WMOD00290 ‎(2)‎

• Project Name: The Medicine Bow Ecology Project
• Title: The Potential Sensitivity of Various Ecosystem Components to Winter Precipitation Management in the Medicine Bow Mountains, Wyoming
• Prepared For: Bureau of Reclaimation
• Date: 2/28/1975
• State: WY
• Weather Modification - Doc Type: Report

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silver iodide treatment, of course, must be applied in some manner
,ather than seeding, but meaningful data can be obtained for some
org~ln'isms, in particular small plants and micro-organisms. Analysis
of variance can be used to evaluate treatment effect with a certain
degree of confidence. This approach was used in the Medicine Bow
Project for one vegetation study and two studies on silver iodide
toxicity.
Before-and-af ter mon i tor i ng approach
This approach is desirable because no'control is necessary and
actual cloud seeding provides .the snow treatment. It is a desirable
phase of any impact study and has been an important approach for the
Medicine Bow Projec~. Considerable baseline information 'is included
in this report.
The disadvantages-with the before-and-after approach are that the
impact is not known until it's happened over a large area,' which seems
I ike a poor management approach, and there. is often the question about
whether the changes that occurred after the cloud seeding were in

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. fact caused by the seed i ng or some other natura I phenomenon. We can
expect this problem in the case of winter precipitation management
because the secondar~ ~col09ical effects are not likely t~ be observed
for several years, if .not decades. The ecosystems are already adapted
to considerable year to year fluctuations in snowfall, so changes will
probably result from a modified mean annual snowfall or a modified
sequence of heavy and light snowfall years. The accumulation of Ag
compounds to toxic levels is also likely to be slow.
The system ana.lysis approach
Invariably an evaluation of impact calls for an analysis of the
ecosystems in which a new management program is planned. These eco-
systems are sufficiently complex that rarely is a total system analysis
possible. Experience gained from the International Biol.ogical Program
suggests that such an effort is also expensive. However, to one degree
or another, using various tools and with variable success, ecologists
for y'ears have worked toward gaining a better understanding' of ecosystem
structure and function. Usually the focus has 'been on sub-systems for

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