particular variables indicative
of wildfire. This information is useful for forest management decisions within the US Forest Service and will assist
in the incorporation of climate change impact assessments on forest health. http://develop.larc.nasa.gov/
TITLE: A framework for tracking post-wildfire trajectories and desired future conditions using NDVI time series
Steven P Norman1, William Walter Hargrove1, Danny C Lee1., Joseph Spruce2
Eastern Threat Center, USDA Forest Service, Asheville, NC, United States.
2.
Computer Sciences Corporation, NASA Applied Science and Technology Project Office, Stennis Space Center,
MS, United States.
1.
Wildfires could provide a cost-effective means to maintain or restore
some aspects of fire-adapted landscapes. Yet with the added influence of climate change and invasives, wildfires
may also facilitate or accelerate undesired type conversions. As megafires are becoming increasingly common
across portions of the US West, managers require a framework for long-term monitoring that integrates the
trajectories of fire- prone landscapes and objectives, not just conditions immediately after a burn. Systematic use
of satellite data provides an efficient cross-jurisdictional solution to this problem. Since 2000, MODIS-technology
has provided high frequency, 240m resolution observations of Earth. Using this data stream, the ForWarn system,
developed through a partnership of the US Forest Service, NASA-Stennis and others, provides 46 estimates of the
Normalized Difference Vegetation Index (NDVI) per year for the conterminous US. From this time series, a variety
of secondary metrics have been derived including median annual NDVI, amplitude, and phenological spikiness.
Each is both a fire and recovery sensitive measure that allows managers to systematically track conditions with
respect to either the pre-fire baseline or desired future conditions more adaptively. In dry interior forests where
wildfires could be used to thin stands, recovery to untreated conditions may not be desired given fuels objectives
or climate change. In more mesic systems, fire effects may be monitored as staged succession. With both coarse
filter monitoring and desired conditions in hand, managers can better recognize and prioritize problems in
disturbance- prone landscapes. http://forwarn.forestthreats.org/
TITLE: Stream Water and Soil Water Chemistry Following the Table Mountain Wildfire, Washington
Vincent Joseph Roccanova1, Carey Alice Gazis1
1.
Geological Sciences Department, Central Washington University, Ellensburg, WA, United States.
Severe wildfire occurrence in the Western United States increased throughout the 20th century and has
continued to increase into the 21st century. Global climate change resulting from natural and anthropogenic
sources is considered a contributor to this increase in wildfire severity. Fire suppression techniques developed in
the early 20th century are also a factor in increased severe wildfire occurrence as they augment available fuel
loads. Biomass burning releases nutrients that are held within trees and plants. Nitrogen, phosphorous, and
calcium levels have been documented as increasing in stream waters as a result of wildfire. As severe wildfire
occurrence increases, so does the likelihood that stream, and to a lesser extent groundwater, will be loaded with
nutrients and sediments as a result of wildfire activity. Increased nutrient loads can cause algal blooms that
deplete streams of oxygen, important to aquatic plants and animals that reside in these streams. These changes
in water quality can also affect humans who depend on these streams for irrigation and drinking water purposes.
The Table Mountain wildfire in Washington State was started by a lightning strike that occurred at approximately
8:00 PM on Saturday September 8th, 2012. The fire burned for approximately one month and was declared to be
100% contained on Friday October 5th, 2012. Over this period the fire burned a total of 171 square kilometers of
forest. In this study multiple stream and soil water samples were collected from three types of area in the winter
through summer following the fire: severely burned, moderately burned, and unburned. All areas sampled have
similar bedrock and vegetation cover. These samples were analyzed for major ions and trace element
concentrations. Select samples will also be analyzed for strontium isotope ratios. The results of these geochemical
analyses will be presented. Because calcium and strontium have similar properties, their concentrations can be
combined with strontium isotope ratios and used to track the movement of calcium and thus better describe
wildfire effects on calcium cycling.
TITLE: Influence of Antecedent Precipitation on MODIS Active Fire and Fire Radiative Power Retrievals in the
Brazilian Tropical Moist Forest Biome
Sanath Kumar Sathyachandran1, David P Roy1
1.
Geospatial Science Center of Excellence (GSCE), South Dakota State University, Brookings, SD, United States.
