TREE-RING INDICES OF RAINFALL, TEMPERATURE, AND RIVER FLOW 
explanation of these characteristics has not yet been 
developed. 
LINES OF FUTURE DEVELOPMENT 
It is probable that the contributions of tree-ring 
analysis to meteorological and hydrological knowledge 
have only just begun to be manifest. Advances will 
depend on two related developments: the construction 
- of growth indices for new areas and, in areas already 
studied, the replacement or amplification of indices by 
others of greater fidelity to the limiting climatic vari- 
able. The profound importance of the latter property 
of ring chronologies cannot be overemphasized. 
Reconnaissance has shown that rainfall chronologies 
of good sensitivity may be found in selected trees in the 
headwaters areas of the Missouri, Snake, and other 
major rivers of the western United States; indices for 
these basins comparable to that already developed for 
the Colorado River Basin are now being constructed. 
Potential sources of rainfall chronologies appear to 
exist in the mid-latitude Andes Mountains, the Medi- 
terranean area, the northwest provinces of India, and 
elsewhere. The vast Siberian Arctic is, as far as is known, 
totally untouched as a source of temperature chro- 
nologies. 
The refinement of tree-ring data is primarily related 
to chronologies in semiarid regions. Even the most 
elaborate index of this type thus far available, that for 
the Colorado River Basin developed in 1945, is subject 
to considerable improvement. The last century of this 
index is based on some 100 Douglas fir trees from 24 
stations within the basin, supplemented by two indices 
in other species from seven and four stations respec- 
tively; earlier portions of the index are progressively 
weaker, the main index at A.D. 1500, for example, repre- 
senting 10 stations and 34 trees, supplemented by one 
minor index for one station. Field work since 1945 
has shown that at least 50 stations within this basin 
can yield sensitive records from 500 to 800 years old, 
in both Douglas fir and pinyon pine, from which it is 
possible to derive indices of substantially higher fidelity 
to rainfall and runoff, particularly m the earlier cen- 
turies. Such an extension is now in progress. 
As the world map of significant tree-ring chronologies 
of rainfall or temperature becomes more complete, some 
estimate may become possible of the large-scale fluc- 
tuations in the weather year by year for many centuries. 
Long-term statistical frequencies found in the climatic 
records in trees of any area should have greater signi- 
ficance in the light of similar data from many other 
areas. The application of such knowledge to practical 
problems in such domains as reclamation, conservation, 
and water power would seem to be immediate. Of great 
potential importance is the possible bearing of climatic 
research in dendrochronology on the problems of long- 
range climatic forecasting. 
REFERENCES 
1. Aanpstap, S., ‘Die Jahresbestimmung der Kiefer und 
die Zeitbestimmungen Alterer Gebiude in Solér im éstli- 
chen Norwegen.”’ Nyt Mag. Naturv., 78: 201-268 (1988). 
2. Antrvs, E., “Die Jahresringe der Holzgewichse und die 
Bedeutung derselben als klimatischer Indikator.” Progr. 
Rei bot., 5: 285-386 (1917). 
1029 
3. —— “Rainfall and Tree Growth in the Great Basin.” 
Spec. Publ. Amer. geogr. Soc., No. 21: Carneg. Instn. 
Wash. Publ. 469 (1988). 
4. pp Gurr, G., “Geochronologia Suecica Principles.” K. 
svenska VetenskAkad. Handl., Ser. 3, Bd. 18, No. 6 (1940). 
5. Doueuass, A. H., “Climatic Cycles and Tree-Growth.”’ 
Carneg. Instn. Wash. Publ. 289: I, 127 pp. (1919); II, 
166 pp. (1928); III, 171 pp. (1936). 
6. —— “‘The Secret of the Southwest Solved by Talkative 
Tree Rings.” Nat. geogr. Mag., 56: 736-770 (1929). 
7. —— “Estimated Ring Chronology, 150-1934 A. D.” Tree- 
Ring Bull., 6: 39 (1940). 
“Notes on the Technique of Tree-Ring Analysis.”’ 
