ABSTRACTS
CIRMOUNT SESSION AGU 2010
Global Environmental Change (GC)
Ecosystem Responses to Fine-Scale Climate Variability in Mountainous Terrain
Presiding:
G Greenwood, University of Bern, Bern, Switzerland;
J A Hicke, University of Idaho, Moscow;
C I Millar, Sierra Nevada Research Center, USDA Forest Service, Albany;
C Tague, Bren School of Environmental Science and Management, University of California, Santa Barbara,
Santa Barbara
TALKS
Effects of overcast and foggy conditions on transpiration rates of Pinus patula trees along a
chronosequence within the cloud belt of the Sierra Madre Oriental, central Veracruz, Mexico
*Alvarado-Barrientos, M S (susana.alvarado@gmail.com), Natural Resource Ecology and Management, Iowa
State University, Ames, IA, USA
Holwerda, F (friso.holwerda@gmail.com), Natural Resource Ecology and Management, Iowa State
University, Ames, IA, USA
Asbjornsen, H (hasbjorn@iastate.edu), Natural Resource Ecology and Management, Iowa State University,
Ames, IA, USA
Sauer, T (Tom.Sauer@ars.usda.gov), National Laboratory for Agriculture and the Environment, USDA-ARS,
Ames, IA, USA
Dawson, T E (tdawson@berkeley.edu), Integrative Biology, University of California, Berkeley, CA, USA
Bruijnzeel, L A (sampurno.bruijnzeel@falw.vu.nl), Faculty of Earth and Life Sciences, VU University,
Amsterdam, Netherlands
Pinus patula is a native tree species of the montane cloud belt of central Veracruz, Mexico, and one of the
most popular species for regional reforestation efforts, both within and outside its natural range of occurrence.
Projected regional climate change is likely to cause a rise in the average cloud condensation level by several
hundred meters, thereby reducing fog occurrence, whilst overcast conditions are likely to remain similar. To
improve our understanding of how water use of P. patula plantations is affected by changes in climatic
conditions, we analyzed the response of transpiration rates to fine-scale variations in microclimate, particularly
fog immersion and the occurrence of high clouds. We conducted measurements of micrometeorological
parameters and transpiration (Et, using the heat ratio sap flow technique) of 15 pine trees representing a range
of ages (10-34 years) and sizes (7-60 cm of dbh) during one and a half years (Nov 2008 - May 2010), covering
two dry seasons and one wet season. Foggy days were defined using daytime “M-of-N” constructs (at least 4
hours with visibility <1000 m within 6 consecutive hourly observations), and days with overcast conditions as
having a median daytime visibility > 1000 m and a maximum incoming solar radiation (Sin) < 700 W m-2.
Precipitation and leaf wetness data were used to distinguish between (partly) wet and dry canopy conditions.
Daily transpiration rates were normalized for climatic conditions using the FAO reference evaporation ETo to
allow determination of the proportional contributions to Et suppression by reductions in Sin and VPD relative to
leaf wetness. We found that both foggy and overcast conditions without rainfall produced similar % of Et
reduction compared to sunny conditions (60-70%). The strongest Et suppression effects occurred when foggy
or overcast conditions were associated with rainfall. However, there was just a slight and non significant
difference between the average Et/ETo ratio for foggy days with rainfall (i.e. partially wetted canopy) and fogonly days, suggesting that the suppression of Et was mainly caused by reductions in VPD and Sin. Further,
reverse daytime sap flow rates (possibly due to water uptake by tree crowns) occurred almost exclusively
during periods with fog and rainfall, i.e. zero VPD and wet canopy conditions. We also found significant
differences between the response of young and mature pines, as the Et/ETo ratios for both foggy and overcast
conditions declined exponentially with tree age/size. The Et suppression effect of high and low clouds (without
rainfall) likely does not have a major impact on annual water use by P. patula, because these conditions occur
only about 5% of the time during the dry season (when ETo is greatest) and usually in the (late) afternoons
when diurnal transpiration is already declining.
Climate and Floristic Variation in Great Basin Mountain Ranges (Invited)
*Charlet, D A (david.charlet@csn.edu), Biology, College of Southern Nevada, Henderson, NV, USA
Leary, P (pat.leary@csn.edu), Biology, College of Southern Nevada, Henderson, NV, USA
Exponential human population growth in Clark County, Nevada, in the last few decades raised concern
regarding the impact this growth would have on the biota of the surrounding Mojave Desert. The situation
demanded that studies be conducted to understand the relationship between the biota and its environment.
These studies required detailed vegetation information, with greater accuracy than provided by earlier efforts.
We became involved in several projects concerning the vegetation of Clark County that had similar missions,
but covered different areas. We coordinated data collection so that a single, cohesive data set was prepared to
meet everyone’s needs. To add value to all of the projects, we ensured that data would be collected in the
same way so all projects benefitted by being tied into all the other projects. After these projects were
underway, the Nevada System of Higher Education was awarded an NSF EPSCoR grant (Nevada
Infrastructure for Climate Change Science, Education, and Outreach). The grant funds two series of
meteorological stations along long elevation gradients crossing several life zones. One set of five monitoring
stations is in the Sheep Range, about 40 miles north of Las Vegas. The other set of seven stations are in the
Snake Range about 260 miles north of Las Vegas. Meteorological sites were selected to be near the middle of
currently recognized vegetation zones that correspond to Merriam’s Life Zones. The meteorological stations
occur in typical communities in each of the zones, from 2930 ft in the Las Vegas Valley to more than 11,000 ft
in the Snake Range. The stations are outfitted to monitor local meteorological conditions, soil moisture, and
other physical parameters important to plants. We are using the data we are collecting to provide a baseline
survey of biodiversity for the group. To date, more than 2300 vegetation samples were taken in the vicinities of
these climate monitoring transects. Directly associated with the stations are 316 in the Snake Range transect,
and 425 along the Sheep Range transect. Near the Sheep Range lies the Spring Mountains where 769
samples were obtained. More than 30,000 geo-referenced photographs document the sites, and nearly 1000
vascular plant taxa have been encountered and their distributions documented. Recently completed soil maps,
the PRISM precipitation model, and 10m Digital Elevation Models (DEMs) of the study areas exist. As a result,
many environmental conditions can be explored with multivariate statistical methods. Preliminary results
indicate that different kinds of physical data may be appropriate only at certain scales. Most useful for finescale investigations on mountains appears to be measures of irradiance at the solstices and equinox derived
from the 10m DEM. Past climate in Nevada is readily evident on its landscapes, featuring glacial, periglacial
and pluvial features. Pollen and remains left by woodrats provide vegetation records dating up to 40,000 years
before present. The vegetation work described here provides a snapshot of biodiversity at fine scale of several
mountain ranges. Efforts of the physical scientists and physiologists now, and repeat visits to the sample sites
of this study later, will help us track the processes and manifestations of landscape change as responses to
climate.
Modeling plant species distributions under future climates: how fine-scale do climate models need to
be? (Invited)
*Davis, F W (fwd@bren.ucsb.edu), Bren School, University of California, Santa Barbara, CA, USA
Franklin, J (janet.franklin@asu.edu), School of Geographical Sciences and Urban Planning, Arizona State
University, Tempe, AZ, USA
Ikegami, M (mikegami@bren.ucsb.edu), Earth Research Institute, University of California, Santa Barbara, CA,
USA
Syphard, A D (asyphard@yahoo.com), Conservation Biology Institute, La Mesa, CA, USA
Flint, A L (aflint@usgs.gov), California Water Sciences Center, U.S. Geological Survey, Sacramento, CA, USA
Hannah, L (l.hannah@conservation.org), Conservation International, Arlington, VA, USA
The potential importance of local climate refugia for species persistence and migration makes climate
downscaling especially critical for assessing implications of climate change on biodiversity. Recent studies of
scale-dependence in plant species distribution models show high model sensitivity to resolution at local-toregional scales. Using Maximum-Entropy (Maxent), we modeled distributions of 40 California endemic plant
species based on plot occurrence data, soil maps and downscaled climate variables at grid resolutions ranging
from 90 m to 4 km. The species represent a wide range of life histories and range sizes. Species bioclimatic
models based on historical (1970-1999) climate were applied to project late 21st C distributions based on two
global climate models (GFDL, PCM) and two emission scenarios (A2, B1). The broad features of the modeled
species’ distributions were very similar across a 2000-fold change in spatial resolution of climate data,
especially for species with larger ranges. However, local details of predicted distributions, which are of
particular interest to land managers, were much more sensitive to the resolution of input climate data.
Mechanisms Controlling the Effects of Weather and Climate on California's Ecosystems (Invited)
*Goulden, M (mgoulden@uci.edu), Earth System Science, University of California, Irvine, CA, USA
Kelly, A E (a.kelly@uci.edu), Earth System Science, University of California, Irvine, CA, USA
Fellows, A (afellows@uci.edu), Earth System Science, University of California, Irvine, CA, USA
Winston, G (gwinston@uci.edu), Earth System Science, University of California, Irvine, CA, USA
We combined observations and manipulations along topographic gradients in southern and central California
to understand how climate controls ecosystem function. California's topography causes large temperature and
precipitation gradients as a result of orographic, rain-shadow, atmospheric lapse, and sea breeze effects.
