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Publication Date
1981
Description
Studies were conducted on a desert grassland range in southern New Mexico for 3 years to determine relative consumption rates of the main herbivores utilizing these range areas. Consumption of some groups (cattle, pronghorn antelope, and rabbits) was determined from direct estimates of intake/individual, and density was determined from censusing procedures or known stock rates. Consumption by other groups (birds, rodents, and invertebrates) was determined from census information relating to age structure of the population and metabolic rate. Consumption by all herbivores averaged less than 5 % of the above-ground net primary productivity for the 3 years of the study. Highest consumption rates among the herbivore groups were for cattle, which consumed an average of 4.3 g/m2 during the study. Consumption by rodents was fairly high during the first year of the study when rodent densities were high but declined during the second and third years in response to declines in rodent densities. In contrast, invertebrate consumption was highest during the third year of the study and actually exceeded that of rodents. Precipitation was favorable during the third year of the study and was reflected by the high above-ground net primary productivity that year. Apparently, invertebrate populations responded more quickly to favorable plant growth than rodent populations did. Consumption rates of pronghorn antelope, rabbits, and birds were relatively small. Rabbit consumption was nearly constant during the study period. Density of breeding bird populations was fairly low, although large buildups of migrant bird populations occurred late in the third year of the study. Energy flow to the herbivore populations was also small compared with above-ground net primary productivity. Total energy transfer to herbivores was only 24.3 kilocalories (kcal)/m2 in contrast to 593 kcal/m2 calculated for above-ground net primary productivity. Large herbivores, including pronghorn antelope and cattle, contributed most of the energy transferred dudng herbivory, followed by small mammals, invertebrates, birds, and rabbits. From the standpoint of range productivity, it appears that a relatively small portion of energy fixed by plants is harvested by man in the form of animal products. There appears to be a large, untapped source of energy on rangelands that has the potential to be converted to food for a hungry world. How best to make use of this resource and still maintain stable ecosystems is a challenge facing range researchers and users.
Citation
Pieper, R D., "Consumption Rates and Desert Grassland Herbivores" (1981). IGC Proceedings (1981-2023). 15.
(URL: https://uknowledge.uky.edu/igc/1981/section7/15)
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Consumption Rates and Desert Grassland Herbivores
Studies were conducted on a desert grassland range in southern New Mexico for 3 years to determine relative consumption rates of the main herbivores utilizing these range areas. Consumption of some groups (cattle, pronghorn antelope, and rabbits) was determined from direct estimates of intake/individual, and density was determined from censusing procedures or known stock rates. Consumption by other groups (birds, rodents, and invertebrates) was determined from census information relating to age structure of the population and metabolic rate. Consumption by all herbivores averaged less than 5 % of the above-ground net primary productivity for the 3 years of the study. Highest consumption rates among the herbivore groups were for cattle, which consumed an average of 4.3 g/m2 during the study. Consumption by rodents was fairly high during the first year of the study when rodent densities were high but declined during the second and third years in response to declines in rodent densities. In contrast, invertebrate consumption was highest during the third year of the study and actually exceeded that of rodents. Precipitation was favorable during the third year of the study and was reflected by the high above-ground net primary productivity that year. Apparently, invertebrate populations responded more quickly to favorable plant growth than rodent populations did. Consumption rates of pronghorn antelope, rabbits, and birds were relatively small. Rabbit consumption was nearly constant during the study period. Density of breeding bird populations was fairly low, although large buildups of migrant bird populations occurred late in the third year of the study. Energy flow to the herbivore populations was also small compared with above-ground net primary productivity. Total energy transfer to herbivores was only 24.3 kilocalories (kcal)/m2 in contrast to 593 kcal/m2 calculated for above-ground net primary productivity. Large herbivores, including pronghorn antelope and cattle, contributed most of the energy transferred dudng herbivory, followed by small mammals, invertebrates, birds, and rabbits. From the standpoint of range productivity, it appears that a relatively small portion of energy fixed by plants is harvested by man in the form of animal products. There appears to be a large, untapped source of energy on rangelands that has the potential to be converted to food for a hungry world. How best to make use of this resource and still maintain stable ecosystems is a challenge facing range researchers and users.