The Brazilian Tropical Moist Forest Biome (BTMFB) is the world’s largest contiguous area of tropical forests and is
prone to frequent burning. Although fire ignitions are predominantly anthropogenic, set deliberately to clear
forest land and for agricultural and pastoral maintenance, the timing and extent of fire may largely be governed
by local environmental conditions and the time since previous fire occurrence. Precipitation controls the fuel
flammability and also the biomass accumulation. Previous research has indicated that the number of satellite
detected fires follow lagged cyclic patterns of precipitation. In this research eight years (2003-2010) of MODerate
resolution Imaging Spectroradiometer (MODIS) Terra and Aqua satellite active fire detections and their Fire
Radiative Power (FRP) retrievals (related to the fire intensity) are considered for all the BTMBF. The antecedent
precipitation derived from the Tropical Rainfall Measuring Mission (TRMM) best-estimate precipitation rate
product accumulated for periods from one month to six months prior to each active fire detection date and
location are considered. The regional number of MODIS active fire detections and the FRP values exhibit an
inverse exponential decrease with the antecedent precipitation. The strongest relationships are observed for
antecedent accumulated precipitation over three months and one month for the number of active fire detections
and the FRP respectively. The relationships are similar across the seven Brazilian States within the BTMFB and
among the eight years. The results indicate that wetter conditions reduce fuel flammability and result in fewer
fires burning with lower intensity. The quantitative relationships developed in this study are expected to be useful
for fire occurrence and emissions modeling in the BTMF.
TITLE: Fires, storms, and water supplies: a case of compound extremes?
Gary J Sheridan1, Petter Nyman1, Christoph Langhans1, Owen Jones2, Patrick N J Lane1
1.
Department of Forest and Ecosystem Science, The University of Melbourne, melbourne, VIC, Australia.
2.
Department of Mathematics and Statistics, The University of Melbourne, melbourne, VIC, Australia.
Intense rainfall events following fire can wash sediment and ash into streams and reservoirs, contaminating water
supplies for cities and towns. Post fire flooding and debris flows damage infrastructure and endanger life. These
kinds of risks which are associated with a combination of two or more events (which may or may not be extreme
when occurring independently) are an example of what the IPCC recently referred to as ‘compound extremes’.
Detailed models exist for modeling fire and erosion events separately, however there have been few attempts to
integrate these models so as to estimate the water quality and infrastructure risks associated with combined fire
and rainfall regimes. This presentation will articulate the issues associated with modeling the compound effects
of fire and subsequent rainfall events on erosion, debris flows and water quality, and will describe and contrast
several new approaches to modeling this problem developed and applied to SE Australian fire prone landscapes
under the influence of climate change.
TITLE: Examining the role of increased climate variability and fire on aboveground net primary productivity and
soil respiration in semiarid grassland
Michell L Thomey1, William Pockman1, Scott L Collins1
1.
Albuquerque, NM, United States.
Climate models for the southwestern United States project increased rainfall variability and prolonged droughts.
Precipitation and temperature are also the primary drivers of fire in the southwest, but the interaction of fire and
increased climate variability in southwestern grasslands is largely unknown. We examined the effects of climate
regime and fire on aboveground net primary production (ANPP) and soil respiration (Rs) in Chihuahuan Desert
Grassland. We present results from an on-going warming experiment (2008 – present) where treatments include:
2oC increase in nighttime temperatures (+ temperature), 50% increase in El Niño winter precipitation (+
precipitation) and all treatment combinations. We hypothesized that: 1) ANPP would decrease in response to +
temperature, 2) spring ANPP would be higher in plots receiving
+ precipitation, 3) Rs would be highest with + temperature and + precipitation, and 4) following fire ANPP would
be highest in + precipitation plots. At present, mean ANPP varies between seasons and according to rainfall
patterns. A dry spring in 2011 decreased ANPP more than a wildfire that occurred at this site in 2009. Pre- fire
spring mean ANPP was dominated by forbs and was highest in + temperature/+ precipitation (12.89 g m-2) plots,
while grasses added the most to post-fire mean ANPP in control (20.19 g m-2) and + temperature (17.85 g m-2)
plots. In contrast, Bouteloua eriopoda the dominant grass species contributed the most to pre-fire fall mean
ANPP in + temperature/+precipitation plots (182.69 g m-2) and there was no treatment effect on post-fire ANPP.