These gradients lead to a wide diversity of ecosystem types and provide a natural laboratory for understanding
the controls on plant community composition and ecosystem function. Findings include: (1) Natural climate
gradients drive large changes in species composition, plant phenology, growing season length, and primary
production. The growing season at low, dry, and warm locations is limited by summer drought, resulting in low
primary production. The growing season at high, wet, and cold locations is limited by winter cold, resulting in
low primary production. The growing season at mid elevation is limited by neither summer drought nor winter
cold, resulting in year-round and high primary production. (2) The relative importance of plant species within a
community shifts rapidly in response to changes in water input, caused by either natural variability or
experimental manipulation. Species that are intolerant of drier conditions decline rapidly with reduced water
input, and may disappear locally; species that are tolerant of drier conditions increase rapidly in extent. (3)
Inward plant migration, and the establishment of new species at a location, is a comparatively slow process.
The initial phases of climate change will likely reshuffle the importance of existing species within the
community, resulting in only modest changes in ecosystem function but possibly extirpating species that are
intolerant of warmer and drier conditions, and reducing biodiversity. These declines in biodiversity and delays
in species immigration may ultimately limit the ability of ecosystems to respond to subsequent interannual and
decadal variations in weather, and to adjust to more extreme changes in climate.
http://snri.ucmerced.edu/CZO
The upper mountain forest and tree response to climate change in south Siberian Mountains
*Kharuk, V (kharuk@ksc.krasn.ru), Forest Ecology and Monitoring, Sukachev Institute of Forests,
Krasnoyarsk, Russian Federation
Ranson, J (jon.ranson@nasa.gov), Biospheric Sciences Branch, NASA Goddard Space Flight Center,
Greenbelt, MD, USA
The aim of this study is to evaluate topographic features of high elevation mountain environments govern
spatial distribution and climate-driven dynamics of the forests growing there. The study area included upper
mountain forest stands formed by larch (Larix sibirica Ledeb) and Siberian pine(Pinus sibirica Du Tour)
(elevation range 1800-2600 m) in the mountains of southern Siberia. We used archive maps, satellite and onground data from 1960-2002. Data were normalized to avoid bias caused by uneven distribution of elevation,
and slope steepness within the analyzed area. Spatial distribution of forest stands were analyzed with respect
to topography based on a DEM. The primary results show that mountain forest spatial patterns are anisotropic
with respect to topography. At a given elevation, the majority of forests occupied slopes with greater than mean
slope values. As the elevation increased forests shifted to steeper slopes. The forest azimuth distribution
orientation changed clockwise with elevation increase (total shift was 120 deg) indicating a combined effect of
wind and water stress on the observed forest patterns. Warming caused changes in the forest distribution
patterns during the last four decades. The area of closed forests increased 1.5 times, which was attributed to
increased stand density and tree migration. The migration rate was 1.5 ± 0.9 m yr^-1 and caused a mean
forest line shift of 63 ± 37m. Along with upward migration, downward tree migration onto hill slopes was
observed. Changes in tree morphology were also noted as wide-spread transformation of the prostrate forms
of Siberian pine and larch into erect forms. An analysis of the radial growth increments showed that the
widespread vertical transformation of krummholz began in the mid -1980s. Radial and apical growth
increments correlated with increase in air temperature (summer and “cold period”) and CO2 concentration.
Regeneration responded to temperature increase of 1 deg C by migration to the areas of 10-40 m higher in
elevation. Regeneration has propagated into the alpine tundra at the rate of ~1.0 - 2.0 m/yr. Siberian pine and
larch regeneration surpassed their upper historical limit by 10-80 m in elevation. We will show that spatial
patterns of upper mountain forests as well as forest response to warming strongly depends on topographic
features . With elevation increase (and thus a harsher environment) forests shifted to steep wind-protected
slopes. A considerable increase of the stand area and increased elevation of the upper forest line was
observed coincident with the climate warming that was observed. A warming climate provides competitive
advantages to Siberian pine in areas with sufficient precipitation. Larch is more tolerant of harsh climates and
exhibits an arboreal growth form where Siberian pine is in krummholz form. Warming winter temperatures have
been sufficient for increased survival of regeneration. Larch also has an advantage at the upper tree limit and
in the areas with low precipitation. Climate-induced forest response significantly modified the spatial patterns of
high elevation forests in southern Siberia during the last four decades, as well as tree morphology.
Sensitivity of subalpine tree seedlings and alpine plants to natural and manipulated climate variation:
Initial results from an Alpine Treeline Warming Experiment (Invited)
*Kueppers, L M (lkueppers@ucmerced.edu), University of California, Merced, Merced, CA, USA
Niche models and paleoecological studies indicate that future climate change will alter the geographic
distributions of plant species. Changes in temperature, snowmelt timing, or moisture conditions at one edge of
a species’ range may have different consequences for recruitment, carbon exchange, phenology, and survival
than changes at another edge. Similarly, local genetic adaptation may constrain species and community
responses to climate change. We have established a new experiment to investigate potential shifts in the
distribution of subalpine tree species, and the alpine species they might replace. We are asking how tree
species recruitment and alpine species growth and reproduction vary within their current ranges, and in
response to temperature and soil moisture manipulations. We are also examining whether genetic provenance
and ecosystem processes constrain tree seedling and alpine herb responses. Our Alpine Treeline Warming
Experiment is located across three sites at Niwot Ridge, CO, ranging from near the lower limit of subalpine
forest to alpine tundra. We use infrared heaters to raise growing season surface soil temperatures by 4-5°C,
and to lengthen the growing season. The warming treatment is crossed with a soil moisture manipulation to
distinguish effects due to higher temperatures from those due to drier soil. Each plot is a common garden sown
with high and low elevation provenances of limber pine (Pinus flexilis) and Engelmann spruce (Picea
engelmannii). We established an additional set of experimental plots to examine treatment effects on alpine
species phenology, growth and reproduction. Under ambient conditions in 2009, tree seedling germination
rate, lifespan, and first season survival was higher within the species’ current range than in the alpine, and for
Engelmann spruce, was higher at the low elevation limit than the high elevation limit. Source population (low
vs. high elevation) was a significant factor explaining natural variation in germination rates and timing, seedling
physiology, and seedling survival. In 2010, the first season with experimental effects data, the timing of
germination was substantially advanced with warming for both species, and warming appeared to increase
germination rates for limber pine, but to depress rates for Engelmann spruce at treeline. Seedling carbon
balance was negative at the warmest leaf temperatures and there is some indication that the low elevation
provenance has a higher total assimilation rate and net carbon gain than the high elevation provenance. Water
availability was an important driver of variation in carbon assimilation through the growing season. Our early
results suggest that with higher germination rates and lower mortality rates, limber pine is better able to recruit
into the alpine than Engelmann spruce, and that lower elevation provenances of limber pine are better at
assimilating carbon for growth regardless of site. Ultimate success in seedling establishment may be more
contingent on water availability than temperature, even at these high elevations.
https://alpine.ucmerced.edu/pub/htdocs/index.html
Forest responses to increasing aridity and warmth in the southwestern United States
Still, C J (still@icess.ucsb.edu), Geography, UC Santa Barbara, Santa Barbara, CA, USA
*Williams, P (williams@geog.ucsb.edu), Geography, UC Santa Barbara, Santa Barbara, CA, USA
Allen, C D (craig_allen@usgs.gov), Fort Collins Science Center, US Geological Survey, Los Alamos, NM,
USA
Millar, C I (cmillar@fs.fed.us), Sierra Nevada Research Center, USDA Forest Service, Albany, CA, USA
Swetnam, T W (tswetnam@ltrr.arizona.edu), Laboratory of Tree-Ring Research, University of Arizona,
Tucson, AZ, USA
Michaelsen, J (joel@geog.ucsb.edu), Geography, UC Santa Barbara, Santa Barbara, CA, USA
Leavitt, S W (sleavitt@ltrr.arizona.edu), Laboratory of Tree-Ring Research, University of Arizona, Tucson, AZ,
USA
In recent decades, intense droughts, insect outbreaks, and wildfires have led to decreasing tree growth and
increasing mortality in many temperate forests. We compared annual tree-ring width data from 1,097
populations in the coterminous United States to climate data and evaluated site-specific tree responses to
climate variations throughout the 20th century. For each population, we developed a climate-driven growth
equation using climate records to predict annual ring widths. Forests within the mountain Southwest appear
particularly sensitive to drought and warmth. We input 21st century climate projections to the equations to
predict growth responses. Our results suggest that as projected temperatures rise and precipitation declines
southwestern trees will experience substantially reduced growth during this century, especially at warm, lowerelevation sites. As tree growth declines, mortality rates may also increase at many sites. Increases in wildfires
and bark-beetle outbreaks in the most recent decade are likely related to an extreme drought and high
temperatures during this period. Using satellite imagery and aerial survey data, we conservatively calculate
that ~2.7% of southwestern forest and woodland area experienced substantial mortality due to wildfires from
1984-2006, and ~7.6% experienced mortality associated with bark beetles from 1997-2008. We estimate that
up to ~18% of southwestern forest area (excluding woodlands) experienced mortality due to both bark beetles
and wildfire during this period. Expected climatic changes will alter future forest productivity, disturbance
regimes, and species ranges throughout the Southwest. Emerging knowledge of these impending transitions
informs efforts to adaptively manage southwestern forests.
