Shifts in alpine and sub-alpine plant species abundances over nearly five decades in a western North America mountain range
White! Mountain !
RESEARCH CENTER"
Christopher W. Kopp and Elsa E. Cleland. Division of Biological Sciences, University of California, San Diego
1993"
Introduction"
Results"
Shifting range distributions observed worldwide provide some of the best
evidence of species responses to increasing global temperatures over the
past century. Many predictions of species range shifts are based on the
climate envelope approach with the null prediction that species ranges will
shift pole-ward and upward in elevation to track suitable climate while
populations at lower elevations and latitudes contract. The Great Basin,
with its numerous isolated mountain ranges, provides an ideal natural
laboratory in which to examine species responses to recent climatic
change. It is projected that boreal habitats in this region may ascend at a
rate as high as 167 m for every 1 ºC increase in mean temperature, such
that a 3 ºC increase in temperature could result in a 66% to 90% loss of
boreal range extent and a 20% to 50% loss of species (1). To examine if
plant communities have responded to recent increases in temperatures, in
2010 we conducted a re-survey of plant species distribution and abundance
in eastern-California’s White Mountains, in areas originally surveyed by
Harold Mooney in 1961.
Between 1961 and 2010 there was a 0.98 °C (F1,42=4.91, p=0.03) increase
in mean growing season temperatures and a 53 mm (F1,47=6.57, p=0.01)
decrease in mean annual precipitation.
Temperature"
Precipitation"
Max 1000 8.0 Mean 6.0 Precipita)on (mm) Temperature in degrees C 10.0 4.0 Min 2.0 800 600 400 0.0 200 -­‐2.0 -­‐4.0 0 1960 1970 1980 1990 2000 2010 1960 1970 1980 Year 1990 2000 2010 Year Figure 1: Mean growing season temperatures (June 1 – October 31) increased 0.98 °C (left) while
mean annual precipitation declined 53 mm (left) during the period between surveys.
Quartzite
Dolomite
Artemisia arbuscula
We A.found
that Artemisia rothrockii increased in abundance at the upper
*
*
*
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reaches of its distribution on granitic substrates between the 1961 and
2000 surveys. In addition, we observed a new elevational record of 4100
m for this species, surpassing the previous record of 3809 m made in 1964
in the
White Mountains. At the same time, we recorded significant
B. Trifolium andersonii
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*
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declines in abundances
in the lower
elevational
ranges of three alpine
cushion plants on granitic substrates: Trifolium andersonii, Phlox
condensata, and Eriogonum ovalifolium.
Line Denstiy/25m
Line Density/25m
40
40
35
35
30
30
25
25
25
20
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20
15
15
15
10
10
10
5
5
5
0
0
0
80
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70
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70
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60
60
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0
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Line
Denstiy/25m
Line
Line DDensity/25m
ensity/25 m C.
Eriogonum
ovalifolium
A.
A.Artemisia
Artemisiaarbuscula
rothrockii
45
40
40
35
35
*
*
**
30
20
10
2900
3050
3200
3350
3500
Line
Density/25m
Line
Line DDenstiy/25m
ensity/25 m D.
condensata
B.B.Phlox
Trifolium
andersonii
Trifolium
andersonii
*
*
*
0
*
45
40
40
35
35
3650
*
*
3800
3950
*
*
**
*
Dolomite
**
45
40
40
35
35
15
15
10
10
55
000
2900
3050
3200
3350
*
3500
3650
*
*
*
3800
3950
70
45
40
60
35
50
30
40
25
30
20
15
20
10
10
5
000
3200
3350
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3650
3800
*
*
*
*
3500
3650
3800
E.C.Koeleria
macrantha
C.
Eriogonum
ovalifolium
Eriogonum
ovalifolium
2900
3050
3200
3350
3950
3950
2900
3050
LineDDensity/25m
Density/25m
Line
Line ensity/25 m Johnnie Lyman!
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70
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000
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3950
*
3500
*
3650
3800
3950
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70
45
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60
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3350
*
Johnnie Lyman!
F.B.Arenaria
kingii
D.
