Great Basin Tree-Ring Records from Lower-Forest-Border Sites
Franco Biondi and Scotty Strachan
10
The 9 pinyon treering chronologies
(red triangles) were
compared to all the
Pinus monophylla
(blue), and a Juniperus
scopulorum (green)
chronologies in the
International TreeRing Data Bank.
The first principal
component (PC1, 61%
variance for the period
1551-2001) of the 9
pinyon chronologies
had a 0.9 correlation
with PC1 (56% variance
for the 1630-1976 period) of
the 14 ITRDB chronologies.
SSP
PTS639
WLL639
D3
38˚N
N
PAN639
KRW
0
100
120˚W
W
D4
200
118˚W
W
116˚W
W
114˚W
W
MTI
Trees
0
18
33
18
26
28
15
22
38
15
30
30
27
28
328
2
3
0
0
0
0
0
0
0
11
0
0
1
0
17
2
10
17
10
15
14
12
18
15
18
17
16
14
15
193
KRW
WRI
WHR
STC
Based on the 1551-2001 period, there is
a separation between northern (RMS, SSP,
DES) and southern sites (MTI, KRW).
The remaining, central eastern sites
tend to be more similar to the southern
than the northern group.
1900
1950
2000
35˚N
= -0.19
= 0.78
30˚N
25˚N
Cluster Dendrogram
SSP
km
0
DES
1550
1650
1750
1850
20˚N
130˚W
Table 2. Summary of piñon (Pinus monophylla) tree-ring chronologies.
Trees/
LAR/
Long
Lat
First
Last
MSL
Yrs
Cores
Total
(°W)
(°N)
Yr
Yr
-117.78
39.24
1504
2001
498 10/19
330
261/6274
-115.53
40.15
1413
2001
589 16/31
282
38/8729
-117.53
39.06
1300
2002
703
8/15
349
62/5238
-114.21
38.92
1454
2002
549 14/25
345
178/8614
-114.30
39.05
1449
2002
554 13/23
280
127/6447
-115.37
38.95
1400
2002
603 11/13
352
204/4581
-115.39
38.92
1254
2002
749 15/22
358
91/7874
-116.49
37.99
1365
2003
639 13/24
283
300/6790
-115.41
37.63
1301
2003
703 11/18
439
279/7906
MS
0.22
0.10
0.11
0.13
0.19
0.19
0.12
0.20
0.13
St.
Dev.
0.21
0.11
0.13
0.14
0.19
0.19
0.13
0.19
0.14
A1
0.29
0.26
0.47
0.25
0.30
0.23
0.36
0.24
0.26
400
800
125˚W
120˚W
W
Period
N=3
1530-2001
1488-2001
1551-2002
1473-2002
1487-2002
1512-2002
1430-2002
1375-2003
1373-2003
115˚W
110˚W
105˚W
Sample Linear Correlation
-0.7
1950
Year (1551-2001)
DES
RMS
SSP
SCK
STC
WHR
WRI
KRW
MTI
1850
SCK
RMS
Site ID
1800
Period
SS =0.75
1530-2001
1590-2001
1551-2002
1487-2002
1484-2002
1491-2002
1461-2002
1375-2003
1373-2003
MTI
11S, 339570, 4234930
11S, 432939, 4343383
11T, 624945, 4445195
11S, 454450, 4323404
11S, 741500, 4311400
11S, 733700, 4326300
11S, 641450, 4312080
11S, 639900, 4309600
11S, 620500, 3849800
11S, 345750, 4253600
11S, 544400, 4204500
11S, 640600, 4166000
11T, 429000, 4436000
11S, 309200, 4282600
Sections
1750
40˚N
DES
Brawley Peak, NV
Desatoya Mts, NV (DES)
Ruby Mts, NV (RMS)
South Shoshone Peak, NV (SSP)
Great Basin Nat’l Park, NV (SCK)
Great Basin Nat’l Park, NV (STC)
White Pine Range, NV (WHR)
White Pine Range, NV (WRI)
Granite Mts, CA
Lucky Boy Pass, NV
Kawich Range, NV (KRW)
Mt. Irish, NV (MTI)
Fencemaker Pass, NV
Pine Grove Hills
Totals
Cores
1700
0.3
Location (UTM)
1650
From the time-series graph of PC1 scores, the
'Dust Bowl' drought of the 1930s appears to
be exceeded only once (in the 1630s) during
the past 450 years. PC1 of the 9 pinyon
50˚N
chronologies shows excellent agreement
not only with PC1 of the other pinyonjuniper records from the Great Basin
45˚N
but also with hundreds of other ITRDB
chronologies in western North America.