Map of southwestern forest and woodland mortality due to (orange) bark beetles from 1997-2008 and (red)
wildfire from 1984-2006. Dark green areas are conifer and mixed forest. Light green areas are piñon/juniper
woodland. Grey areas are non-forest/woodland landscapes. White lines are state boundaries. Bark-beetle
induced mortality covered 18,177 km^2 and wildfire induced mortality covered 6,420 km^2.
Do plant species interactions reflect small-scale abiotic gradients in the alpine zone?
*Whitecloud, S S (simone.s.whitecloud@dartmouth.edu), Dartmouth, Hanover, NH, USA
Biotic interactions such as competition and facilitation play a role in determining species distributions and
abiotic factors can determine how these dynamics unfold. Understanding the strength and importance of biotic
interactions is therefore essential to making predictions about community response to changing environmental
conditions. In the alpine zone of New England, plant communities vary along the physical gradients of
mountaintops. Eastern slopes are sheltered from the prevailing westerly winds and produce larger, longerlasting snowdrifts that create potential habitat for boreal forest species to move into the alpine zone. Western
slopes are strictly alpine. The Stress Gradient Hypothesis states that the alpine zone, due to its harsh physical
conditions, is likely to host positive interactions between species (facilitation) (Bertness and Callaway 1994). In
the summer of 2009 I conducted an observational study on peaks of three mountain ranges to quantify how
these physical patterns correlated with changes in plant communities and species interactions. Multivariate
analysis showed effects of aspect and mountain shape (domed or peaked) on plant communities. Twentymeter transects from the peak down the leeward slope also demonstrated a three-cluster pattern that I
hypothesize represents an interaction gradient from facilitation at the peak to competition. Neighbor removal
manipulations were initiated in the summer 2010 to test this hypothesis. Effects will be tested using proxies for
plant growth such as nodal length and leaf surface area measured over the next two years. Evidence for
facilitation will be demonstrated by decreased growth in the absence of neighbors, while increased growth
imply the removal of competitive interactions. I hypothesize that the relative importance of these biotic
interactions will be sensitive to climate change and that species interactions will likely contribute to shifts in
communities in the face of changing climate.
POSTERS
Fine-scale Phenology and Nitrogen-Fixing Microbes at a GLORIA Site in Southwestern Montana, USA
*Apple, M E (mapple@mtech.edu), Biological Sciences, Montana Tech, Butte, MT, USA
Prince, J (jbprince@mtech.edu), Biological Sciences, Montana Tech, Butte, MT, USA
Morales, S (sergio.morales@mso.umt.edu), Biological Sciences, Montana Tech, Butte, MT, USA
Apple, C (jungcharlesmusic@gmail.com), Biological Sciences, Montana Tech, Butte, MT, USA
Gallagher, J (jgallagher@opendap.org), OPeNDAP, Butte, MT, USA
Global climate change is predicted to have a major impact on alpine environments and plants, including
changes in the phenology of alpine plants in western North America. The GLORIA( Global Research Initiative
in Alpine Environments) project is an international network of alpine sites for long-term monitoring of naturallyoccurring alpine plants in the context of climate change. We established a GLORIA site in southwestern
Montana in 2008 with four sub-summits of ascending elevation from treeline to the upper alpine with surveys of
plants in quadrats at each cardinal direction and installed -20° to 50° C temperature loggers (Onset TB132).
This GLORIA site is immediately east of the Continental Divide at Mt. Fleecer, (45°49”36.06”N,
112°48’08.18”W), a 2873 m (9425 ft.) peak situated between the Pintlar and Pioneer Mts., and at Mt. Keokirk,
2987.3 m, (9801 ft.), 45°35’37.94” N, 112°57”03.89” W, south of Mt. Fleecer in the Pioneer Mts. Phenology is
an important aspect of life in the mountains. Herbaceous plants appear at different times throughout the
growing season but can be virtually undetectable at other times. To determine when particular species can be
detected, we constructed a time-series of photographs of plants at the 3m2 and 1m2 quadrats at the subsummits at Mt. Fleecer in the summer of 2010, with the first set of photographs taken on July 9, just after
snowmelt and the final set taken on August 28, just before snowfall. The photographs demonstrate that
apparently new species are found when early and late season images are compared. Data on the timing
intervals of vegetative growth, anthesis, fruiting, and seed dispersal as well as visualizations of the seasonal
appearance and disappearance of the aboveground parts of different species can be extracted from the
photographs in the time series. As a result of this study, several new species will be added to the
Southwestern Montana GLORIA species list, including Gentiana calycosa and Gentiana amarella, which were
in bloom at the treeline site in September 2010 but were not evident during the baseline survey in July 2008.
Because nitrogen fixation is a critical process in alpine environments, the lives of alpine plants are intricately
linked to those of nitrogen-fixing, and often symbiotic, microbes. Therefore, it is not only the plants that may be
affected by changes in climate but also the nitrogen-fixing microbes. To develop an understanding of the
distribution of nitrogen-fixers, we initiated a survey of these microbes by searching for them in lichens,
legumes, and cryptogamic crusts. Lichens from Mt. Fleecer contained photosynthetic green algae but did not
contain nitrogen-fixing cyanobacteria. We have found root nodules with nitrogen-fixing bacteria in Lupinus sp.
but not in Oxytropis campestris, another abundant legume from Mt. Fleecer. In addition, we are using
microscopy to examine cryptogamic crusts of soils from meadows near the treeline and lower alpine subsummits of Mt. Fleecer to determine whether nitrogen-fixing cyanobacteria are present and thus likely
contributing nitrogen to the alpine ecosystem.
Investigating tree mortality at multiple spatial and temporal scales in the Bishop pine forest on Santa
Cruz Island, California
*Baguskas, S A (baguskas@geog.ucsb.edu), UC-Santa Barbara, Santa Barbara, CA, USA
Bookhagen, B (bodo@icess.ucsb.edu), UC-Santa Barbara, Santa Barbara, CA, USA
Peterson, S H (seth@geog.ucsb.edu), UC-Santa Barbara, Santa Barbara, CA, USA
Asner, G P (gpa@stanford.edu), Environmental Earth System Science, Stanford University, Stanford, CA, USA
The rate of tree mortality has increased across the western United States in recent decades, and many studies
attribute the cause to water stress induced by regional warming. To date, the geographical scope of study
regions affected by widespread tree mortality in the American West has largely been limited to continental,
montane climates. Much less is known about mortality events in other climatic regions, such as coastal forests.
The relatively unvarying nature of the coastal, maritime climate has traditionally been assumed to buffer these
forests from large climate variations; however, we have observed rapid tree mortality in this region which
suggests coastal forests may be as susceptible to drought-induced mortality as inland forest locations. Santa
Cruz Island (SCI), one of the California Channel Islands, harbors numerous relict and endemic plant species,
including Bishop pine (Pinus muricata). Following extreme drought in southern California in two of the last
three years (2007-2009), widespread mortality of Bishop pines has become evident. Bishop pine populations
are restricted to the fog belt of coastal California and northern Baja California; therefore, a major reduction of
existing populations on SCI would greatly reduce the distribution of the species as a whole. The focus of my
research is to investigate the mechanisms underlying spatial and temporal patterns of Bishop pine mortality on
SCI. I used remote sensing techniques to characterize spatiotemporal patterns of tree mortality and I have
performed ground-data collection to validate remote-sensing results. Remote sensing in combination with field
verification is a valuable tool to understand the spatiotemporal pattern of tree mortality and is a necessary step
to help elucidate potential environmental and biological controls on tree mortality.
Fire and Climate History of Mixed Conifer Woodlands in the Great Basin, USA
*Biondi, F (fbiondi@unr.edu), DendroLab, University of Nevada, Reno, NV, USA
Bradley, M (meganbradley85@gmail.com), DendroLab, University of Nevada, Reno, NV, USA
Cheek, J (jcheek47@yahoo.com), DendroLab, University of Nevada, Reno, NV, USA
Jamieson, L (kipperpie@gmail.com), DendroLab, University of Nevada, Reno, NV, USA
Kilpatrick, M (mackenziekilpatrick@hotmail.com), DendroLab, University of Nevada, Reno, NV, USA
Sibold, J (Jason.Sibold@colostate.edu), DendroLab, University of Nevada, Reno, NV, USA
Strachan, S D (scotty@dayhike.net), DendroLab, University of Nevada, Reno, NV, USA
We investigated climate, fire, and species dynamics before and after Euro-American settlement at two
locations in Lincoln County, Nevada. Both the Mt. Irish and Clover Mountains sites are isolated high ranges in
the southern Great Basin Desert, not far from the floristic boundary with the northern Mojave Desert. At Mt.
