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Silene acaulis
Geum rossii
Andrea Dixon
Winter Ecology
Spring 2009
Mountain Research Station, University of Colorado, Boulder
Does differential snowpack affect alpine plant
community composition?
1.
Snowpack varies across
the landscape due to
local variables such as
topography, wind and
climatic factors
2.
Snowmelt is controlled
by the quality of snow,
the thickness of the
snowpack, air
temperatures and solar
radiation
3.
Snowpack, and thus
snowmelt, affects
growing season length
Photo: Williams, et al.
LESS SNOWPACK = LONGER GROWING SEASON
Focus on 2 studies:



RESPONSES OF SNOWBED PLANT-SPECIES TO CHANGES IN GROWING-SEASON
LENGTH (Galen & Stanton, 995)
SMALL-SCALE PLANT SPECIES DISTRIBUTION IN SNOWBEDS AND ITS SENSITIVITY
TO CLIMATE CHANGE (Schob, et al. 2009)
RESPONSES OF SNOWBED PLANT-SPECIES TO CHANGES IN GROWING-SEASON
LENGTH (GALEN & STANTON, 995)
Leaf expansion occurs at snowmelt -w/in 6days
Leaf
expansion
occurs at
snowmelt w/in 3 days
Leaf expansion occurs at
snowmelt -w/in 9 days
These 2 plants had a 2-3 fold
increase in cover with long
growing seasons. These plants
also have longer periods of
shoot growth.
RESPONSES OF SNOWBED PLANT-SPECIES TO CHANGES IN GROWING-SEASON
LENGTH (GALEN & STANTON, 995)

Growing season length had the
most pronounced affect on
those plants that begin their
leaf expansion (growth) at
snowmelt.
R. adoneus
S. procumbens

Plants that delay their leaf
expansion by 1-2 weeks, were
not as affected by changes in
growing season length.
T. parryi
G. rossii
SMALL-SCALE PLANT SPECIES DISTRIBUTION IN SNOWBEDS AND ITS
SENSITIVITY TO CLIMATE CHANGE (SCHOB, ET AL. 2009)
5 Categories of Plants
1. Dominants (make up most of the vegetation) – Increased with later
snowmelt dates
2. Subordinate species (making up less of the % cover than dominants):
2a. Indifferents to snowmelt dates – no change to later snowmelt dates
2b. Snowbed specialists – increased significantly with later snowmelt
dates (delayed leaf expansion plants)
2c. Avoiders of late-snowmelt sites – significantly decreased with later
snowmelt dates (immediate leaf expansion plants)
3. Transients – almost completely disappeared with later snowmelt dates
Fig. 1 Number of species
along the snowmelt
gradient for the five
categories :





SNOWMELT DATE
Dominants
D (-□-)
Indifferents to snowmelt
dates
I (- · -■- · -)
Snowbed specialists
S (- -○- -)
Avoiders of late-snowmelt
sites
A (- · · -+- · · -)
Transients
T (- -×- -).
SMALL-SCALE PLANT SPECIES DISTRIBUTION IN SNOWBEDS AND ITS
SENSITIVITY TO CLIMATE CHANGE (SCHOB, ET AL. 2009)
Plant species richness was reduced by approximately 50% in
snowbeds with late melt dates.
Total cover by vascular species was not reduced- only the number
of species making up the cover.

Plants have species specific responses to snowpack
variation (Galen & Stanton, 1995)

Longer growing season will lead to loss of species that
area adapted to and thrive on a short growing season
(late snowmelt) as their habitat disappears (Schob et al., 2008)

Growing season length had a significant impact on the
plants that have leaf growth that is synchronized with
snowmelt (snowbed specialists) (Galen & Stanton, 1995)

This becomes a disadvantage during years of late
snowmelt (Galen & Stanton, 1995)

If temps increase and snowmelt occurs earlier,
plants that avoid late snowmelt sites will increase
their area of cover, comprising a greater
percentage of the cover species as their suitable
habitat increases in area (Schob et al., 2008)

Transient plants may increase in amount of cover,
as well as number of overall species of transients
with longer growing season- this needs more
study (Schob et al., 2008)
Galen, C. and M. L. Stanton, 1995. Responses of snowbed-plant species to changes in growing-season
length. Ecology 76:1546-1557.
Monson, R.K., D.L. Lipson, S.P. Burns, A.A. Turnipseed, A.C. Delaney, M.W. Williams and S.K. Schmidt,
2006. Winter forest soil respiration controlled by climate and microbial community composition. Nature
439:711-714.
Raible, C.C., C Casty, J. Luterbacher, A. Pauling, J. Esper, D.C. Frank, U. Buntagen, A.C. Roesch, P Tschuck,
M. Wild, P.L. Vidale and C Schar, 2006. Climate variability- observations, reconstructions and model
simulations for the Antlantic-European and Alpine region from 1500-2100 AD. Climate Change 79:9-29.
Schob C. , P.M. Kammer, P. Choler, H. Veit, 2008. Small-scale plant species distribution in snowbeds and its
sensitivity to climate change. Plant Ecology 200:91-104
Seastedt, T.R. and L. Vacarro, 2001. Plant species richness, productivity, and nitrogen and phosphorus
limitations across a snowpack gradient in Alpine Tundra, Colorado, USA. Arctic, Antarctic and Alpine
Research 33:100-106.
Question: Does differential snowpack affect alpine
plant community composition?
Conclusion:


Plants responses to snowpack (growing season length)
are species specific based on their adaptations to the
environment- such as how/when they begin leaf
expansion
Warming and cooling trends seen in the Alpine will
lead to decreases in some plants and increases in
others, which could lead to plant community
compositions that are ‘novel’ for the Alpine