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The near absence of competitive plant activity, in a desolate
environment, is certainly a factor in the successful growth of the bristlecone
pine, but equally important perhaps is the facility of the pines to remain
rooted in blocks of dolomitic substrate. The roots of these trees dig deep into
the joints and cracks of the supportive dolomite and anchor the pines to the
ground during times of heavy winter windblow. Other types of pines found on
White Mountain--limber, pinyon and foxtail pines--tend to grow on lower, more
sheltered ground, and in areas where soil horizons are fairly well developed in
a relatively loose substrate. Rarely are these other pines found on the bald
dolomites that seem to be the home ground of thc bristlecone. At many points,
distinctions of species are so clear that geologic mapping could almost be done
on the basis of tree identification.
On a recent trip to White Mountain, I was
fortunate enough to see a golden eagle perched on the top branch of a twisted
and ancient bristlecone. Somehow the two old men of the mountain seemed to go
together.
SELECTED
REFERENCES
- Billings. C. B., 1950, Vegetation and plant
growth as affected by chemically altered rocks in the western Great Basin:
Ecology. v. 31, p. 62-74.
- California Division of Mines and Geology.
1958. Proposal may withdraw land from bristlecone pine forest: MINERAL
INFORMATION SERVICE. v. 11. no. 10. p. 10-12.
- Munns, E. N., 1938. The distribution of the
important forest trees of the United States: United States Department of
Agriculture Miscellaneous Publication 287. 118 p.
- Schulman, E. l958. Bristlecone pine, oldest
known living thing: National Geographic Magazine, v. 113. p. 355-372.
- Wright, R. D. and Mooney, H. A. 1965.
Substrate-oriented distribution of bristlecone pine in the White Mountains of
California: American Midland Naturalist. v. 73, p. 257-2$4.
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| trees are
found along north-facing mountain slopes at elevations of 9,500 to 12,000 feet;
precipitation on these slopes is slight and generally ranges from 9 to 14
inches per year; temperatures arc cold and annual averages are 30 to 35 degrees
F.; winter winds can be fierce and are frequently laden with heavy loads of ice
and snow. Perhaps one of the most unusual aspects of the bristlecone pine
habitat however, relates to conditions of the soil and rock on which the tree
grows and survives. |
Soil studies
and geologic mapping show that almost all stands of the bristlecone pine are
restricted to areas of exposed dolomite. Few bristlecones are found on
exposures of quartzite, serpentine and granitic rocks. Unlike other pines along
the slopes and ridges of White Mountain, the bristlecone seems to grow best on
dolomite rock materials having a high alkalinity (pH 7.9 to 8.4) and a low soil
nutrient yield. These incredibly durable trees survive in areas where little
other vegetation seems to endure. |