Irish, non-scarred ponderosa pines and single-leaf piñons were used to develop a tree-ring reconstruction of
drought (mean PDSI for May-July, NV Clim. Div. 3) from 1396 to 2003. Fire-scarred ponderosas found at both
study areas were then sampled, and crossdated fire-scar records were used to generate the fire history. A total
of 12 plots, each 0.1 ha in size, was sampled at each site to quantify stand structure, age of surviving trees,
and fuel loads. Additional information on species dynamics were collected at regularly spaced grid points.
Density of pinyon pine at both sites has more than doubled since Euro-American settlement, with peak
survivorship occurring in 1900-1940 at Mount Irish and 1930-1970 at the Clover Mountains. Pre-settlement
trees occur throughout each site, particularly at Mount Irish, where in 1550-1860 fires that scarred at least two
trees were very frequent (mean fire return interval: 4 years), while fires that scarred at least 10% of the
recorder trees were relatively rare (mean fire return interval: 66 years). At the Clover Mountains, for the period
1785-2007, fires that scarred at least two trees and fires that scarred at least 10% of the recorder trees had
more similar mean fire return intervals: 7 and 12 years. Fire frequency did not decrease during the 1780-1840
period, when fire was reduced or absent in other areas of the western United States. Much lower fire frequency
was noted after Euro-American settlement at Mt. Irish, most likely because of less favorable climatic
conditions, while the difference was less pronounced, and also affected by fire suppression activity, at the
Clover Mountains. Fuel loads at the two sites were different, with those at the Clover Mountains favoring a
higher rate of surface fire spread compared to Mount Irish, which however is currently at a greater risk for a
high-intensity crown fire. In addition, based on fuel reconstructions, a potential change in fire behavior from a
surface to a crown fire occurred after settlement at the Clover Mountains and prior to settlement at Mount Irish.
Modeling the Response of Glaciers to Climate Change in the Upper North Saskatchewan River Basin
*Booth, E (evan.booth@uleth.ca), University of Lethbridge, Lethbridge, AB, Canada
Byrne, J M (byrne@uleth.ca), University of Lethbridge, Lethbridge, AB, Canada
Jiskoot, H (hester.jiskoot@uleth.ca), University of Lethbridge, Lethbridge, AB, Canada
MacDonald, R J (ryan.macdonald@uleth.ca), University of Lethbridge, Lethbridge, AB, Canada
This research will quantify the historical and future impacts of climate change on the glacial contribution to
stream flow in the Upper North Saskatchewan River basin, Alberta, Canada. The physically based Generate
Earth SYstems Science (GENESYS) hydromet model will be used to analyze the regional impact of historical
data, and to forecast future trends in the hydrology and climatology of selected watersheds within the basin.
This model has recently been successfully applied to the St. Mary River watershed, Montana, as well as the
Upper North Saskatchewan River basin (MacDonald et al. 2009; MacDonald et al. in press; Byrne et al. in
review). Hydro-meteorological processes were simulated at a high temporal and spatial resolution over
complex terrain, focusing on modeling snow water equivalent and the timing of spring melt. A mass-balance
glacier model will be developed and incorporated into GENESYS to more accurately gauge the effects of
climate change on glacial decline and the effects of these changes on stream runoff. Global Climate Model
(GCM) scenarios will be applied through GENESYS to develop meaningful projections of the range of possible
future hydrologic change under reduced glacial cover in the basin through 2100.
Building Topographically Modified Tree-Ring Chronologies from High Elevation Bristlecone Pine in the
White Mountains of California, USA
*Bunn, A G (andy.bunn@wwu.edu), Environmental Sciences, Western Washington University, Bellingham,
WA, USA
Hughes, M K (mhughes@ltrr.arizona.edu), Laboratory of Tree-Ring Research, University of Arizona, Tucson,
AZ, USA
Salzer, M W (msalzer@ltrr.arizona.edu ), Laboratory of Tree-Ring Research, University of Arizona, Tucson,
AZ, USA
We analyze growth rates of dozens of high elevation (~3400 m.a.s.l.) bristlecone pine trees (Pinus longaeva
D.K. Bailey) from the White Mountains of California, USA by exploiting the biophysical position of the individual
trees. Recent work has shown that 20th century growth in the highest elevation bristlecone pine is greater than
at any point in recent millennia. This phenomenon is coincident with increased temperatures over the
instrumental climate record. While both temperature and moisture availability appear to influence growth, the
trade-off of these limiting factors is not well understood. The White Mountains are dominated by steep, rugged
terrain. We suggest that even in relatively small areas, the complexity of terrain in high mountain systems can
alter the limiting growth factors of individual trees and that these differences may be of value to better
understand bristlecone pine growth. In a multivariate analysis we are able to isolate different patterns of growth
based that are associated with topographic indices reflecting variations in local temperature lapse rates and
soil moisture anomalies. When we build topographically modified mean ring-width chronologies along these
gradients we find substantial variation between the chronologies in the time and frequency domains. We also
find that the correlations with the instrumental climate record vary and that we are partially able to unmix
temperature versus precipitation signals. These differences appear consistent with mechanistic understanding
of the control of tree-ring variability using a process-based model. If these results are robust, the calculation of
climate reconstructions using ring-width data from these trees could be placed on a firmer, clearer, basis.
Subalpine Conifer Seedling Demographics: Species Responses to Climate Manipulations Across an
Elevational Gradient at Niwot Ridge, Colorado
*Castanha, C (ccastanha@lbl.gov), LBNL, Berkeley, CA, USA
Germino, M J (germmatt@isu.edu), Idaho State University, Pocatello, ID, USA
Torn, M S (mstorn@lbl.gov), LBNL, Berkeley, CA, USA
Ferrenberg, S (scott.ferrenberg@colorado.edu), CU Boulder, Boulder, CO, USA
Harte, J (jharte@berkeley.edu), UC Berkeley, Berkeley, CA, USA
Kueppers, L M (lkueppers@ucmerced.edu), UC Merced, Merced, CA, USA
The effect of climate change on future ranges of treeline species is poorly understood. For example, it is not
known whether trees will recruit into the alpine, above the current treeline, and whether population-level
differences in trees will mediate range shifts. At Niwot Ridge, Colorado, we used common gardens and climate
manipulations to test predictions that warming will lead to greater recruitment at and beyond the cold edge of
these species ranges, and will reduce recruitment at the warm edge. Seed from local populations of limber
pine and Englemann spruce was harvested and reciprocally planted in 3 experimental sites spanning an
elevation gradient from lower subalpine forest (10,000’), to the upper subalpine treeline ecotone (11,000’), to
the alpine tundra (11,300’). In Fall 2009 seeds were sown into 20 plots at each site. Overhead infrared heaters
targeted increases in growing season surface soil temperature of 4-5°C. The heating treatment, which began
in October 2009, was crossed with manual watering, which was initiated following snowmelt in 2010. Over the
2010 growing season, we surveyed seedling germination and mortality weekly. Germination began in early
May at the forest site, in early June at the krummholz site, and in early July at the alpine site. Depending on the
site and plot, heating accelerated germination by 1 to 4 weeks. Seed source elevation, species, and site all
affected germination, with effects for the two species also depending on site. At all sites, lower elevation,
warm-edge populations had higher germination rates than high-elevation, cool-edge populations, indicating a
potential bottleneck for germination of the high elevation seed sources in the adjacent alpine tundra. At all
sites, survival was generally higher for pine than for spruce. Watering tended to enhance pine germinant
survival while heating tended to depress spruce germinant survival. Our results indicate that the alpine tundra,
generally considered an inhospitable environment, was not favorable for Englemann spruce, even with
warming. In contrast, once seeds were introduced, the alpine tundra proved favorable to limber pine
germination, irrespective of the climate manipulation.
20th Century Climate Change in the Sierra Nevada from PRISM Data
*Conklin, D R (david.conklin@oregonstate.edu), Conservation Biology Institute, Corvallis, OR, USA
Osborne-gowey, J D (osbornegowey@hotmail.com), Conservation Biology Institute, Corvallis, OR, USA
Initial estimates of climate warming in the Sierra Nevada during the 20th century were based on instrumental
records from a few long-term weather stations. The PRISM model produces climate maps based on essentially
all available station records. Analysis of PRISM data covering the 20th century for the Yosemite region
suggested that the initial estimates were substantially too large. The analysis is now being extended to the
entire Sierra Nevada range. Quantification of the amount of climate change in the recent past is important to
the interpretation of observed species range shifts during the same period, and to the projection of future range
shifts resulting from even larger climate changes expected in the 21st century.
