Up, down, and sideways: Complex
responses of plant species to
climate change
Stuart B. Weiss
Creekside Center for Earth Observation
Christopher M. Van de Ven
Dept. of Geol. & Env. Sciences, Stanford University
Setting
Canonical Correspondence Analysis
(CCA)
One of numerous direct gradient analyses
Input matrices of sites/species and
sites/environments
Data from 645 field sites
Creates linear combinations of environmental
variables (axes) that maximally separate sites
and species
Assumes unimodal species distributions
Topography
Geology
Vegetation
Plots
CCA
Current Species’ Distributions
and Environmental Tolerances
Modify Envs. to Simulate Warmer Temps.
CCA
Future Species’
Distributions
Elevation and Geology
Dolomite/
Ridge Crest
1.5
Subalpine
Woodland
1
Pinulon
Dolomite
Tp1000
Axis 2
Juniost
Erigpyg
Cercled
Slope
Tp2000
Pinufle
Artetri
Ribecer
0.5
Geology/
Topographic
Position
Limestone
PinyonJuniper
Woodland
Ephenev
Quartzite
Atrican
0
Elev
Lewipyg
EQsun
SSsun
Hulsalg
-0.5
Pinumon
Grayspi
Holodum
Trifand
Psorarb
Seduros
-1
Draboli
Alpine
Fell-Field
-1.5
Poputre
Desert
Scrub
Lupiteg
Granite
-2
Granite/
Canyon Bottom
-3
-2
-1
0
1
2
3
Axis 1
High/Cool/Wet
Low/Hot/Dry
Elevation/Temp./Precip. Gradient
Desert Scrub (4000-6500ft)
Pinyon-Juniper Woodland (6500-9500ft)
Subalpine Woodland (9500-11,500ft)
Alpine Fell-Fields (11,500-14,246ft)
Axis 3
Axis 4
Evaluation
Previous study 434 calibration sites 216
evaluation sites
22 test species
4 species - Kappa >0.6
8 species - Kappa 0.4-0.6
10 species - Kappa <0.4
Elevation ranges accurately modeled for all
species
Modeling
Climate
Change
Lapse rate: 3ºC/500m
1ºC = 167m = -0.29027 Axis 1 std. devs.
Draba
oligosperma
White Mountain Peak
1ºC
2ºC
Present
Photo © Dean Wm. Taylor, 1972
Pinus
longaeva
Granite
Clastic
Limestone
Dolomite
White Mtn. Pk.
1ºC
6ºC
5ºC
4ºC
3ºC
2ºC
Present
Astragalus
calycosus
Granite
Clastic
Limestone
Dolomite
White Mtn. Pk.
Present
6ºC
5ºC
4ºC
3ºC
2ºC
1ºC
Photo © Br. Alfred Brousseau, St. Mary’s College, 1995
Changes in Area with Increases in Temperature
9000
8000
Hectares
7000
6000
5000
4000
3000
2000
1000
0
0
1
2
3
4
Deg. C above Present Temperature
5
6
Trif_and
Sedu_ros
Pinu_lon
Lewi_pyg
Lewi_gla
Ives_lyc
Hyme_coo
Huls_alg
Erig_pyg
Eric_dis
Eric_cun
Drab_oli
Drab_bre
Astr_cal
Ante_mic
Species Temperature Limits
Extinct after warming 3°C
Extinct after warming 4°C
Extinct after warming 5°C
Extinct after warming 6°C
Antennaria microphylla
Astragalus calycosus
Cryptantha flavoculata
Draba breweri
Draba oligosperma
Ericameria cuneata
Ericameria discoidea
Erigeron pygmaeus
Hulsea algida
Hymenoxis cooperi
Ivesia lycopodioides
Lewisia glandulosa
Lewisia pygmaea
Pinus longaeva
Sedum roseum
Trifolium andersonii
Other Species at Risk
Species not modeled, at higher elevations than our
field sites
Ranunculus eschscholtzii (11,400-14,000ft; 3350-4267m)
Erigeron vagus (>13,000ft; 4000m)
Polemonium chartaceum (>13,000ft; 4000m)
Anelsonia eurycarpa (>13,000ft; 4000m)
E. vagus
P. chartaceum
Photos
© Dean Wm. Taylor
1977, 1975
White Mtn. Peak - 3ºC Temp. Increase
Antennaria microphylla
Draba breweri
Artemisia “arbuscula”
Pinus longaeva*
Pinus flexilis
Erigeron pygmaea*
Additional Considerations
Establishment rates and processes not considered
Dispersal and establishment are not limiting
Interspecies interactions ignored
Some species will migrate faster than others, potentially
inhibiting other species from their upslope migration
Ecological inertia is not considered
Long-lived species may retain lower elevation limits long
after climates change
Upward population movement
Shift of Aspect
Downslope Migration
Millar, Westfall, Delany, 2007
WESTMAP (PRISM)
Conclusions
Climate, topography and geology shape species
distributions, CCA and GIS quantitatively and
maps species-environment relationships
Can model climate change by altering elevation
– first order model
Of the 16 alpine species modeled, 10 are at risk
of extinction with a 3-6ºC increase in
temperature and 4 species at higher elevations
are at greater risk
Conclusions
Of the 16 alpine species modeled, 10 are at risk
of extinction with a 3-6ºC increase in
temperature and 4 species at higher elevations
are at greater risk
With warmer temperatures, all species will
migrate upslope, decreasing areas occupied
Changes in aspect, local downward movements
Geologic barriers prevent upslope migration for
some species
Validate with field observations – “look for the
change” as opposed to “wait for the change.”