WMOD00246

• Contract/Permit #: #95-1
• Applicant: Western Weather Consultants
• Project Name: Vail/Beaver Creek
• Date: 11/1/1995
• Weather Modification - Doc Type: Application

Appendix to Question No.8

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l. Elepbrt Ho. 2. 3. Recipient' 8 Accession NI'.
CSU-FNR-1052-1 ,
4. Ticle 5. Report Date
Ecological Impacts of Snowpack Au~entat1on in the San Juan March 1976
6.
Mountains .of Colorado
7. Author(.) 8. PerforminR Organization Report No.
Harold W. Steinhoff and Jack D. Iv.. (Ed. \
9. P~rforming Organization HalDe and Address Q. Work Unit No.
College of Forestry and Natural Resourc.es
Colorado State University l. Contract or Grant Ho.
Fort Collins, Colorado 80523 14-06-0-7052
2. Sponsoring Agency Name a.ad Address J. Type of Report
Bureau of Reclamation Final Report
BuUding 61, Denver Pedera1 Center 4.
Denver, Colorado B0225
5. Supplementary Note.
This document Tepresent. a coop8ratl~e re.earch effort between Colorado State University. the University. of
Colorado, aDd Fort Lewie College. Thla report super.ade. the prevlou8 Interim Progress Report9 of 1971.
1973, and 1915. -Alao, thia report has been designated as a contribution to the United Nationa Man and the
Bioephere (HAB-6) Program.
6. Abstract
The Collowing conclusions summarize tbe work of 33 scientists from Colorado State University. the Universlty
of Colorado. and Fort 'Levis Cellege vbo studied the effecc. of VaryinR snOWDacK on the ecosystems uf the S~n
Juan Mountains in Colorado from 1970 to 1975. Initiat10n of shoot elongation waa delayed tor plnnts tn the
tundra and foreate .s a readlt of lower teaperature. a..ociated with deeper snowpack. The deIRY WQS mnAt ~p-
parent for herbaceous speciea. such 8S Thurber fe.c.... (Fescuc. thurberl), Whoa. growth points lay tn the
immediate zone of -lover tampetature at ground lavel. The effect on tree. auch .1 Engelmann spruce (~
enaelmanii) and quaking aapen (PopulUS tremulo!des) va. less. The result was a decrease in hlomAsa production
of herbaceous speeie8, but not of trees.or of Ca&bel oak (Quercus gambellii), vfi1cn was fOUIld in a zone that
became snow clear very early. The delay in beginning of growth persisted through the other stages of the
annual cycles of ~st plants but with less magnitude. There seemed universally a COmDenRAtfnn far.~nr which
permitted each species to compress its annual cycle in.years with a shorter grOWing-season caused by greater
depth ~ack. PhytoBociological studies 1n both forests and tundra showed that plant communltTes~ "
arranged along a snow clear date gradient. In the forest. Gambel oak gives way to quaking aspen, then to suh-
alpine fir (~.la8iocarpa). and finally to Engelmann spruce, as the snow'clear date extends later lnto
the year. A noticeable decline in fotest populationa of deer mice (Pero~ySCUS maniculatus) and; to a lesRer
extent, chipmunks (Eutamias spp.) and Microtus spp.. followed ~nters of heavy snowfall. The basic reaSOn
was a dplAv in br@@din2 and in availability of essential foods. No similar effect was found for" "the pock.et
gopher (Tho~mys talpoldes) or mountain toad (Bufo boreas). !It (Cervua canadensis) were almost excluded
from reRlons with more than 70 em of oenetrable Bnow depth. And their travel V88 noticeably restricted at
depths over 40 em. Hovement of elk to higher elevations in spring coincided with the initiation of growth ..f
h&rbaceous nlanta rather-than directly with the recedlng snow line, and adequate calvlnR areas were alwaYR I
present. Plant litter 1n the tundra decreased tn areas 0 deeper .novpack. Local chanKes in the rate of
8011 ero.ion may lncre.le by a factor ot J.U a. a re.ult 0 tbe Rreater area 01 bare 80U left by. "the rltH::re~Mt~
in vegetative cover around snOWbankS. e area 1avo ve 81 IUDa~J. and Chua the tota impact s very sma re2ionall . The long te~ c11mat1c trend since 1930 haa been toward higher temperatures and leg~ precipitat~nl~
with short term fluctuations. of a few years, from relatively dry to' wet modes. No siRnificant increase~ In
silver concentration were detected. because of the ~all amounts added in cloud seed inK and the hl~h back-
2round levels of silver in the target area. No deleterious effects of silver iodide have ~een found at con-
centrations which cou.ld be expected due to C.10UO seea.l.ng. --J
17. Key Words lB. Dlstribution Ststement
alpine tundra. aspen, climate, cloud seeding. Col~rado. Available Protll:
National Technical Information Setvice
ecology, eco8yste~. elk, environmental impact, fescue, Springfield, Virginia 22151
forests, geomorphology, oak, phenology, phytosociology,
productivity. 53n Juan Mountains, stlver iodide. small
nmmmals, snow, spruce. weathef modification.
19. Secuicty Cla8s!f. of this report 20. Security Cla581f~ of this page 2l. No. of pageB 22. Price
t;nclasslf~ed Unclassified 4B9
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