Soil moisture dynamics and forest fire risk in the Upper North Saskatchewan Watershed, Alberta
*Dalla Vicenza, S A (sarah.dallavicenza@uleth.ca), Geography /Water Env Centre, University of Lethbridge,
Lethbridge, AB, Canada
Byrne, J M (byrne@uleth.ca), Geography /Water Env Centre, University of Lethbridge, Lethbridge, AB,
Canada
Letts, M G (matthew.letts@uleth.ca), Geography /Water Env Centre, University of Lethbridge, Lethbridge, AB,
Canada
The key objective of this research is to assess soil moisture dynamics and forest fire risk as part of an ongoing
study assessing water quantity and quality in the Upper North Saskatchewan watershed. The 20, 000 km2
watershed is located in the Rocky Mountains of west-central Alberta. Forest fires are becoming an increasing
concern as climate change advances along the eastern slopes of the Rocky Mountains of Alberta, as well as
for mountain landscapes worldwide. Global climate change is expected to alter precipitation patterns and
intensities and increase temperatures. Rising temperatures can cause decreases in soil moisture and as a
result, drier forests and organic soils. The hypothesis to be tested is - will global warming lead to greater forest
fire index values (greater risk) and greater duration of high risk index values? A range of climate change
scenarios has been chosen to predict potential effects on future forest fire risk for over 900 distinct terrain
categories (TC) in the watershed. The goal of this research is to further develop a methodology for predicting
the potential frequency or probability of forest fire occurrence. The GENESYS (Generate Earth Systems
Science input) hydrometeorology model and the Canadian Forest Fire Weather Index System are being
combined to assess possible changes in forest fire occurrence and extent in mountain environments.
Subsurface Thermal and Hydrological Changes Between Forest and Clear-cut Sites in the Oregon
Cascades
*Davis, M G (volcdavis@yahoo.com), University of Utah, Salt Lake City, UT, USA
Waschmann, R S (Waschmann.Ron@epamail.epa.gov), U.S. Environmental Protection Agency, Corvallis,
OR, USA
Harris, R N (rharris@coas.oregonstate.edu), Oregon State University, Corvallis, OR, USA
Chapman, D S (david.chapman@utah.edu), University of Utah, Salt Lake City, UT, USA
The Cascades of the US Pacific Northwest are a climatically sensitive area. Projections of continued winter
warming in this area are expected to induce a switch from a snow-dominated to a rain-dominated winter
precipitation regime with a likely impact on subsurface thermal and hydrological regimes. Such changes to the
ecosystem may also be linked to changes in land cover, resulting in amplified subsurface temperatures and
changing the timing and availability of subsurface water. To monitor changing climatic conditions in this region,
the Environmental Protection Agency established pairs of meteorological stations over the Santiam Pass,
Cascades Mountains, Oregon, USA, at 5 locations spanning elevations between 500 to 1200 m in the late
1990s. Each location comprises two separate meteorological towers; one under the old-growth coniferous
forest canopy and the other in a near by opening or clear-cut. One purpose of the paired stations is to
understand the influence of the forest canopy and the developing clear-cut vegetation on the seasonal and
annual soil moisture and temperature at each station. We report a comparison of observations between paired
stations and a comparison between observations and a land surface model. Preliminary results indicate that
open areas have higher air and soil temperatures and receive greater amounts of precipitation and incoming
radiation. These conditions are contrasted with the muted conditions under the forest canopy. The results have
implications for understanding surface energy exchanges, their impact on the subsurface thermal and
hydrological regimes, and possible feedbacks to the climate system as a function of time, space and land
cover.
Climate contributes to zonal forest mortality in Southern California’s San Jacinto Mountains
*Fellows, A (afellows@uci.edu), University of California, Irvine, Irvine, CA, USA
Goulden, M (mgoulden@uci.edu), University of California, Irvine, Irvine, CA, USA
An estimated 4.6 million trees died over ~375,000 acres of Southern California forest in 2002-2004. This
mortality punctuated a decline in forest health that has been attributed to air pollution, stem densification, or
drought. Bark beetles were the proximate cause of most tree death but the underlying cause of this extensive
mortality is arguably poor forest health. We investigated the contributions that climate, particularly drought,
played in tree mortality and how physiological drought stress may have structured the observed patterns of
mortality. Field surveys showed that conifer mortality was zonal in the San Jacinto Mountains of Southern
California. The proportion of conifer mortality increased with decreasing elevation (p=0.01). Mid-elevation
conifers (White Fir, Incense Cedar, Coulter Pine, Sugar Pine, Ponderosa and Jeffrey Pine) died in the lower
portions of their respective ranges, which resulted in an upslope lean in species’ distribution and an upslope
shift in species’ mean elevation. Long-term precipitation (P) is consistent with elevation over the conifer
elevation range (p=0.43). Potential evapotranspiration (ET) estimated by Penman Monteith declines with
elevation by nearly half over the same range. These trends suggest that ET, more than P, is critical in
structuring the elevational trend in drought stress and may have contributed to the patterns of mortality that
occurred in 2002-04. Physiological measurements in a mild drought year (2009) showed late summer declines
in plant water availability with decreasing elevation (p < 0.01) and concomitant reductions in carbon
assimilation and stomatal conductance with decreasing elevation. We tie these observations together with a
simple water balance model.
Above treeline shrub-chronologies on the eastern Sierra Nevada crest, Mono Co., California, USA
contain records of precipitation and large-scale ocean and atmospheric conditions
*Franklin, R S (rebecca@ltrr.arizona.edu), Laboratory of Tree-Ring Research, University of Arizona, Tucson,
AZ, USA
Herb- or shrub- chronology, a technique adapted from dendrochronology, is the study of the annual growth
rings in roots of certain perennial dicotyledonous plants. The presence of annual growth increments in highelevation plants is significant as it highlights the importance of herbchronology for climatic, ecological and
geomorphologic applications in alpine and extra-arboreal regions. For an above-treeline site on the eastern
crest of the Sierra Nevada range at the Barney Lake Rock Glacier (37.56466N, 118.96554W), I will discuss the
dendrochronological potential of several species colonizing this rock glacier with a focus on the ring-width
chronology and climate response of the species Linanthus pungens (Torr.) J.M. Porter & L.A. Johnson.
Commonly known as Granite Gilia, this species is a low-branching shrub (10 - 20 cm H) native to California
and is found throughout the arid mountainous western US and British Columbia at elevations ranging from
1500 - 3700 m. The Barney Lake Rock Glacier (BLRG) chronology is 112 years in length with sufficient sample
replication (EPS>0.85) from 1952 through 2008. In an exploration of the BLRG chronology, I will 1) discuss the
preferential presence of these plants on specific periglacial landforms; 2) present an analysis of correlations
with PRISM climate data, SNOTEL April snow water equivalent (SWE), Palmer Drought Severity Index (PDSI),
Multivariate ENSO Index (MEI), Pacific Decadal Oscillation (PDO) and local climate station temperature and
precipitation records; and 3) discuss the change in response of the BLRG chronology to these variables that
occurs across the 1975/1976 shift from a “cool regime” to a “warm regime” of the California Current, related to
the PDO.
Dry season foliar fog uptake, reverse sapflow, and nighttime transpiration in the tropical montane
cloud forests of Mexico
*Gotsch, S G (sybilgotsch@gmail.com), Natural Resource Ecology and Management, Iowa State University,
Ames, IA, USA
Asbjornsen, H (hasbjorn@iastate.edu), Natural Resource Ecology and Management, Iowa State University,
Ames, IA, USA
Holwerda, F (friso.holwerda@gmail.com), Natural Resource Ecology and Management, Iowa State
University, Ames, IA, USA
Goldsmith, G R (grgoldsmith@berkeley.edu), Integrative Biology, UC-Berkeley, Berkeley, CA, USA
Dawson, T E (tdawson@berkeley.edu), Integrative Biology, UC-Berkeley, Berkeley, CA, USA
Dry season fog is a ubiquitous feature of seasonal tropical cloud forests. Although cloud forests receive
generous inputs of yearly precipitation, rainfall occurs primarily in the wet season. In the tropical montane
forests of Veracruz Mexico, 80% of rainfall occurs in the wet season while fog occurs primarily in the dry
season. Since dry-season fog occurs during months when precipitation is low or absent, this meteorological
phenomenon may be important in alleviating dry-season water stress either directly through foliar fog uptake,
or indirectly through a reduction in transpiration causing relaxation in xylem water tension. We determined the
importance of fog on the water relations of a dominant tropical montane forest tree in La Cortadura Reserve in
Veracruz, Mexico by using micrometeorological data and by measuring sap flow, leaf water potential and
stomatal conductance throughout the canopies of three mature oak trees. Although the relative humidity is
generally high in this habitat, in the dry season, humidity is lower and at times can be as low as 20% which
causes high vapor pressure deficit and evaporative demand. We also screened sap flow data to detect periods
of nighttime transpiration. Reverse sap flow occurred frequently in this site during periods of fog/drizzle. Foliar
fog uptake occurred 30% of the time in the dry season although this reverse flow is likely insignificant in the
water balance of cloud forest trees. Furthermore we detected low, but positive, flow rates flow at night. Finally,
we conducted diurnal courses of leaf water potential and stomatal conductance at the end of the dry season to
determine whether these trees were undergoing water stress. Results/Conclusions We found that reverse sap
flow is a common phenomena in the dry season, indicating foliar fog uptake. Although the addition of fog to
whole-tree water balance may be minimal, high dry season leaf water potential may indicate the importance of
fog in reducing the negative physiological impact of dry periods. Nighttime transpiration is also a common
phenomena in these forests and accounts for approximately 30% of total water transpired in the dry season.