Phlox
Phloxcondensata
condensata
70
80
60
70
3200
30
30
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10
10
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3050
2010
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1961
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LineD
Denstiy/25m
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Denstiy/25m
Line ensity/25 m *
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70
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2010
Quartzite
30
30
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55
000
1961
40
35
30
Granite
40
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E. Koeleria macrantha
3350
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3500
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3650
3650
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3950
Elevation ((m)
Eleva)on m) *
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Figure 2: Distribution and abundance
data in 1961 (blue) and 2010 (red) for
Artemisia rothrockii
(A), Trifolium andersonii (B), Eriogonum ovalifolium (C), and Phlox condensata (D). Significant
differences in abundances between sampling years at individual elevations is denoted by *.
Line Denstiy/25m
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Elevation (m)
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Elevation (m)
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Conclusions"
Historical records indicate that A. rothrockii was found at elevations as
high as 3800 m in the White Mountains in the 1960s (4). Sexually mature
plants of A. rothrockii can now be found as high as 3993 m and a twoyear-old seedling of this species was observed at an elevation of 4102 m in
2012. An increase in abundance from isolated (0.0 plants/m) A. rothrockii
individuals in 1961 at 3650 m to 0.5 plants/m in 2010 shows that this
species is establishing a firm foothold in the alpine. Further, a 2012 revisit
of a photo-point from 1993 shows A. rothrockii has advanced into an area
located at 3593 m in the past 19 years showing that the observed shifts
have been occurring for at least the last two decades.
While A. rothrockii increased in abundance at the upper reaches of its
range and increased its upper range limit on granitic soils, three cushion
plants, E. ovalifolium, P. condensata and T. andersonii experienced
significant declines at the lower portions of their ranges. These shifts
coincide with an overall 0.98 °C increase in mean growing season
temperatures and a 53 mm decrease in mean annual precipitation between
1961 and 2010 at this location. There is growing confidence that warming
of this magnitude is significant enough to cause shifts in plant
communities (5). However, livestock grazing over much of the surveyed
area has been discontinued in the past 20 years and may have contributed
to the observed shifts. Regardless of the cause, continuation of these trends
could result in the transformation of high elevation plant communities in
the White Mountains from alpine to sagebrush steppe.
1. Murphy DD, Weiss SB (1992) in Global Warming and biological diversity, eds Peters L, Lovejoy TE (Hamilton Printing,
Castleton, NY, USA).
2. Mooney HA, Andre GS, Wright RD (1962) Alpine and subalpine vegetation patterns in the White Mountains of California.
American Midland Naturalist 68:257–273.
3. PRISM Climate Group, Oregon State University, http://prism.oregonstate.edu, created 4 Feb 2004.
4. Lloyd RM, Mitchell RS (1973) A flora of the White Mountains, California and Nevada (University of California Press).
5. Rosenzweig C et al. (2008) Attributing physical and biological impacts to anthropogenic climate change. Nature 453:353–357.
Funding was provided by the White Mountain Research Center and the Jean Marie Messier Graduate Student Grant.
F. Arenaria kingii
40
Figure 3: Transect photos from 1993 (left) and 2012 (right) at 3593 m in the White Mountains.
Note the A. rothrockii plants in 2012.
Citations and Acknowledgments"
3050
3050
Elevation
(m)
Eleva)on (m) Elevation(m) (m)
Eleva)on Line Density/25m
We conducted a 49-year re-survey of plant species distribution and
abundance in areas originally surveyed in 1961 (2). Species abundance
data were collected along line transects on granitic, quartzitic, and
dolomitic soils between elevations of 2900 m and 4000 m. To evaluate
how focal species shifted in abundance between 1961 and 2000, and how
these shift varied across elevations and soil-types, z-scores were calculated
for individual species abundances averaged across transects at each
elevation in 2010 and then compared to 1961 data. Growing season
temperature data (June 1 through October 31) collected between 1961 and
2010 at the White Mountain Research Station Barcroft facility (3800 m)
were analyzed to determine changes in mean maximum, minimum and
daily temperatures. Precipitation data compiled from the PRISM Climate
Group (3) were analyzed to determine changes in mean annual
precipitation over the period between surveys.
2012"
1200 12.0 Granite
Methods"
Credit: !
Steven
Travers!
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Elevation (m)
3650
3800
3950