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Registro Completo |
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Biblioteca(s): |
Embrapa Cerrados; Embrapa Pantanal. |
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Data corrente: |
11/02/1993 |
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Data da última atualização: |
11/02/1993 |
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Autoria: |
KLINK, C. A. |
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Título: |
A comparative study of ecology of native and introduced African grasses of the Brazilian savannas. |
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Ano de publicação: |
1992 |
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Fonte/Imprenta: |
Cambridge, Massachusetts: Harvard University, 1992. |
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Páginas: |
207p. |
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Idioma: |
Inglês |
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Notas: |
PhD. Thesis. |
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Conteúdo: |
African grasses are becoming major invaders of crop fields, degraded rangelands, and natural reserves of the Brasilian savannas (the "cerrados"). The objective of this thesis was to compare ecological characteristics of African and native grasses in an attempt to understand the invasion of cerrados by these introduced species. The hypothesis tested were that African grasses have a higher germination rate, are better competitors in enriched soils, and resist defoliation better than native cerrado grasses. Three sets of experiments were performed: 1) field and laboratory germination; 2) growth and competition in the greenhouse; and 3) field clipping at early and late wet season, and dry season. African grasses germinate faster and more than native species. Seedling mortality is high in African and low in native species. It is suggested that the high seedling mortality of African species is compensated by a large seed production and a high germination rate, and the low seed germination of native species is compensated by a low seedling mortality. The results of the growth and competition experiment were not conclusive. A large variability in biomas production within species exist. The species that invested more in shoots than roots grew more than the species that invested more in roots. It is suggested that the African grass is suppressed more when grown in mixture than in monoculture, while the native species is suppressed more when growing in monoculture. The clipping experiments showed that defoliation decreased plant height in all species. Tillering increased in some African species but not at all in native species. Plant base circumference increased in all species during the dry season clipping, but it was a result of tillering only in the African Hyparrhenia rufa. Late wet season dry season clippings affected plant reproduction in all species that flowered, but not in H. rufa. A time trend analysis revealed that plant height of both African and native species was affected by both clipping and trend of time. Base circumference was affected by treatment only in H. rufa. Tillering in both African and native species showed a significant linear trend of time only. Clipping reduced tillering of the African species Melinis minutiflora. It is concluded that tillering is not necessarily a plant response to defoliation. The only African species resistant to grazing was H. rufa. MenosAfrican grasses are becoming major invaders of crop fields, degraded rangelands, and natural reserves of the Brasilian savannas (the "cerrados"). The objective of this thesis was to compare ecological characteristics of African and native grasses in an attempt to understand the invasion of cerrados by these introduced species. The hypothesis tested were that African grasses have a higher germination rate, are better competitors in enriched soils, and resist defoliation better than native cerrado grasses. Three sets of experiments were performed: 1) field and laboratory germination; 2) growth and competition in the greenhouse; and 3) field clipping at early and late wet season, and dry season. African grasses germinate faster and more than native species. Seedling mortality is high in African and low in native species. It is suggested that the high seedling mortality of African species is compensated by a large seed production and a high germination rate, and the low seed germination of native species is compensated by a low seedling mortality. The results of the growth and competition experiment were not conclusive. A large variability in biomas production within species exist. The species that invested more in shoots than roots grew more than the species that invested more in roots. It is suggested that the African grass is suppressed more when grown in mixture than in monoculture, while the native species is suppressed more when growing in monoculture. The clipping exper... Mostrar Tudo |
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Palavras-Chave: |
Brasil; Distrito Federal; Indigenous organisms; Native grasses; Pasture; Planaltina; Planta nativa; Savana; Savanna. |
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Thesagro: |
Biologia; Cerrado; Ecologia; Ecologia Vegetal; Germinação; Gramínea; Pastagem Nativa. |
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Thesaurus Nal: |
Africa; Brazil; ecology; germination; grasses; plant ecology. |
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Categoria do assunto: |
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Marc: |
LEADER 03414nam a2200397 a 4500
001 1547855
005 1993-02-11
008 1992 bl uuuu m 00u1 u #d
100 1 $aKLINK, C. A.
245 $aA comparative study of ecology of native and introduced African grasses of the Brazilian savannas.
260 $aCambridge, Massachusetts: Harvard University$c1992
300 $a207p.
500 $aPhD. Thesis.
520 $aAfrican grasses are becoming major invaders of crop fields, degraded rangelands, and natural reserves of the Brasilian savannas (the "cerrados"). The objective of this thesis was to compare ecological characteristics of African and native grasses in an attempt to understand the invasion of cerrados by these introduced species. The hypothesis tested were that African grasses have a higher germination rate, are better competitors in enriched soils, and resist defoliation better than native cerrado grasses. Three sets of experiments were performed: 1) field and laboratory germination; 2) growth and competition in the greenhouse; and 3) field clipping at early and late wet season, and dry season. African grasses germinate faster and more than native species. Seedling mortality is high in African and low in native species. It is suggested that the high seedling mortality of African species is compensated by a large seed production and a high germination rate, and the low seed germination of native species is compensated by a low seedling mortality. The results of the growth and competition experiment were not conclusive. A large variability in biomas production within species exist. The species that invested more in shoots than roots grew more than the species that invested more in roots. It is suggested that the African grass is suppressed more when grown in mixture than in monoculture, while the native species is suppressed more when growing in monoculture. The clipping experiments showed that defoliation decreased plant height in all species. Tillering increased in some African species but not at all in native species. Plant base circumference increased in all species during the dry season clipping, but it was a result of tillering only in the African Hyparrhenia rufa. Late wet season dry season clippings affected plant reproduction in all species that flowered, but not in H. rufa. A time trend analysis revealed that plant height of both African and native species was affected by both clipping and trend of time. Base circumference was affected by treatment only in H. rufa. Tillering in both African and native species showed a significant linear trend of time only. Clipping reduced tillering of the African species Melinis minutiflora. It is concluded that tillering is not necessarily a plant response to defoliation. The only African species resistant to grazing was H. rufa.
650 $aAfrica
650 $aBrazil
650 $aecology
650 $agermination
650 $agrasses
650 $aplant ecology
650 $aBiologia
650 $aCerrado
650 $aEcologia
650 $aEcologia Vegetal
650 $aGerminação
650 $aGramínea
650 $aPastagem Nativa
653 $aBrasil
653 $aDistrito Federal
653 $aIndigenous organisms
653 $aNative grasses
653 $aPasture
653 $aPlanaltina
653 $aPlanta nativa
653 $aSavana
653 $aSavanna
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Embrapa Cerrados (CPAC) |
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