Climate change scenarios often predict a reduction of fog in montane habitats; our results indicate that this
may have important repercussions on the physiology of montane forest trees and persistence of montane
cloud forest vegetation in this region.
Alpine ecosystem vulnerability to climate change on the Tibetan Plateau: Global implications for
carbon balance, regional consequences for local pastoralists
*Hopping, K A (kelly.hopping@colostate.edu), Graduate Degree Program in Ecology, Colorado State
University, Ft. Collins, CO, USA
Klein, J A (jklein@warnercnr.colostate.edu), Graduate Degree Program in Ecology, Colorado State University,
Ft. Collins, CO, USA
Hu, J (jiahu@ucar.edu), Atmospheric Chemistry Division, National Center for Atmospheric Research,
Boulder, CO, USA
Kang, S (shichang.kang@itpcas.ac.cn), Institute of Tibetan Plateau Research, Chinese Academy of
Sciences, Beijing, China
The Tibetan Plateau is predicted to undergo climate warming much greater than the global average, as well as
shifts in its currently monsoon-dominated precipitation regime. These changes will likely affect the vegetation
composition, carbon balance, and nutrient cycling of this alpine, social-ecological system. In 2009 we
established a fully factorial experiment to test ecosystem responses to predicted climate changes on the
Tibetan Plateau. Our experiment site (4870 m) is located in the foothills of the Nyanchenthanglha Mountains,
where local pastoralists graze their livestock. The site is representative of central Tibet’s alpine meadow
ecosystems, with the turf-forming sedge, Kobresia pygmaea, as both the dominant species and preferred
forage of yaks. Our climate treatments are spring snow addition, which is added at 1-m depth to simulate
severe snowstorms, and warming with open top chambers, which elevate air temperatures by an average of
1.2 degrees Celsius. The climate treatments are fully crossed with controlled grazing by yaks, which
represents the primary livelihood practice of herders at our study site and throughout Tibet’s grasslands. To
better understand the ecosystem shifts that may occur under climate change in this alpine system and to
elucidate the drivers of these shifts, we collected data from a suite of measurements in each of our plots. Using
a LiCOR 6400 infrared gas analyzer, we measured CO2 fluxes at 4 periods throughout the growing season to
obtain values for net ecosystem productivity (NEP), ecosystem respiration, and gross primary productivity. We
also measured available nitrogen (N) across three distinct moisture regimes (snowmelt, dry-down, and
monsoon). Finally, we quantified changes in vegetation composition and recorded air and soil temperature and
soil moisture throughout the growing season. After two years of applying treatments, our findings suggest that
Tibet’s alpine grasslands are particularly vulnerable to climate change. We will present data indicating that soil
moisture drying seems to be the proximate cause of shifts in vegetation composition, NEP, and N availability,
with climate warming as the ultimate cause. Our results also indicate that some of the negative effects of
warming may be mitigated by spring snowstorms that provide a pulse of moisture at the start of the growing
season. However, in contrast to temperatures that are expected to rise steadily under climate change, snow
events on the Tibetan Plateau are much less predictable across both time and space. This mismatch in
increased rates of warming and added precipitation to the system will likely affect the landscape patchily.
Furthermore, it will leave local herders with the conundrum of how to cope most successfully with the impacts
of multiple climate changes, thus illustrating the complexity associated with integrating a fine-scale
understanding of ecosystem responses to climate change with coherent strategies for adaptation.
Complimentary And Dense Sensor Networks To Understand Climate Variability In Mountainous Terrain
Isaak, D (disaak@fs.fed.us), US Forest Service - Rocky Mountain Research Station, Boise, ID, USA
Holden, Z (zaholden@fs.fed.us), US Forest Service - Region 1, Missoula, MT, USA
*Luce, C (cluce@fs.fed.us), US Forest Service - Rocky Mountain Research Station, Boise, ID, USA
Roper, B (broper@fs.fed.us), US Forest Service - Fish & Aquatic Ecology Unit, Logan, UT, USA
Climate change is motivating extensive research to understand potential future responses in terrestrial and
aquatic ecosystems, including relative spatial vulnerability. Ongoing efforts to downscale climate models is
improving the resolution at which climate data are available, but outputs from the latest regional climate models
remain coarse relative to the scales at which ecological processes operate and landscapes and natural
resources are managed. Inexpensive digital sensors and remote sensing technology now facilitate the
collection of copious amounts of information on a variety of environmental attributes. Within two large mountain
river basins (>5,000km2) of contrasting physiographies in the northern Rockies, we have instrumented dense
networks that consist of hundreds of sensors for stream temperature and air temperature. Numerous research
questions regarding fine-scale climate variation will be addressed with data from each sensor network, such as
the influence of physiography on temperature variation (e.g. cold air drainage and pooling, potential
groundwater buffering of stream temperatures), the relative magnitude of site versus network variation, and
land surface-air temperature feedbacks. The complimentary network approach also facilitates addressing a
host of additional research questions not possible with a single network (e.g., do streams warm because of
local air temperature increases or because some streams are more sensitive than others?). Additional sensor
networks focused on snowmelt timing, stream flow, or other relevant environmental attributes could further
enhance our understanding of the flow of materials and energy through these river basins and mountain
landscapes in general. Development and strategic coordination of similar dense networks across a range of
mountain environments in the western US or globally could provide valuable insights regarding potential
ecosystem responses to climate change and how variability is structured across multiple scales.
Analyzing the Locations, Severity and Frequency of Cold Air Pools (CAP) in the Sierra Nevada,
California
Kunz, A (axel.kunz2@uni-jena.de), Geoinformatics, Hydrology and Modelling, Friedrich Schiller University,
Jena, Germany
*Helmschrot, J (joerg.helmschrot@uni-jena.de), Geoinformatics, Hydrology and Modelling, Friedrich Schiller
University, Jena, Germany
Lundquist, J D (jdlund@u.washington.edu), Civil and Environmental Engineering, University of Washington,
Seattle, WA, USA
The accumulation of cold air in valleys or depressions resulting from nocturnal cooling is a widely recognized
phenomenon in local climatology, particularly in mountainous regions. This nocturnal cooling can significantly
affect ecological patterns and hydro-climatological dynamics in watersheds in complex terrain. Thus,
information on cold air pooling is considered important for basin ecological and hydrological modeling. In this
study, a Cold Air Pool (CAP) map has been created for the entire Sierra Nevada, California. Therefore, 51
Digital Elevation Models (DEM) tiles were processed and analyzed using an approach developed at the
University of Washington (Lundquist et al. 2008). From this map it was shown that 23 % of the Sierra Nevada
is likely affected by cold air pooling, 49 % of the region is not affected by CAP, and 28 % of the region falls in
between these categories. Comparing the map with station data available from the California Data Exchange
Center (CDEC) it was found that the majority of climate stations are established in CAP areas, which are often
located in valleys. The authors argue that this overrepresentation should be considered for the calculation and
regionalization of long-term temperature averages. Since the CAP map only indicates areas of likely cold air
pooling, and does not indicate the severity of the temperature depressions, the map was validated with
temperature data to test the severity and frequency of cold air pools in three test sites located in the northern,
central and southern Sierra Nevada. For those test sites, quality-controlled temperature data from stations
located in CAP and non-CAP areas at comparable elevations were analyzed to better understand the
frequency of CAP events and regional differences in cold air pooling in the Sierra Nevada. It was shown that
cold air pooling is evident in all three regions. With respect to its ecological importance, specific attention has
been given to the seasonal occurrence and intensity of cold air pools in those test regions. The results indicate
that there are significant seasonal changes for CAP events. Based on this study, the authors suggest that
research on ecological and hydro-climatological dynamics in the Sierra Nevada should address the
phenomenon of Cold Air Pooling.
