Déterminants de la dynamique de la végétation d'un milieu pâture en région sahélienne du Sénégal / Ousmane NDIAYE (2015) 

Public ISBD Titre : Déterminants de la dynamique de la végétation d'un milieu pâture en région sahélienne du Sénégal Type de document : texte imprimé Auteurs : Ousmane NDIAYE, Auteur Editeur : Dakar : ED-SEV / UCAD Année de publication : 2015 Importance : 133 p. Langues : Français (fre) Catégories : THESES DE DOCTORAT SCIENCES DE LA VIE, DE LA SANTE ET DE L'ENVIRONNEMENT:2015 Mots-clés : SECHERESSE  VEGETATION  COUVERT  COUVERTURE VEGETALE  AZOTE CARBONE  SENEGAL Index. décimale : TED-THESE ECOLE DOCTORALE Résumé : The study of the determinants vegetation dynamics at the Centre de Recherches Zootechniques(CRZ Dahra) revealed a fluctuating contribution of the different morph biological types (orfunctional groups) to the herbaceous cover with a predominance of grasses species (20.7% in 1987 to 68% in 1981 ) and legumes (35.5% in 1975 ; to 75.5 in 1987), of the specific indicators ofquality of plant species, of the gross pastoral value (BPV) (57.8% in 1979 to 76% in 1981) of the herbaceous phytomass (450 kg DM / ha in 1975 to 1880 kg DM / ha in 1988 on average) and the load capacity (0.08 in 1979 to 0.33 UBT / ha / dp in 1988) over the years. The study of the short-term effect of drought on the herbaceous layer has shown a variation of the dry matter plant biomass which experienced a significant decline from the treatments corresponding to 75% water deficit and more for years 2012 and 2013. The floristic richness has not significantly changed according to the different drought treatments for both years. Regarding the evolution of the chemical composition of the soil, the statistical analysis revealed no significant difference in soil carbon content between years 1962 and 2011 at the 0-20 and 20- 40 cm horizons. However, the nitrogen content of the soil was significantly higher in 2011 at the20-40 cm horizon. No difference in carbon and nitrogen contents was observed for the differentsoil types for both horizons between the two years (1962 and 2011), except for the CFC unity atthe 20-40 cm horizon for nitrogen content.Statistical analysis did not detect any significant difference in carbon, nitrogen and C / N ratio ofthe soil at the 0-20 cm horizon between years 1962 and 2011 according to the different types ofland uses. The cropping areas showed the lowest C / N ratio for year 2011. At the 20-40 cmhorizon, the only difference between cropland and pastureland was found in the carboncontent. However, in all types of land use, the carbon and nitrogen contents of the soil measuredin 2001 were higher than those obtained in 1962. PRESIDENT DE JURY : KABORET Yalacé Yamba: Professeur Titulaire à l’EISMV DIRECTEUR DE THESE OU MEMOIRE : DIOP Amadou Tamsir: Directeur de Recherches (LNERV/ISRA) RAPPORTEUR : NDIAYE Paul: Chargé d'Enseignement (FLSH/UCAD)/DIATTA Malaïni: Maître de Recherches (CNRF/ISRA) MEMBRE : AKPO Léonard Elie: Professeur titulaire (FST/UCAD) CO-DIRECTEUR : NDIAYE Aminata: Professeur titulaire (FLSH/UCAD) DATE DE SOUTENANCE : 11/07/2015 PAYS : Sénégal Permalink : https://cid.eismv.org/pmb/opac_css/index.php?lvl=notice_display&id=4732 Déterminants de la dynamique de la végétation d'un milieu pâture en région sahélienne du Sénégal [texte imprimé] / Ousmane NDIAYE, Auteur . - Dakar : ED-SEV / UCAD, 2015 . - 133 p. Langues : Français (fre) Catégories : THESES DE DOCTORAT SCIENCES DE LA VIE, DE LA SANTE ET DE L'ENVIRONNEMENT:2015 Mots-clés : SECHERESSE  VEGETATION  COUVERT  COUVERTURE VEGETALE  AZOTE CARBONE  SENEGAL Index. décimale : TED-THESE ECOLE DOCTORALE Résumé : The study of the determinants vegetation dynamics at the Centre de Recherches Zootechniques(CRZ Dahra) revealed a fluctuating contribution of the different morph biological types (orfunctional groups) to the herbaceous cover with a predominance of grasses species (20.7% in 1987 to 68% in 1981 ) and legumes (35.5% in 1975 ; to 75.5 in 1987), of the specific indicators ofquality of plant species, of the gross pastoral value (BPV) (57.8% in 1979 to 76% in 1981) of the herbaceous phytomass (450 kg DM / ha in 1975 to 1880 kg DM / ha in 1988 on average) and the load capacity (0.08 in 1979 to 0.33 UBT / ha / dp in 1988) over the years. The study of the short-term effect of drought on the herbaceous layer has shown a variation of the dry matter plant biomass which experienced a significant decline from the treatments corresponding to 75% water deficit and more for years 2012 and 2013. The floristic richness has not significantly changed according to the different drought treatments for both years. Regarding the evolution of the chemical composition of the soil, the statistical analysis revealed no significant difference in soil carbon content between years 1962 and 2011 at the 0-20 and 20- 40 cm horizons. However, the nitrogen content of the soil was significantly higher in 2011 at the20-40 cm horizon. No difference in carbon and nitrogen contents was observed for the differentsoil types for both horizons between the two years (1962 and 2011), except for the CFC unity atthe 20-40 cm horizon for nitrogen content.Statistical analysis did not detect any significant difference in carbon, nitrogen and C / N ratio ofthe soil at the 0-20 cm horizon between years 1962 and 2011 according to the different types ofland uses. The cropping areas showed the lowest C / N ratio for year 2011. At the 20-40 cmhorizon, the only difference between cropland and pastureland was found in the carboncontent. However, in all types of land use, the carbon and nitrogen contents of the soil measuredin 2001 were higher than those obtained in 1962. PRESIDENT DE JURY : KABORET Yalacé Yamba: Professeur Titulaire à l’EISMV DIRECTEUR DE THESE OU MEMOIRE : DIOP Amadou Tamsir: Directeur de Recherches (LNERV/ISRA) RAPPORTEUR : NDIAYE Paul: Chargé d'Enseignement (FLSH/UCAD)/DIATTA Malaïni: Maître de Recherches (CNRF/ISRA) MEMBRE : AKPO Léonard Elie: Professeur titulaire (FST/UCAD) CO-DIRECTEUR : NDIAYE Aminata: Professeur titulaire (FLSH/UCAD) DATE DE SOUTENANCE : 11/07/2015 PAYS : Sénégal Permalink : https://cid.eismv.org/pmb/opac_css/index.php?lvl=notice_display&id=4732

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
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