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Texas A&M University (2016)

Examining the Impact of Grazing Pressure and Severe Winter Disasters on Livestock Population Dynamics in Mongolian Rangeland

Gao, Weiqian

Titre : Examining the Impact of Grazing Pressure and Severe Winter Disasters on Livestock Population Dynamics in Mongolian Rangeland

Auteur : Gao, Weiqian

Université de soutenance : Texas A&M University

Grade : Master of Science (MS) 2016

Résumé
Rangelands in Mongolia provide biomass for livestock grazing and support the environment that pastoralists have depended on for thousands of years. The quantity and quality of livestock and pasture are critically important to the pastoralists and entire country. Dzud is Mongolian term of severe winter disasters, which can be characterized by heavy snowfall, extreme low temperatures and lack of access to forage and water. The overall research aim is to study the influence of grazing pressure and severe winter disasters on livestock population dynamics on rangeland in Mongolia. The primary objectives were to evaluate Mongolian rangeland grazing pressure and analyze its relationship with livestock losses both spatially and temporally, especially during the dzud periods ; in addition, simulation modeling was used to examine thresholds of forage use, extreme low temperature and snowfall conditions on livestock population dynamics. During the period from 2000 to 2014, the number of hectares delineated as overgrazed was highest in 2014, and was lowest in 2003. Large areas of overgrazing were identified in the central and southern portions of the country. Land areas that were consistently overgrazed (> 10 years) totaled 8.6% of the total land area in Mongolia. The desert steppe zone had the largest amount of area classified as consistently heavily grazed or overgrazed. Climate and human management variables were evaluated to assess their influence on forage availability and livestock population dynamics. Precipitation was the dominant variable influencing forage availability for the majority of the county. Grazing pressure was the dominant variable influencing livestock population dynamics. In the future, the methodologies for grazing pressure assessment could be used in developing guidelines for livestock stocking rates and sustainable pasture management for local communities and the national government. A simulation model was developed to simulate the effects of grazing pressure and winter disasters on livestock population dynamics in Mongolia. The calibration and verification results indicated that the simulation model did a good job in predicting sheep and goat population dynamics in steppe and forest steppe ecological zones, but needs improvement for predicting cattle, horse, and camel population changes in all ecological zones. With additional improvements, the simulation could be useful for government agencies and planning organization in preparing for winter disasters. The prediction of livestock populations could also provide reference data on livestock losses to enhance development of winter disasters response guidelines.

Mots Clés : Grazing Pressure ; Winter Disasters ; Livestock ; Mongolian Rangeland

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