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Registro Completo |
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Biblioteca(s): |
Embrapa Pantanal. |
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Data corrente: |
14/04/1999 |
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Data da última atualização: |
14/04/1999 |
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Autoria: |
ABDEL-RAZIK, M.; ABDEL-AZIZ, M.; AYYAD, M. |
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Afiliação: |
Botany Department, Faculty of Science, University of Alexandria, Egypt. |
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Título: |
Multivariate analysis of vegetational variation in different habitats at Omayed, Egypt. |
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Ano de publicação: |
1984 |
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Fonte/Imprenta: |
Vegetatio, v.57, n.2/3, p.167-175, 1984. |
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Idioma: |
Inglês |
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Conteúdo: |
The application of indicator species analysis has proved useful in classifying stands into groupings coinciding with topographic variations. 41 indicator pseudo-species are identified in the vegetation along a phytosociological gradient: some are characteristics of specific habitats, and the others indicate transition between groups of habitats. The use of qualitative estimations (transformed density records) in multivariate analysis in the present study indicates that they may be more preferable than quantitative estimations, because of their easy and fast recording in the field, and the less comprehensive computation, while yielding precise results. The X-axis of the reciprocal averaging ordination is related to the salinity and fertility gradients, while the Y-axis reflects soil texture. The phytosociological gradients of the canonical variate axes reflect essentially contrasts between groups of species, each correlated with one or the other of the environmental gradients. Comparing the results obtained by the two ordination methods (reciprocal averaging and canonical variates) we find that the first method detects the overall phytosociological changes along strong environmental gradients which would be helpful in studying large surveys. On the other hand, the second technique, which is mainly predictive, is more sensitive to changes within both the phytosociological and environmental gradients and can detect the impact of these changes on the overall variance of each gradient. MenosThe application of indicator species analysis has proved useful in classifying stands into groupings coinciding with topographic variations. 41 indicator pseudo-species are identified in the vegetation along a phytosociological gradient: some are characteristics of specific habitats, and the others indicate transition between groups of habitats. The use of qualitative estimations (transformed density records) in multivariate analysis in the present study indicates that they may be more preferable than quantitative estimations, because of their easy and fast recording in the field, and the less comprehensive computation, while yielding precise results. The X-axis of the reciprocal averaging ordination is related to the salinity and fertility gradients, while the Y-axis reflects soil texture. The phytosociological gradients of the canonical variate axes reflect essentially contrasts between groups of species, each correlated with one or the other of the environmental gradients. Comparing the results obtained by the two ordination methods (reciprocal averaging and canonical variates) we find that the first method detects the overall phytosociological changes along strong environmental gradients which would be helpful in studying large surveys. On the other hand, the second technique, which is mainly predictive, is more sensitive to changes within both the phytosociological and environmental gradients and can detect the impact of these changes on the overall variance of each gra... Mostrar Tudo |
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Palavras-Chave: |
Analise multivariada; Egito. |
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Thesagro: |
Habitat; Vegetação. |
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Thesaurus Nal: |
Egypt; multivariate analysis; vegetation. |
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Categoria do assunto: |
-- |
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Marc: |
LEADER 02113naa a2200229 a 4500
001 1795223
005 1999-04-14
008 1984 bl --- 0-- u #d
100 1 $aABDEL-RAZIK, M.
245 $aMultivariate analysis of vegetational variation in different habitats at Omayed, Egypt.
260 $c1984
520 $aThe application of indicator species analysis has proved useful in classifying stands into groupings coinciding with topographic variations. 41 indicator pseudo-species are identified in the vegetation along a phytosociological gradient: some are characteristics of specific habitats, and the others indicate transition between groups of habitats. The use of qualitative estimations (transformed density records) in multivariate analysis in the present study indicates that they may be more preferable than quantitative estimations, because of their easy and fast recording in the field, and the less comprehensive computation, while yielding precise results. The X-axis of the reciprocal averaging ordination is related to the salinity and fertility gradients, while the Y-axis reflects soil texture. The phytosociological gradients of the canonical variate axes reflect essentially contrasts between groups of species, each correlated with one or the other of the environmental gradients. Comparing the results obtained by the two ordination methods (reciprocal averaging and canonical variates) we find that the first method detects the overall phytosociological changes along strong environmental gradients which would be helpful in studying large surveys. On the other hand, the second technique, which is mainly predictive, is more sensitive to changes within both the phytosociological and environmental gradients and can detect the impact of these changes on the overall variance of each gradient.
650 $aEgypt
650 $amultivariate analysis
650 $avegetation
650 $aHabitat
650 $aVegetação
653 $aAnalise multivariada
653 $aEgito
700 1 $aABDEL-AZIZ, M.
700 1 $aAYYAD, M.
773 $tVegetatio$gv.57, n.2/3, p.167-175, 1984.
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Registro original: |
Embrapa Pantanal (CPAP) |
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