Geologic and geomorphic controls of altitudinal treeline in the Canadian Rocky Mountains
*Macias Fauria, M (mmaciasf@ucalgary.ca), Biogeoscience Institute, University of Calgary, Calgary, AB,
Canada
Johnson, E A (johnsone@ucalgary.ca), Biogeoscience Institute, University of Calgary, Calgary, AB, Canada
We hypothesize that a multi-scale (in both time and space) process competition affecting topographical shelter
(e.g. sites favoring snow accumulation which prevents dissecation and abrasion), and substrate and water
availability, ultimately set the distribution of suitable sites where trees can establish and survive in the
altitudinal treeline. Terrain characteristics on which altitudinal treelines occur are ultimately set by geological
history, which determines the distribution of slope aspects, angles, and lengths, as well as the distribution,
depth, transport, and texture of the regolith on which trees grow. Erosive processes (landscape evolution)
create concave features where flow converges (water, avalanches, debris) - channels - and convex or planar
slopes. A spatially explicit model is presented at 1m resolution which predicts tree presence on a ~ 200 km2
area in the Front Ranges of the Canadian Rocky Mountains as a function of landscape topographical variables
key in water and energy balances and surface transport/instability. The model was validated with independent
data from an adjacent area and successfully captures tree presence/absence. Subalpine forests form a mosaic
of stand ages which is a function of the last disturbance (mostly wildfire), where the main differences from their
lowland counterparts are 1) a higher portion of areas where stand dynamics are affected by disturbances
linked to the presence of slopes (i.e. gravitational: avalanches, flooding/flushing events), and 2) an upslope
declining frequency of sites favorable for tree establishment and survival. Thus, the presence of trees in the
uppermost part of these forests largely depends on the existence of suitable conditions largely linked to
topography. Such places are the result of geomorphologic processes acting on a framework set by the
structural geology of the region, and thus the appearance of new sites suitable for tree growth does not depend
on short (i.e. yearly to decadal) time scales but on longer ones (i.e. centuries to millennia). This view is
supported by the observation from available air photos that over the last > 60yr in our study region treeline has
not risen (except for very few new individuals) despite an increase in temperatures in the area. Moreover, the
treed locations have remained the same in these decades, suggesting that trees grow in suitable areas as
described above. Only forest recovery after disturbances has shown significant landscape-scale changes over
the last seven decades. Slopes with very specific characteristics (very rare in our study area, but potentially
more abundant in other geological environments) may exhibit suitable habitats above the current treeline
susceptible to being colonized by trees in an scenario of climate amelioration. We argue that these precisely
constitute the slopes over which most treeline studies have been carried out (bias towards positive evidence).
Moreover, the fact that the suitability of a site for tree growth is set by a competition of processes which are
affected by climate in different ways and rates impedes a concrete definition of what is 'climatic amelioration'
for treeline.
Assessing stream temperature response to environmental change
*MacDonald, R J (ryan.macdonald@uleth.ca), Univ Lethbridge, Lethbridge, AB, Canada
Boon, S (sarah.boon@uleth.ca), Univ Lethbridge, Lethbridge, AB, Canada
Byrne, J M (byrne@uleth.ca), Univ Lethbridge, Lethbridge, AB, Canada
Stream temperature controls aquatic ecosystem function by directly influencing water quality, ecosystem
productivity, and the physiological functioning of aquatic organisms. To date, there are limited studies of the
impacts of environmental disturbance on stream temperature, particularly on the eastern slopes of the Rocky
Mountains. This region provides key habitat for native salmonid species such as westslope cutthroat trout
(Oncorhynchus clarkii lewisi) and bull trout (Salvelinus confluentus), which are listed as ‘threatened’ and
‘species of special concern’, respectively. Increases in stream temperature could limit habitat availability,
reduce competitive advantage, and potentially increase mortality rates for these native species. This study
uses field data collected at high spatiotemporal resolution to develop a spatial stream temperature model that
simulates the mass and energy balance of the stream system. Preliminary field results demonstrate the high
spatial and temporal variability in processes governing stream temperature in three study stream reaches.
Groundwater/surface water interactions, topographic setting, and local meteorological conditions all contribute
in determining stream thermal regimes. This work discusses how these primary drivers of stream temperature
can be incorporated into a physically based spatial model, and demonstrates how depending on the scale of
interest, the temperature of a stream can be governed by very different contributing factors.
Mortality in Subalpine Forests of the Sierra Nevada, California, USA: Differential Response of Pines
(Pinus albicaulis and P. flexilis) to Climate Variability
*Millar, C I (cmillar@fs.fed.us), Sierra Nevada Research Center, USDA Forest Service, Albany, CA, USA
Westfall, R D (bwestfall@fs.fed.us), Sierra Nevada Research Center, USDA Forest Service, Albany, CA, USA
Delany, D L (ddelany@fs.fed.us), Sierra Nevada Research Center, USDA Forest Service, Albany, CA, USA
Widespread forest mortality in high-elevation forests has been increasing across western North American
mountains in recent years, with climate, insects, and disease the primary causes. Subalpine forests in the
eastern Sierra Nevada, by contrast, have experienced far less mortality than other ranges, and mortality events
have been patchy and episodic. This situation, and lack of significant effect of non-native white-pine blister
rust, enable investigation of fine-scale response of two subalpine Sierran species, whitebark pine (Pinus
albicaulis, PiAl) and limber pine (P. flexilis, PiFl), to climate variability. We report similarities and differences
between the two major mortality events in these pines in the last 150 years: 1988-1992 for PiFl and 2006ongoing for PiAl. In both species, the events occurred within monotypic, closed-canopy, relatively young stands
(< 200 yrs PiAl, < 300 yrs in PiFl); were localized to central-eastern Sierra Nevada; and occurred at 2740-2840
m along the eastern edge of the escarpment on north/northeast aspects with slopes > 40%. Mortality patches
averaged 40-80 ha in both species, with mean stand mortality of trees > 10 cm diameter 91% in PiAl and 60%
in PiFl. The ultimate cause of tree death was mountain pine beetle (Dendroctonus ponderosae) in both
species, with increasing 20th/21st C minimum temperatures combined with drought the pre-conditioning
factors. Overall growth in the past 150 years suggests that PiFl is more drought hardy than PiAl but responds
sensitively to the combined effects of drought and increasing warmth. After the 1988-1992 drought, surviving
PiFl recovered growth. PiAl trees grew very poorly during that drought, and continued poor growth in the years
until 2006 when the mortality event occurred in PiAl. A significant species effect is the apparent difference in
levels of within-stand genetic diversity for climate factors. Differential growth between 19th C (cool, wet) and
20th/21st C (warming, drying) of PiFl trees that died versus survivors indicates that considerable within-stand
genetic diversity for climate existed in PiFl. For PiFl, the late 20th C mortality event acted as strong natural
selection to improve within-stand fitness for warmer and drier conditions. PiFl trees that survived the 19881992 drought remained healthy through subsequent droughts, including the drought that is currently causing
PiAl mortality. By contrast, the PiAl stands do not appear to have contained adaptive genetic diversity for
drought and warmth, and PiAl trees growth behavior over the past 150 years was similar in pattern to the PiFl
trees that died. As a result, the mortality event in PiAl is creating forest openings, with unknown future stand
conditions, rather than rapid within-species adaptation that occurred in PiFl.
Sensitivity of limber pine (Pinus flexilis) seedling physiology to elevation, warming, and water
availability across a timberline ecotone
*Moyes, A B (abmoyes@yahoo.com), UC Merced, Merced, CA, USA
Castanha, C (ccastanha@lbl.gov), Lawrence Berkeley National Lab, Berkeley, CA, USA
Ferrenberg, S (scott.ferrenberg@colorado.edu), UC Merced, Merced, CA, USA
Germino, M J (germmatt@isu.edu), Idaho State University, Pocatello, ID, USA
Kueppers, L M (lkueppers@ucmerced.edu), UC Merced, Merced, CA, USA
Treelines occur where environmental gradients such as temperature become limiting to tree establishment,
and are thus likely to respond to changes in climate. We collected gas exchange, water potential, and
fluorescence measurements from limber pine (Pinus flexilis) seedlings planted into experimental plots at three
elevations at Niwot Ridge, Colorado, ranging from within forest to alpine. At each site seeds from local high-
and low-elevation populations were sewn into replicated and controlled watering and infrared heating treatment
plots. Heating led to earlier snowmelt, germination, and soil moisture availability in spring; higher soil surface
temperatures throughout the growing season; and drier soils in late summer. Assimilation rates in all plots were
most strongly associated with soil moisture availability following germination, and decreased as soils dried over
the growing season. Intrinsic water use efficiency was consistent for the two source populations, but there was
evidence that individuals germinating from high-elevation seeds respired more per unit carbon assimilated
under our experimental conditions. Chlorophyll fluorescence showed no evidence of photoinhibition in any
elevation or treatment category. Earlier soil moisture depletion in heated plots was associated with lower
midday stem water potentials and reduced stomatal conductance in August. Our watering treatments did not
substantially reduce apparent midsummer water stress. Seedlings in ambient temperature plots had higher
assimilation rates in August than those in heated plots, but also greater carbon loss via photorespiration.
Moisture limitation in heated plots in summer interacted with variability in afternoon sun exposure within plots,
and qualitative observations suggested that many seedlings were killed by desiccation and heat girdling at all
elevations. While early snowmelt and moisture availability in heated plots provided a longer growing season,
earlier reduction of soil moisture availability in summer offset this advantage for limber pine seedling carbon
gain.