km
36˚N
N
0
Site (ID)
Total
Samples
2
21
33
18
26
28
15
22
38
26
30
30
28
28
345
1600
Year
Table 1. Summary of piñon (Pinus monophylla) field collections.
Elev
(m)
2330
1930
2160
2400
2400
2400
2220
2400
1800
2400
2250
2500
2100
2350
1550
MTI
KRW
_
I t = chronology value at year t = mean annual value
w = ring-width measured at year t in sample i
nt = number of samples at year t
y = curve-fitted value at year t in sample i
(w0.5 – y) = i = index value at year t in sample i
cit = correction factor added to make the overall mean equal to 1
365639 461639
460639 HCR639
MDY639
DCW639
STC
WHR
WRI
SCK
DES
BRY639
PEX639
WRI
+ cit
RMS
SCK
nt
it
N
40˚N
WHR
i =1
)
487639
STC
•
•
•
•
•
•
−y
WHS639
SSP
It =
∑ (w
0.5
PQP639
RMS
i = nt
D2
1
A total of 9 pinyon tree-ring
chronologies were obtained,
out of 14 sites sampled in
2002-2004 (Tables 1 and 2),
using the following formula:
D1
Mean Tree-Ring Index
1
1
1
With funding from the
Paleoclimate Program
of the National Science
Foundation, we are
developing tree-ring
records from lowerforest border species
in the Great Basin.
Ecotonal environments
are ideal places for treering studies of hydroclimatic variability, and
this mountain tree-ring
network updates and
expands prior collections
in the area. While we plan
at least two more seasons
of field work, we present
here the main features of
pinyon (Pinus monophylla)
chronologies developed
to date.
JARAU1
2
Recent mortality
42˚N
N
5
4
0
Climate
Change
-5
5
-10
P-J Expansion
PC1 Score
Reduced Fire
Frequency
0.9
Fire
Suppression
3
0.7
1
0.5
2
Height
Grazing
6
In the Great Basin of North America, long records of climate are important
for fire management, and also for understanding the mechanisms behind
recent expansion of piñon-juniper woodlands. Ecotonal environments
characterized as lower forest border sites are ideal places for tree-ring
studies of hydroclimatic variability. Piñon (Pinus monophylla) trees from
14 sites in the Great Basin have been sampled to develop a network of
moisture-sensitive records spanning the past few centuries. A total of 9
tree-ring chronologies have been developed to date, and the main features
of this mountain tree-ring network are presented. Principal component and
cluster analysis were used to identify bioclimatic zones. For the 1551-2001
period, PC1 accounts for 61% of the variance, and shows a significant
precipitation signal. The 'Dust Bowl' drought of the 1930s appears to have
been exceeded only once (in the 1630s) during the past 450 years.
In the Great Basin, land management agencies
have little to no information on ecosystem
dynamics and their driving forces (such as
wildfire and climate) prior to Euro-American
settlement. While rapid urban and population
growth is increasing the public scrutiny of
land use practices, managers are confronted
with regional environmental changes, clearly
illustrated by the expansion of pinyon-juniper
(P-J) woodlands. The interaction of landscapelevel factors in determining the recent increase
of P-J vegetation is not well understood, even
though it has important implications for fire
management in the Great Basin. In addition,
decadal-scale trends of P-J expansion are
superimposed on shorter pulses of mortality,
such as those seen in the past few years.
PJ Woodland Expansion
Abstract
The main climate signals
(shown by bootstrapped
response functions of
PC1 with monthly mean
temperature and total
precipitation from Nevada
Climate Divisions 2 and 3)
point to cool- and warmseason precipitation.
-0.5
-0.3
-0.1
0.1
0.3
0.5
0.7