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Registro Completo |
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Biblioteca(s): |
Embrapa Pantanal. |
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Data corrente: |
02/08/1995 |
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Data da última atualização: |
10/09/2010 |
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Autoria: |
ODUM, E. P.; CONNELL, C. E.; DAVENPORT, L. B. |
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Título: |
Population energy flow of three primary consumer components of old-field ecosystems. |
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Ano de publicação: |
1962 |
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Fonte/Imprenta: |
Ecology, v.43, n.1, p.88-96, Winter, 1962. |
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Idioma: |
Inglês |
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Conteúdo: |
Population energy flow of 3 major primary consumer groupos living in the early stages of old-field succession on the AEC Savannah River area was considered in relation to the net primary production of the ecosystem. The animal population studied were: (1) herbivorous orthoptera (Chiefly the grasshoppers Melanoplus femurrubrum and M. biliteratus and the cricket Oecanthus nigricornis); (2) winter resistant Savannah sparrows (Passerculus sandwichensis); and (3) old-field mice (Peromyscus polionotus). The orthoptera comprised a large portion of the grazers while the 2 vertebrate populations were the chief granivores of the ecosystem. Both production (population growth) and respairation were calculated by integrating field and laboratory measurements to obtain an estimate of the total annual energy flow (in kilocalories/M2) for each population group in nature. Measurements of food assimilated (intake minus excretory loss) by animals in large cages or enclosures provided a more satisfactory basis for estimating the population respiratory energy flow than did measurement of oxygen consumption of animals confined in conventional respirometers. At average density levels recorded on the study areas energy flow in kilocalories/M2/year was estimated to be 3.6 for the sparrows, 6.7 for the mice and 25.6 for the orthoptera. values 2 or 2 1/2 times higher densities found in the most favorable areas. Only a small proportion on the total energy utilization for a season or annual cycle was channelled into production, about 2% for mice and 15% for grasshoppers; most of the energy flow was required to maintain the standing crop (i.e. was respiration). The birds, although not breeding in area, have a small "production" in the form of premigratory fat deposits. The ratio of production calories to the average standing crop calories (i.e., the annual turnover rate in terms of energy) ranged from 2.5 to 4.9 in 3 mouse populations; the lowest ratio occurred in an unfavorable habitat where the population failed the following year. The two granivore population together were estimated to require 10 a 50% of the annual seed crop, depending on animal density and seed production. In contrast, the herbivorous orthoptera were estimated to require only 2-7% of energy available in the annual crop of above-
ground vegetation; however, to obtain this energy, 2-3 times as much food must be eaten since the assimilation efficiency of grazing insects is low. Even so it was estimated that the orthoptera together with all other insects would rarely eat as much as 20% of the net production of vegetation. It is concluded that food is more likely to be limiting to granivores than to foliage-consuming herbivores in the old-field ecosystem, although more data are needed as to the portion of vegetation which is actually available as food to grasshoppers and other insects. In terms of density and energy flow, granivores in terrestrial ecosystem appear to be intermediate in trophic position between grazing herbivores and carnivores. MenosPopulation energy flow of 3 major primary consumer groupos living in the early stages of old-field succession on the AEC Savannah River area was considered in relation to the net primary production of the ecosystem. The animal population studied were: (1) herbivorous orthoptera (Chiefly the grasshoppers Melanoplus femurrubrum and M. biliteratus and the cricket Oecanthus nigricornis); (2) winter resistant Savannah sparrows (Passerculus sandwichensis); and (3) old-field mice (Peromyscus polionotus). The orthoptera comprised a large portion of the grazers while the 2 vertebrate populations were the chief granivores of the ecosystem. Both production (population growth) and respairation were calculated by integrating field and laboratory measurements to obtain an estimate of the total annual energy flow (in kilocalories/M2) for each population group in nature. Measurements of food assimilated (intake minus excretory loss) by animals in large cages or enclosures provided a more satisfactory basis for estimating the population respiratory energy flow than did measurement of oxygen consumption of animals confined in conventional respirometers. At average density levels recorded on the study areas energy flow in kilocalories/M2/year was estimated to be 3.6 for the sparrows, 6.7 for the mice and 25.6 for the orthoptera. values 2 or 2 1/2 times higher densities found in the most favorable areas. Only a small proportion on the total energy utilization for a season or annual cycle was ch... Mostrar Tudo |
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Palavras-Chave: |
Ecosystem; Energia de populacao; Fluxo; Population energy flow. |
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Thesagro: |
Ecossistema. |
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Categoria do assunto: |
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Marc: |
LEADER 03600naa a2200205 a 4500
001 1785256
005 2010-09-10
008 1962 bl --- 0-- u #d
100 1 $aODUM, E. P.
245 $aPopulation energy flow of three primary consumer components of old-field ecosystems.
260 $c1962
520 $aPopulation energy flow of 3 major primary consumer groupos living in the early stages of old-field succession on the AEC Savannah River area was considered in relation to the net primary production of the ecosystem. The animal population studied were: (1) herbivorous orthoptera (Chiefly the grasshoppers Melanoplus femurrubrum and M. biliteratus and the cricket Oecanthus nigricornis); (2) winter resistant Savannah sparrows (Passerculus sandwichensis); and (3) old-field mice (Peromyscus polionotus). The orthoptera comprised a large portion of the grazers while the 2 vertebrate populations were the chief granivores of the ecosystem. Both production (population growth) and respairation were calculated by integrating field and laboratory measurements to obtain an estimate of the total annual energy flow (in kilocalories/M2) for each population group in nature. Measurements of food assimilated (intake minus excretory loss) by animals in large cages or enclosures provided a more satisfactory basis for estimating the population respiratory energy flow than did measurement of oxygen consumption of animals confined in conventional respirometers. At average density levels recorded on the study areas energy flow in kilocalories/M2/year was estimated to be 3.6 for the sparrows, 6.7 for the mice and 25.6 for the orthoptera. values 2 or 2 1/2 times higher densities found in the most favorable areas. Only a small proportion on the total energy utilization for a season or annual cycle was channelled into production, about 2% for mice and 15% for grasshoppers; most of the energy flow was required to maintain the standing crop (i.e. was respiration). The birds, although not breeding in area, have a small "production" in the form of premigratory fat deposits. The ratio of production calories to the average standing crop calories (i.e., the annual turnover rate in terms of energy) ranged from 2.5 to 4.9 in 3 mouse populations; the lowest ratio occurred in an unfavorable habitat where the population failed the following year. The two granivore population together were estimated to require 10 a 50% of the annual seed crop, depending on animal density and seed production. In contrast, the herbivorous orthoptera were estimated to require only 2-7% of energy available in the annual crop of above- ground vegetation; however, to obtain this energy, 2-3 times as much food must be eaten since the assimilation efficiency of grazing insects is low. Even so it was estimated that the orthoptera together with all other insects would rarely eat as much as 20% of the net production of vegetation. It is concluded that food is more likely to be limiting to granivores than to foliage-consuming herbivores in the old-field ecosystem, although more data are needed as to the portion of vegetation which is actually available as food to grasshoppers and other insects. In terms of density and energy flow, granivores in terrestrial ecosystem appear to be intermediate in trophic position between grazing herbivores and carnivores.
650 $aEcossistema
653 $aEcosystem
653 $aEnergia de populacao
653 $aFluxo
653 $aPopulation energy flow
700 1 $aCONNELL, C. E.
700 1 $aDAVENPORT, L. B.
773 $tEcology$gv.43, n.1, p.88-96, Winter, 1962.
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Registro original: |
Embrapa Pantanal (CPAP) |
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