Stream Temperature Sensitivity to Climate Warming in California’s Sierra Nevada
*Null, S (senull@ucdavis.edu), Center for Watershed Sciences, UC Davis, Davis, CA, USA
Viers, J H (jhviers@ucdavis.edu), Center for Watershed Sciences, UC Davis, Davis, CA, USA
Deas, M (mike.deas@watercourseinc.com), Watercourse Engineering, Inc., Davis, CA, USA
Tanaka, S (stacy.tanaka@watercourseinc.com), Watercourse Engineering, Inc., Davis, CA, USA
Mount, J (mount.jeffrey@gmail.com), Center for Watershed Sciences, UC Davis, Davis, CA, USA
Water temperatures influence the distribution, abundance, and health of aquatic organisms in stream
ecosystems. Improving understanding of climate warming on the thermal regime of rivers will help water
managers better manage instream habitat. This study assesses climate warming impacts on unregulated
stream temperatures in California’s west-slope Sierra Nevada watersheds from the Feather River to the Kern
River. We used unregulated hydrology to isolate climate induced changes from those of water operations and
land use changes. A 21 year timeseries of weekly instream flow estimates from WEAP21, a spatially explicit
rainfall-runoff model were passed to RTEMP, a simplified model based on equilibrium temperature theory, to
estimate stream temperatures using net heat exchange, coarse river channel geometry, and exposure time of
water to atmospheric conditions. Air temperature was uniformly increased by 2 ○C, 4○C, and 6○C as a
sensitivity analysis to bracket the range of likely outcomes for stream temperatures. Other meteorological
conditions, including precipitation, were left unchanged from historical values. Overall, stream temperatures
increased by an average of 1.6○C for each 2○C rise in air temperature, and increased most at middle
elevations. Thermal heterogeneity existed within and between basins (Figure 1). The high watersheds of the
southern Sierra Nevada and the Feather River watershed were less vulnerable to changes in the thermal
regime of rivers from climate warming. Precipitation as rainfall instead of snowfall, and low flow conditions were
two characteristics that drove water temperatures dynamics with climate warming. These results suggest the
thermal regime of rivers will change with climate warming. Viable coldwater habitat will shift to higher
elevations and will likely be reduced in California. Understanding potential changes to stream temperatures
from climate warming will affect how fish and wildlife are managed, and must be incorporated into modeling
studies, restoration assessments, environmental impact statements, and licensing operations of hydropower
facilities to best estimate future conditions and achieve desired outcomes.
Average annual number of weeks stream temperature exceeds 24°C with incremental uniform 2°C air
temperature increases
A subalpine forb's response to natural and experimental climate variation
*Panetta, A M (anne.panetta@gmail.com), Evolution and Ecology, UC Davis, Davis, CA, USA
Harte, J (jharte@berkeley.edu), Energy and Resources Group, UC Berkeley, Berkeley, CA, USA
Stanton, M (mlstanton@ucdavis.edu), Evolution and Ecology, UC Davis, Davis, CA, USA
In light of both molecular and ecological evidence that evolutionary change can happen over short time scales,
many now acknowledge that adaptation could play an important role in species-level responses to climate
change. Working out of the Rocky Mountain Biological Laboratory (RMBL)
(http://www.rmbl.org/rockymountainbiolab/), we test the hypothesis that adaptation plays a role in a montane
forb’s response to both experimental warming and climatic variation across elevations. Our focal organism,
Androsace septentrionalis (Primulaceae, Figure 1), is a locally abundant, short-lived, highly selfing forb that
spans a natural elevation gradient of 2500m to 4811m. Our study sites include six populations, two at high
(3733m), mid (3186m), and low (2933) elevation sites. One of our mid-elevation populations is located in
RMBL’s Warming Meadow, a series of five heated and five control plots. Since 1991, the Warming Meadow
has yielded control and heated plot data on vegetation productivity, phenology, community structure, soil
microclimate, and biogeochemistry. Over the past three years, we have marked, monitored, and collected seed
from A. septentrionalis across both warmed and natural field sites. Here, we highlight how A. septentrionalis’
life history, morphology, and phenology vary across high, mid and low elevation, and we discuss how these
results inform our hypotheses about adaptation in response to experimental warming. We also document the
effects of twenty years of experimental warming on A. septentrionalis abundance, distribution, phenology, and
fitness. Finally, we discuss two ongoing experiments that will help us determine: 1) how selection varies across
heated and control plots and across moisture gradients within each plot: 2) whether or not we can detect
adaptation in response to twenty years of experimental warming: and 3) what roles are played by plastic and
genetic responses to different climatic regimes. By combining the cumulative results of a long-term climate
manipulation experiment with reciprocal transplants and common gardens, we hope to understand the role that
local adaptation plays in species-level responses to global climate change.
Figure 1: Androsace septentrionalis
Science Challenges in Supporting Adaptation Planning in Mountainous Terrain: Lessons from the
NOAA climate assessment to inform the FWS Status Review of the American pika
*Ray, A J (andrea.ray@noaa.gov), Earth System Research Lab, NOAA, Boulder, CO, USA
Barsugli, J J (joseph.barsugli@colorado.edu), CIRES, University of Colorado, Boulder, CO, USA
Eischeid, J (jon.k.eischeid@noaa.gov), CIRES, University of Colorado, Boulder, CO, USA
Wolter, K (klaus.wolter@noaa.gov), CIRES, University of Colorado, Boulder, CO, USA
This presentation will summarize results and some of the scientific challenges that were faced in preparing a
NOAA rapid assessment of climate provided as input to the Fish & Wildlife Service review of the American Pika
to determine if climate change risks warranted listing the species as endangered. NOAA provided FWS with an
assessment of climate observations and projections of change in pika habitat, as a climatological context for
the status review. We provided western regional detail based on existing observations and IPCC model
projections and new findings from interpreting those observations and projections at smaller spatial scales. A
key finding of the report is the large spatial scale of recent and projected warming trends in the West. The 2050
summer temperature projections average about 3°C higher than recent climatology for most of the western
U.S., and for 22 locations representative of pika habitats. Statistically downscaled temperature projections
were used to relate these large-scale trends to habitat elevation bands. Finally, we provided an expert
judgment on the “foreseeable future” for climate for the review. This project required considering the
observations and projections in the context of the heterogeneous terrain that is the habitat for many pika
populations, and interpreting and interpolating information from often distant observing stations, or large-scale
model grid-boxes to make inferences about conditions at finer scales. This presentation will discuss the
findings of the report, and some of the strategies that we adopted for analyzing and presenting climate
projections. The emphasis will be on this real-world example where time and resource constraints were
paramount, as well as the need to use “best available science,” in the context of a formal policy process vs.
time to develop new work. Some of the challenges we faced are applicable to many ecological applications
and for many individual species, including the choice of the sources of climate projections, the interpretation of
downscaled projections, the characterization of uncertainty, and how to combine information from multiple
streams of climate projection information into a more robust inference about the future. While it is easy to be
overwhelmed by uncertainty in a given location, it is important not to lose sight of the "big picture narrative" that
is obtained from climate model projections.
http://www.esrl.noaa.gov/psd/news/2010/020210.html
A Top-down soil moisture and sap flux sampling design to capture the effect of inter-annual climate
variability on ecohydrology in mountain catchments
*Son, K (kson@bren.ucsb.edu), Bren School of Environmental Science and Management, UCSB, Santa
Barbara, CA, USA
Tague, C (ctague@bren.ucsb.edu), Bren School of Environmental Science and Management, UCSB, Santa
Barbara, CA, USA
Soil moisture in mountain catchments is highly spatial heterogeneous due to steep topographic gradients,
complex soil and vegetation patterns and seasonally varying energy and precipitation inputs. In an idealized
setting, a randomized soil moisture sampling design with high spatial frequency can be used to resolve the
spatial heterogeneity of soil moisture at catchment scales. However, this bottom-up approach is constrained by
the feasibility of high frequency measurements particularly in mountain environments with limited accessibility.
Thus, in these mountain environments, an alternative, top-down approach is often needed. In this study, we
propose the top-down approach sampling design of soil moisture and sapflux measurement based on an
ecohydrologic model and clustering analysis. The sampling strategy is explicitly designed to capture the effect
of inter-annual climate variability on ecohydrolgy response of mountain catchments located in King River
Experiment Watersheds, Sierra National Forest. The ecohydrolgic model (RHESSys model) is calibrated with
existing collected data sets including snow depth, soil moisture, sapflux, evapotranspiration from a flux tower
and streamflow. The model is used to generate spatial-temporal patterns of snow accumulation and melt, soil
moisture and transpiration and compute inter-annual mean and coefficient of variation of five hydrologic
similarity indices. Similarity indices are chosen to reflect seasonal trajectories of snowmelt, root-zone soil
moisture storage and evapotranspiration. Clustering analysis, using Partitioning Around Medoid (PAM), is used
to partition the watershed based on these similarity indices. For the Kings River Experimental Watersheds,
clustering distinguished six clusters and a representative plot per cluster. These results were used to identify
additional strategic sampling points within the watershed. For each of these points, we installed soil moisture
sensors (5TE) at the two depths (30m and 90m) and at the five soil pits within a 30m plot. A sapflux sensor at
the average-size white fir tree per plot was also installed. Initial results from monitoring in summer 2010 are
compared with model predictions and used to refine model calibration and uncertainty analysis. Cross-cluster
differences in soil moisture and sap-flow trajectories derived from sampling data will be compared with results
from initial model to assess the validity of the suggested sampling design.
Author(s) (2010), Title, Abstract xxxxx-xxxx presented at 2010 Fall Meeting, AGU, San Francisco, Calif., 13-17
Dec.