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STATE OF COLORADO • <br />Roy Romar, Governor <br />DEPARTMENT OF NATURAL RESOURCES <br />DIVISION OF WILDLIFE <br />James B. Rueh, Director <br />6080 Broadway <br />Denver, Colorado 80218 <br />Telephone: (303) 297.1792 <br />O \~Jt~ 7°tiL n <br />~,h,~ y~ <br />~ ~~ <br />Dr. H. Bruce Humphries <br />Senior Environmental Engineer <br />Trapper f4ining, Inc. <br />Craig, CO 81626 <br />Dear Bruce: <br />I was pleased to be able <br />wildlife and livestock. <br />and I was impressed with <br />• iiiiiiiiiiiiiiiiiii <br />9ss <br />N. Thompson Hobbs <br />Wildlife Researcher <br />Research Center <br />317 W. Prospect <br />Ft. Collins, CO <br />80526 <br />April 21, 1987 <br />RECE4VE® <br />APR 271987 <br />MINED LAND <br />RECLAMATION DIVISION <br />to see the work you are <br />You have clearly given <br />your thoroughness. <br />doing reclaiming mined lands for <br />the process a great deal of thought, <br />Let me summarize the points I made regarding shrub densities on the area to be reclaimed <br />as elk winter range. Given that a fundamental objective for post-mine use of the <br />area is winter habitat for elk, I believe that area should be capable of supporting <br />some given density of elk for some specific period of time (for example, 30 elk/sq mi. <br />for 3 months). This objective should probably be agreed on in discussions with local <br />OOW people. It can then be translated into a number of elk-days use per unit area, <br />an objective for post-mine carrying capacity. With this objective (or some variation) <br />in mind, it is possible to calculate the total forage required to meet the intake <br />requirements of the hypothetical population by multiplying the daily dry matter intake <br />rate of an individual elk (about 5 kg/d) times the total number of elk-days. Assuming <br />that winter diets of elk on a snowy winter range will contain 50-70% browse, you can <br />determine the mass of shrub production (kg) required to sustain the population. It <br />seems to me that you should be able to convert that mass to stems/ha, or perhaps use <br />it unconverted to justify a given level of shrub production. <br />I think this is a reasonable approach, an approach perfectly analogous to reestab- <br />lishing a given number of AUMs on reclaimed grazing land. Pasture has a value to a <br />rancher independent of the number of cows he may have on it at the moment. So it is <br />for wildlife habitat--it has a value distinct from the animals that happen to be <br />currently using it. <br />I enclosed an example of how to go about calculating carrying capacity for ungulates, <br />In this case, we started with a forage supply and calculated the number of deer it <br />could support. In your case, you will reverse the process, starting with an objec- <br />tive carrying capacity, and calculating back to the forage supply required to sustain <br />it. I also sent several relevant citations. <br />DEPARTMENT OF NATURAL RESOURCES. Clyde O. Martz, Executive Director ~. WILDLIFE COMMISSION, Rebecca L. Frank, Chairman <br />George VanDenBerg, Vice Chairman • Robert L Freidenberger, Secretary • Eldon W. Cooper, Member . William R. Hogberg, Member <br />Dennis Luttrell, Member . Gene 8. Peterson, Member • Larry M. Wrighf. Member <br />