Reconstructing a Past Climate Using Current Multi-species' Climate Spaces
U53A-0708
Robert D. Westfall and Constance I. Millar
Sierra Nevada Research Center, USDA Forest Service, Pacific Southwest Research Station, Albany, California, USA
ABSTRACT
Species range polygons were intersected with the nine PRISM climate grids
Whitebark Pine Range: Sierran and Eastern Sierran
PRISM Grids -- Annual Maximum Temperature ( oC x 100)
We present an analysis of a ghost forest on WhiteWing Mt at 3000 m in the eastern Sierra Nevada, southeast of Yosemite NP.
Killed by a volcanic eruption about 650 years ago, the deadwood on WhiteWing dates by standard tree-ring analysis to 8001330 CE, during the Medieval Warm Anomaly. Individual stems have been identified by wood anatomical characteristics as
Pinus albicualis, P. monticola, P. jeffreyi, P. contorta, P. lambertiana, and Tsuga mertensiana. With the exception of P.
albicualis, which is currently in krummholz form at this elevation, the other species are 200 m or more lower in elevation. One,
P. lambertiana, is west of the Sierran crest and 600 m lower in elevation. Assuming that climatic conditions on Whitewing
during this period were mutually compatible with all species, we reconstruct this climate by the intersection of the current
climatic spaces of these species. We did this by first generating individual species' ranges in the Sierran ecoregions through
selecting vegetation GIS polygons from the California Gap Analysis database (UCSB) that contain the individual species.
Climatic spaces for each species were generated by the GIS intersection of its polygons with 4 km gridded polygons from
PRISM climatic estimates (OSU); this was done for annual, January, and July maximum and minimum temperature, and
precipitation, merged together for each species. Climatic intersections of the species were generated from the misclassified
polygons of a discriminant analysis of species by the climatic data. The average data from these misclassified polygons
suggest that the climate on WhiteWing during the existence of this forest community was 230 mm, 1oC, and 3oC greater than
present in precipitation, and maximum and minimum temperature, respectively.
Lake Tahoe
Sweetwater
Mts
Wassuck
Range
Mono Lk
Glass Mt
White Mts
Intersection of range polygons and PRISM grids
SETTING
Data from intersected species range polygons with the 9 climate grids were
merged together among 5 species (lodgepole pine was omitted). These species
climate data had considerable overlap. To maximize species differences, we
analyzed the data by discriminant analysis, classifying the data by species.
WhiteWing Mountain in the eastern Sierra Nevada, south of June
Lake, CA. Forms the southern boundary of the upper Glass Creek
Watershed. Elevation - 3000 m.
Tri-variate Climate Spaces: Sugar Pine (blue) & Whitebark Pine (red)
Deadwood Species
Deadwood is scattered on ridge top and slopes, dated to the
period, 800-1345 CE. Killed by a volcanic eruption 1345 CE (see
Millar, et al., Poster U53A-0707)
20 Whitebark Pine - krummholz
20 W White Pine - ↓250 m
9 Lodgepole Pine - ↓250 m
Wood identified to: whitebark pine (Pinus albicaulis), western white
pine (P. monticola), sugar pine ), P. lambertiana), lodgepole pine
(P. contorta), Jeffery pine (P. jefferii), and mountain hemlock
(Tsuga mertensiana).
7 Jeffrey Pine ↓500 m
4 Mt Hemlock ↓250 m
3 Sugar Pine ↓600 m & W SN
Excepting whitebark pine, which now grows in krummolz
(prostrate) form the other species grow up to 600 m lower in
elevation; sugar pine is west of the Sierran Crest and does not
overlap whitebark pine in habitats
Sugar pine in its
typical westside
habit
METHODS
Question: If these species were cohorts, the climate must
have been compatible to all -- i.e., fundamental niche
spaces had overlapped (Jackson & Overpeck 200)
Data Sources
• Range Maps: California Gap Analysis Project (UCSB) Polygons selected from codominant species in primary-to-secondary cover types; Sierra Nevada and Eastern
Sierra Jepson eco-regions
http://www.biogeog.ucsb.edu/projects/gap/gap_home.html
• Climate: 4 km PRISM Gridded Data (Spatial Climate Analysis Service). Minimum
and maximum temperature, precipitation (30 yr averages); Annual, January, and July
http://www.ocs.orst.edu/prism/
Literature cited:
From Thompson et al. 1999
Jackson, S. T., and J. T. Overpeck. 2000. Responses of plant populations and
communities to environmental changes of the late Quaternary. Paleobiology 25:194220.
Millar, C. I., R. D. Westfall, D. L. Delany, J. C. King, and L. J. Graumlich. 2004.
Response of subalpine conifers in the Sierra Nevada, California, USA, to
twentieth-century warming and decadal climate variability. Arctic, Antarctic,
& Alpine Research 36:181-200.
Thompson, R.S., Anderson, K.H. and Bartlein, P.J. 1999. Atlas of Relations Between
Climatic Parameters and Distributions of Important Trees and Shrubs in North
America. U.S. Geological Survey Professional Paper 1650 A&B;
http://pubs.usgs.gov/pp/1999/p1650-a/.
RESULTS
The first two canonical vectors
accounted for 97% of the
differences among species, with
the first vector showing the
greatest differences among
species (see table to right).
Temperature was correlated with
scores on this first vector, though
July precipitation was negatively
associated; precipitation
(excepting July, was associated
with the second vector.
Canonical analysis
Can 1
Can 2
Correlation
0.76
0.45
Percent
81
16
Correlations
Max Temp
0.95
-0.17
Min Temp
0.95
-0.05
Ppt
0.18
0.92
Jan Tmax
0.92
-0.29
Jul Tmax
0.89
0.13
Jan Tmin
0.90
0.24
Jul Tmin
0.80
0.06
Jan Ppt
0.22
0.92
Jul Ppt
-0.58
0.07
The greatest difference among species was between whitebark (pial) and sugar
(pila) pines (see figure to right). We computed mean climatic data for
misclassified observations and compared these with the PRISM estimates for
WhiteWing (see
Mean
Whitewing
Difference
table to right).
Max Temp
13.30
12.80
0.50
These data
Min Temp
-0.07
-3.00
2.93
indicate greater
Precip
1134.65
881.00
253.65
precipitation,
Jan Max T
4.74
4.00
0.74
mainly in winter,
23.99
24.40
-0.41
and much higher Jul Max T
Jan Min T
-6.01
-10.60
4.59
winter minimum
Jul Min T
8.06
5.60
2.46
temperatures.
Jan Precip
203.69
147.00
56.69
Maximum
Jul Precip
11.85
11.00
0.85
temperatures and
Note: temperatures are oC and precipitation in mm
July precipitation
changed little. Temperatures and precipitation over the past century are trending
in this same direction.
From Millar et al. 2004