Daniel E. Winkler , Travis E. Huxman , and Gaku Kudo

Morphological and physiological compensation promote
climate-induced invasions above and below treeline
Daniel E. Winkler1, Travis E. Huxman1, and Gaku Kudo2
Ecology & Evolutionary Biology, University of California, Irvine, [email protected]
Environmental Earth Science, Hokkaido University
Environmental drivers
Physiological variability and stress
Predicting vegetation change associated with plant traits has been a challenge of our
last decade1.
Each site exhibited distinct physiological profiles, likely related to different ecological
filters in place at each site:
The bamboo Sasa kurilensis has expanded its distribution in Japan up to 47% over the
past 30 years and reduced snow-meadow plant community richness by 75%2
tStomatal conductance to water
vapor were lowest in alpine
and highest in forest, with the
subalpine site spanning lower and
higher elevation profiles
tAlpine and subalpine chlorophyll
ranges were lower and similar
relative to values measured in the
shaded forest site
Deciphering biological patterns evidenced in Sasa kurilensis’ expanded range is key to
understanding the underlying mechanisms that explain invasive species success3.
Our research examines the interaction of global change and species
invasions. Specifically, we aim to:
1. Reveal the biological mechanisms that correspond to climate-induced
invasions of dwarf bamboo both above and below treeline
2. Determine environmental drivers promoting dwarf bamboo expansion
Changes in winter precipitation and the timing
of snowmelt have allowed dwarf bamboo to
expand both above and below treeline and
invade alpine and subalpine communities2, 5
Above photo: bamboo being released fromsnowpack.
16−2289 μmol Daisetsuzan National Park
Hokkaido, Japan
ation gradient
3 sites along a 600 m elevation
Each site, tagged:
10 current year culms
10 culms >1 yearr old
mperature an
Daily measurements of temperature
total daily precipitation
Plant growth measurements:
weekly- height, number off branches,
number of leaves
9−931 μmol
Relative water content of leaves (an indicator of water
stress) varied between sites and with time:
Growth and allocation
trend throughout the growing season while alpine
leaves followed the opposite trend
tHeight decreased with elevation
t5IFOVNCFSPGCSBODIFTQFSDVMN increased with elevation
only slight variations between sites
25−2370 μmol
Above graph: Daily air temperature (º C) measured at a height of 50cm, highlighting variability in temperatures for for alpine (red line),
subalpine (blue line), and forest (green line) sites. Total daily precipitation (mm) plotted as bars.
There were distinct patterns in growth and
allocation in culms (stems) between sites:
Dwarf bamboo (S. kurilensis):
tcommon in snowy regions of Hokkaido, Japan
textensive rhizome networks & dense patches
toutcompetes natives & dominates large areas4
Physiological measurements:
ce, chlorophyll content
weekly- leaf conductance,
bimonthly- leaf relative water content
Above graphs: Smoothed frequency histograms for stomatal conductance
to water vapor (left) and leaf chlorophyll content (right).
Left graph: leaf-level relative water content (%) in mid-July (day 196), early August
(day 210), and mid-August (day 225) measured on 20 randomly selected culms in the
forest (green), subalpine (blue), and alpine (red) sites. Bars represent site means with
standard error.
Conclusions & future directions
There were distinct patterns in growth and
allocation between current year culms and
culms that were >1 year old:
Different allocation strategies were
employed by bamboo across the
elevation gradient
tCurrent year culms increased in height
faster than older culms
their first year of growth, indicating
potential light limitations in the forest
whereas subalpine and alpine
individuals exhibited varied strategies.
leaves during their first year of growth
compared to subsequent years.
Allocation strategies and physiological
metrics are consistent with shifts in
light to water stress as important
constraints across the elevations
Right graphs: Time series changes in culm height of current year
culms (top left) and culms >1 year old (top right), the number of
branches of current year culms (middle left) and culms >1 year old
(middle right), and the number of leaves of current year culms
(bottom left) and culms >1 year old (bottom right). Shaded areas
are smoothed standard errors. Note differences in scale.
Left photo: subalpine site with
bamboo encroaching. Below
illustration: cartoon showing
belowground growth habit
of bamboo.
dictive models using environmental
Future- We plan to build predictive
data collected at each of the sites
Once completed, this research
may be able to explain the
biological mechanisms that
allow for invasive species
success and may also be
used to accurately predict
future invasions
Acknowledgements &
Above photos: Alpine site with Mt.
Asahidake in background (top),
subalpine site (middle), and forest site
(bottom). PAR values indicate light
regimes as ranges of photosynthetically
active radition (PAR) at each site. Right
map: Topographic map with field sites
and elevations. Inset shows location of
Daisetsuzan National Park in Japan.
This material is based upon work supported by the
National Science Foundation under Grant No.
IIA-1414603 and the Japan Society for the Promotion
of Science Summer Program. Citations: 1. Lavorel and
Garnier (2002). 2. Kudo et al. (2011). 3. Hobbs (2000). 4.
Oshima (1961). 5. Takada et al. (2012).