http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
A deterministic-empirical microcomputer model based on user inputs of the actual or projected carrying capacity (CC), animal-unit equivalent (AUE), grazing and herd record composition records, a set of coefficients to generate a normal carrying capacity curve (NORCOEF), and a set of coefficients to correct the normal curve for actual growing conditions (CORCOEF) was constructed. The model consists of four submodels: Pasture, Coefficient, Livestock, and Merge Files submodels. Experience is required to run the model because of variation among users in estimating actual CC, NORCOEF, CORCOEF and AUE. Standardization of the AUE and development of a quantitative method to generate a normal CC curve are needed for incorporation into the model. The simplicity of the model allows the user to employ it in an iterative process to converge upon the carrying capacity-stocking rate solution for specific locations. Long term use of the model will generate the records and site specific experience required for accurate assessment of carrying capacity. Two carrying capacity indexes were derived to quantify the portion of the total forage production consumed by grazing livestock. AFV index was calculated from the ratio of forage demand to forage available within a grazing period. The CCC index was derived as the ratio of cumulative forage demand and cumulative forage available. CCC was the preferred index since it estimated the annual or seasonal grazing pressure index (GPI) and it was less variable and more predictable than AFV. CCC may be used to provide an initial estimate of carrying capacity if estimates of above-ground net primary production are available. Annual pastures supported larger CCC than perennial pastures and annual ranges supported greater CCC than cultivated annual pastures. These differences resulted from different management flexibilities and a confounding effect of the number of studies involved in the analyses. On moderately stocked perennial range, approximately 22 % of the primary production was consumed compared to 43 % on heavily stocked ranges. Heavy stocking has the potential danger of resource degradation. CCC was not constant through different precipitation regimes. For different types of climates (wet or dry) the CCC decreased as mean annual precipitation increased, and, within a location, the grazable portion increased as precipitation decreased. Research leading to better estimates of grazing variables such as forage demand and availability, as well as standardization of data reported from grazing studies is of high priority.
Ph. D. in Range Science Texas A & M University 1987
Includes bibliographical references (leaves 76-85).