Tree-Ring Bull., 7: 2-8 (1940); 7: 28-34 (1941); 8: 10-16 
(1941); 10: 2-8 (19438); 10: 10-16 (1943). 
9. ——“Precision of Ring Dating in Tree-Ring Chronologies.”? 
Bull. Univ. Ariz., Vol. 17, No. 3 (1946). 
10. Erpem, P., “Uber Schwankungen im Dickenwachstum der 
Fichte (Picea Abies) in Selbu, Norwegen.” Nyt Mag. 
Naturv., 83: 145-189 (1943). 
11. Exuunp, B., “‘Ett forsék att numeriskt faststilla klimatets 
inflytande p& tallens och granens radietillvaxt.” Norr- 
lands SkogsvF'érb. Tidskr., 3: 193-226 (1944). 
12. Ertanpsson, 8., Dendrochronological Studies. Stockholms 
Hégskolas Geokronol. Inst., Data 23, 1936. 
13. Grppines, J. L., Jr., ‘“Dendrochronology in Northern 
Alaska.” Bull. Univ. Ariz., Vol. 12, No. 4: Publ. Univ. 
Alaska No. 4 (1941). See also ‘“‘Chronology of the Kobuk- 
Kotzebue Sites.”’ Tree-Ring Bull., 14: 26-32 (1948). 
14. —— ‘Mackenzie River Delta Chronology.” Tree-Ring 
Bull., 13: 26-29 (1947). 
15. Guocx, W. §., “Growth Rings and Climate.” Bot. Rev., 
7: 649-713 (1941). 
16. Harpman, G., and Ret, O. E., “Relationship between 
Tree Growth and Stream Runoff in the Truckee River 
Basin, California-Nevada.”’ Bull. Nev. agric. Exp. Sta., 
No. 141 (1936). 
17. Huser, B., und Hotpuerpe, W., ‘“Jahrringchronologische 
Untersuchungen an Ho6lzern der bronzezeitlichen Was- 
serburg Buchau am Federsee.’’? Ber. disch. bot. Ges., 
50: 261-283 (1942). 
18. Husticn, I., ‘“‘The Scotch Pine in Northernmost Finland 
and Its Dependence on the Climate in the Last Decades.” 
Acta bot. fenn., 42 (1948). 
19. Kapreyn,J.C., Tree Growth and Meteorological Factors.” 
Rec. Trav. bot. néerland., 11: 71-93 (1914). 
20. Kern, F. P., ‘‘Climatie Cycles in Eastern Oregon as In- 
dicated by Tree-Rings.”? Mon. Wea. Rev. Wash., 69: 
175-188 (1937). 
21. Lyon, C. J., ““‘Water Supply and the Gro ;th Rates of Coni- 
‘ers around Boston.” Hcology, 24: 329-344 (1943). 
‘Hemlock Chronology in New England.” Tree-Rking 
Bull., 13: 2-4 (1946). 
23. Orvine, A., “Arringanalyser p& Gran og Furu.’’ Medd. 
norske Skogsforséksv., 7: 105-354 (1941). 
24. Scuutman, E., ‘‘Centuries-Long Tree Indices of Precipita- 
tion in the Southwest.’’ Bull. Amer. meteor. Soc., 23: 
I, 148-161; II, 204-217 (1942). 
25. ——“Tree-Ring Hydrology of the Colorado River Basin.” 
Bull. Univ. Ariz., Vol. 16, No. 4 (1945). 
26. —— “Dendrochronologies in Southwestern Canada.” T’ree- 
Ring Bull., 13: 10-24 (1947). 
27. —— “‘Tree-Ring Hydrology in Southern California.”’ Bull. 
Univ. Ariz., Vol. 18, No. 3 (1947). 
28. —— (Reports on Climatic-Archaeological Indices in the 
Southwest.) V'ree-Ring Bull., 12: 18-24 (1946); 14: 2-8 
(1947) ; 14: 18-24 (1948); 15: 2-14 (1948); 15: 24-32 (1949) ; 
16: 10-14 (1949). 