Mean Rs was low across all treatments, but recent post-fire measures show that Rs is consistently higher in +
temperature plots (0.10 µmol CO2 m-2 s-1). Our results indicate that fire and climate variability may alter ANPP,
Rs and species composition which could impact local ecosystem processes. Understanding these changes is
fundamental for estimates of carbon uptake and ecosystem response to climate change scenarios.
TITLE: Projecting climate-driven increases in North American fire activity
Dongdong Wang1, Douglas C Morton2, George James Collatz2
1.
University of Maryland, College Park, MD, United States.
2.
Goddard Space Flight Center, NASA, Greenbelt, MD, United States.
Climate regulates fire activity through controls on vegetation productivity (fuels), lightning ignitions, and
conditions governing fire spread. In many regions of the world, human management also influences the timing,
duration, and extent of fire activity. These coupled interactions between human and natural systems make fire a
complex component of the Earth system. Satellite data provide valuable information on the spatial and temporal
dynamics of recent fire activity, as active fires, burned area, and land cover information can be combined to
separate wildfires from intentional burning for agriculture and forestry. Here, we combined satellite-derived
burned area data with land cover and climate data to assess fire-climate relationships in North America between
2000-2012. We used the latest versions of the Global Fire Emissions Database (GFED) burned area product and
Modern-Era Retrospective Analysis for Research and Applications (MERRA) climate data to develop regional
relationships between burned area and potential evaporation (PE), an integrated dryness metric. Logistic
regression models were developed to link burned area with PE and individual climate variables during and
preceding the fire season, and optimal models were selected based on Akaike Information Criterion (AIC). Overall,
our model explained 85% of the variance in burned area since 2000 across North America. Fire-climate
relationships from the era of satellite observations provide a blueprint for potential changes in fire activity under
scenarios of climate change. We used that blueprint to evaluate potential changes in fire activity over the next 50
years based on twenty models from the Coupled Model Intercomparison Project Phase 5 (CMIP5). All models
suggest an increase of PE under low and high emissions scenarios (Representative Concentration Pathways (RCP)
4.5 and 8.5, respectively), with largest increases in projected burned area across the western US and central
Canada. Overall, near-term climate projections point to pronounced changes in fire season length, total burned
area, and the frequency of extreme events across North America by 2050. Accurately representing wildfires is a
frontier in Earth System modeling, but overly smoothed climatological emissions make it difficult to evaluate
model performance on this front. In this project, we test the ability of conventional and superparameterized
versions of the CESM to represent an acute 2004 wildfire event using the GFEDv3 high frequency emissions. We
use novel methods, constraining model meteorology to data, and tuning default GFEDv3 to better match MODIS
AOD measurements over the source. We also calibrate the vertical structure of emissions against MISR satellite
data in order to make a fair evaluation of the model physics. These effects of fire tuning, redistribution, and the
effect of superparameterized scavenging on the CESM simulations of the wildfire are assessed by comparing
model output against novel lidar and aircraft constraints from the ICARTT field campaign.
TITLE: Testing Frontier Aerosol Physics: Effect of Emissions Source Tuning, Vertical Calibration, and
Superparameterized Scavenging on Simulations of an Acute 2004 Arctic Wildfire Plume in CES
Amy Yu1, Michael S Pritchard1
1.
Earth System Science, University of California, Irvine, Irvine, CA, United States.
Accurately representing wildfires is a frontier in Earth System modeling, but overly smoothed climatological
emissions make it difficult to evaluate model performance on this front. In this project, we test the ability of
conventional and superparameterized versions of the CESM to represent an acute 2004 wildfire event using the
GFEDv3 high frequency emissions. We use novel methods, constraining model meteorology to data, and tuning
default GFEDv3 to better match MODIS AOD measurements over the source. We also calibrate the vertical
structure of emissions against MISR satellite data in order to make a fair evaluation of the model physics. These
effects of fire tuning, redistribution, and the effect of superparameterized scavenging on the CESM simulations of
the wildfire are assessed by comparing model output against novel lidar and aircraft constraints from the ICARTT
field campaign.