The Interface Between Snowfields and Treeline at Glacier National Park, Montana
Martha Apple, Macy Ricketts, Lindsay Carlson (Biological Sciences, Montana Tech), Nicky Ouellet (Environmental Journalism, University of Montana) ABSTRACT. Snowfields at Glacier National Park will likely retreat or
disappear with climate change. As snowfield edges melt inward in
summer they provide a water-rich microhabitat for alpine plants
capable of growing in the harsh snowfield environment. We
hypothesize that the distribution of alpine plant species and
morphological types will change with the retreat or disappearance of
snowfields. Retreating snowfields will open habitat that may be
colonized by trees, especially since they are currently found close to
most snowfields.
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Width:Length Ratio
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SLA, mm2/mg
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Meters From Snow
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Meters From Snow
Composite Average of Leaf Perimeter Leaf Width Decreased and Length:Width Ratio Increased
with Distance from Snow at the Mt. Clements Moraine
at the Mount Clements Moraine
Composite Average of Leaf Length, mm,
Mount Clements Moraine
20
50
Fig. 1. Composite averages of leaf functional traits changed with distance
from the Mount Clements Moraine snowfield. Specific leaf area (mm2/mg),
circularity, width and width:length ratio decreased. Leaf dry weight,
length, and perimeter increased (n = 696).
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Fig. 2. Sample weight (g/250 ml) varied and the percentage of soil particles
< 1μm decreased with distance from snow at the Mount Clements Moraine
(MCM, n = 3), Mount Clements Long Transect (MCLT, n = 1), Piegan Pass
Snowfield Lateral (PPSL, n = 3), Piegan Pass Snowfield Toe (PPST, n = 3),
Siyeh Pass Snowfield Toe (SPST, n = 1) but not at Siyeh Pass Snowfield
Lateral (SPSL, n = 1).
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Samples with Trees and Mat Forming Plants
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Samples with Trees
Risers
Treads
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Trees Grow on Risers but not Treads of
Patterned Ground
at Piegan and Siyeh Pass
Species Distribution on Treads and Risers of Striped Periglacial
Patterned Ground at the Siyeh Pass Fellfield
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Width (mm)
Length:Width Ratio
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Perimeter, mm
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Width (mm) and Ratio
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Species in Quadrats
Dry Weight (mg)
Circularity and the Width:Length Ratio of Leaves Decreased
with Distance from Snow at the Mt. Clements Moraine
20
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Nearby, on striped periglacial patterned ground:
1) A greater percentage of rare arctic-alpine plants lived on the
stony treads, and;
2) Krummholz trees (Pinus albicaulis and Abies lasiocarpa) were
absent from stony treads but present with mat forming plants
(Dryas octopetala and Salix arctica) on risers of striped
periglacial patterned ground. Association of trees with matforming plants on risers may serve as a leapfrog mechanism
for movement of treeline.
Composite Average of Specific Leaf Area
at the Mount Clements Moraine
Composite Average of
Leaf Dry Weight (mg), MCM
25
Leaf Length, mm
Along permanent geospatially referenced transects established in
2012-14 at the lateral and leading edges of snowfields at Siyeh,
Logan, and Piegan Passes, at Preston Park, and on the Mt. Clements
moraine (the outer, downslope boundary of a vast snowfield), we:
1) Quantified leaf functional traits. Specific leaf area (SLA,
mm2/mg) and circularity were greatest near the snow, while
perimeter, dry weight and area increased with distance from
the snow at the Mt. Clements Moraine (MCM);
2) Classified plants according to the Raunkiaer scheme. Most
were protohemicryptophytes, (overwintering buds at or just
below the ground surface), or geophytes, (overwintering buds
farther beneath the ground), although phanerophytes grew
within 50m and often closer to the snow. Relatively thin-leaved
(and likely less drought tolerant) plants grew near the
snowfield’s edge while cushion plants grew farther from the
snowfields;
3) Found a greater percentage of fine soil particles near snow at
MCM;
4) Grew Penstemon ellipticus, Sibbaldia procumbens, Arenaria
capillaris, Carex sp. and Poa alpina from snowfield seed bank
soil.
Location
Fig. 3. Plant distribution differed on treads and risers of striped periglacial
patterned ground at Siyeh Pass, with more species present or exclusive on
the treads than on the risers (n = 20). Rare species were found only on the
treads. Trees (Pinus albicaulus and Abies lasiocarpa) associated with matforming plants (Dryas octopetala and Salix arctica) were found on risers
but not on treads at Piegan Pass (n = 74) and at Siyeh Pass (n = 74).
Fig. 4. Abies lasiocarpa grows 15-20m from the snowfield on the Mt.
Clements Moraine, on cliffs above the snowfield, and 20-25m from the
Piegan Pass snowfield. Krummholz Pinus albicaulis grow within 50m
of the Piegan Pass snowfield and within 10m of the Preston Park
snowfield’s upper edge. Trees were not found within 50m of the
windy and harsh Siyeh Pass snowfield.
Acknowledgements. Charlie Apple, Jen Asebrook, Jen Hintz, Dawn La Fleur, Craig Lee, Alice Martin, DJ
Moritz, Rene Ouellet, The Montana Tech Plant Ecology Class of 2014, NPS, RM-CESU.