Climatic Inferences from Dendroecological Reconstructions - Dendroclimatology - page 272

3.0

Blue Mountains, OR

1.5

Wet

0.0

− 1.5

Dry

− 3.0

60

Outbreak

40

20

Endemic

0

1700 1750 1800 1850 1900 1950

4.5

3.0

Southern Rockies, NM

1.5 Wet

0.0

− 1.5

Dry

− 3.0

30

Outbreak

20

10

Endemic

0

1700 1750 1800 1850 1900 1950

3.0

San Juan Mountains, CO

Wet

1.5

0.0

− 1.5

Dry

− 3.0

40

Outbreak

20

Endemic

0

1700 1750 1800 1850 1900 1950

3.0

Sacramento Mountains, NM

1.5

Wet

0.0

− 1.5

Dry

− 3.0

75

Outbreak

50

25

Endemic

0

1700 1750 1800 1850 1900 1950

Year

Fig. 9.6 Composite western spruce budworm histories from four subregions in the western United
States, compared with smoothed (13-year symmetrical weighted low pass filter) summer (July-
August) Palmer Drought Severity Index (PDSI) reconstructions from independent tree-ring width
chronologies (Cook et al. 1999 ) . The smoothed PDSI line in the upper graph is tree-ring recon-
structed and the smoothed dotted line is based on twentieth century instrumental data. Vertical lines
connect the PDSI and budworm axes at the minimum (1 standard deviation) years of the smoothed
PDSI. The Blue Mountains, Oregon, budworm data are partly described in Swetnam et al. ( 1995 ) .
The other budworm datasets are described in Swetnam and Lynch ( 1993 ; southern Rockies, New
Mexico); Ryerson et al. ( 2003 ; San Juan Mountains, Colorado); and Swetnam, Archambault, and
Lynch (unpublished; Sacramento Mountains, New Mexico)