Typologie spatiale de la végétation sahélienne en relation avec les indicateurs de dégradation au Burkina Faso

La variation spatiale du couvert vegetal constitue un des determinismes majeurs de la qualite des ecosystemes. Elle influence la physionomie  spatiale de la vegetation ainsi que les mutations des ressources naturelles. Lfobjectif de ce travail est dfexaminer la typologie spatiale de la vegetation sahelienne selon le taux de couverture vegetale en decrivant les glacis selon le stade de degradation a travers une caracterisationfonctionnelle et structurale. La variation spatiale de la couverture vegetale a ete determinee par utilisation dfune image satellitaire de type Modis appuyee dfobservations visuelles et dfinvestigations de terrain. Erdas Imagine 9.2 et ArcGIS.10 ont ete utilises pour la cartographie synchronique de lfindice Normalise Differentiel  de Vegetation (NDVI). Le taux de  couverture vegetale a ete visuellement apprecie sur le terrain. Des relevesphytosociologiques et dendrometriques ont ete faits et des variables  environnementales ont ete examinees et caracterisees. Au terme de cette etude, trois stades de degradation bases sur le taux de couverture  vegetale ont ete definis: le stade tres degrade (NDVI faible et couverture vegetale < 10%), le stade moyennement degrade (NDVI moyen et 10% . couverture vegetale < 30%) et le stade peu degrade (NDVI eleve et couverture vegetale . 30%). Les analyses multivariees montrent une importante dissimilarite entre les stades de degradation des glacis. La caracterisation comparative des variables a revele des differences  significatives. Lfanalyse statistique en composantes principales (ACP) basee sur une approche correlative a permis la mise en evidence des meilleures variables indicatrices de chaque stade de degradation. Cette etude constitue un outil dfaide a la caracterisation des stades de degradation des glacis saheliens, etape importante pour le suivi de ladesertification pour un amenagement durable des ecosystemes.Mots cles: Images satellitaires, couverture vegetale, stades de  degradation, variables indicatrices, amenagement durable, Burkina Faso

Evaluation of phosphorus in forest soils: Comparison of phosphorus uptake, extraction method and soil properties

Phosphorus in soils from plantation of red pine ( Pinus resinosa Ait.) was determined using six extractants: 0.002 N H 2 SO 4 (pH 3.0); 0.025 N HCl+ +0.03 N NH 4 F; 0.5 N NaHCO 3 (pH 8.5); N NH 4 OAc (pH 4.8); anion exchange resin (Dower −2, Cl-form); H 2 O. Correlations of extractable P with Al- and Al-+Fe-P indicated that these fractions are the dominant forms of inorganic P in most of the soils.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43473/1/11104_2005_Article_BF02149737.pd

Access of rural women to forest resources and its impact on rural household welfare in North Central Nigeria

This study examined access of rural women to forest resources and its impact on rural household welfare in North Central Nigeria. Three states out of 6 states in the study area were purposively selected to cover 3 ethnic groups. A state was selected to cover at least one ethnic group. 4 villages were randomly selected in each state to make a total of 12 sample villages. Primary data were collected through structured questionnaire from 20 randomly selected rural women in each sample village to make a total of 240 respondents. Interview schedule was used to get information from 3 key informants in each sample village. The results of the study showed that rural women have restricted access to the exploitation of firewood and forest fruits on communal and family lands in the study area. They however have free and independent access to exploit fodder among the 3 ethnic groups while rural women have free access to exploit snails and mushrooms among the Yoruba ethnic groups in the study area. Chi-square test (p Tenurial rights Rural women Forest resources Rural household North Central Nigeria