Dynamique spatio-temporelle des paysages forestiers dans le Sud du Sénégal : cas du département de Vélingara

Solly, Boubacar; Diéye, El Hadji Balla; Mballo, Issa; Sy, Oumar; Sané, Tidiane; Thior, Mamadou

doi:10.4000/physio-geo.10634

Cited by 9 publications

(8 citation statements)

References 5 publications

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“…Beyond the classification of the Casamance catchment area upstream of Kolda into seven main land categories (forest, savannah, burnt land, cultivated areas, habitat, plantations and water), the results of the analyses show a significant regression of forest cover in the basin. This study confirms that of Solly et al (2020) who mentioned the combination of several factors such as clearings for agricultural needs, bush fires, population increase, uncontrolled wood cutting, changes in rainfall conditions, among others, as factors responsible for the regression of vegetation cover. Like rainfall, runoff flows alternately decreased during the 1980s and increased from the 2000s onwards, although the trend is not significant.…”

Section: Discussionsupporting

confidence: 90%

“…After identifying the different land use classes, the unsupervised nesting classification was adopted with reference to the work of Andrieu (2008) and Solly et al (2020). The choice of this method was justified by the lack of suitable reference samples for the 1987 image (Masse, 2013).…”

Section: Classification Of Land Use Unitsmentioning

confidence: 99%

“…Generally, areas with no vegetation give a negative value or a value close to zero (meaning no vegetation) and a value close to + 1 (0.8-0.7) represents healthy vegetation (Griffith et al, 2002). In general, values below 0.1 provide information on water, cultivated areas, areas affected by fire and areas with very little vegetation, while values above 0.1 provide information on vegetation cover (Dessay, 2006;Djoufack-Manetsa, 2011;Solly et al, 2020). The closer the value is to 1, the greater the chlorophyll activity and the denser the vegetation.…”

Section: Determination Of Ndvimentioning

confidence: 99%

“…However, it should be noted that the maximum value of chlorophyll activity (+0.70) during the year 1987 could be influenced by the date of the image. Indeed, it should be noted that the vegetation index may be at its maximum at the time of lowest precipitation, although there is a strong correlation between NDVI and rainfall (Dessay, 2006;Solly et al, 2020).…”

Section: Dynamics Of the Normalized Vegetation Index (Ndvi)mentioning

confidence: 99%

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Study of the fluctuation of the NDVI in the Casamance River Basin upstream of Kolda using remote sensing data: what impact on flow?

Faye¹,

Solly²,

Diéye³

2020

Nipp J Environ Sci

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Changes in land use and land cover have attracted considerable scientific interest in recent years because of their marked influence on hydrological cycles. In the tropics, widespread vegetation degradation and changes in land use that occurred from the 1970s onwards have affected the hydrological dynamics of catchments. In this study, land cover changes in the Casamance catchment upstream of Kolda in recent years were analysed and their role in hydrological evolution was estimated. These changes had occurred in environmental conditions between 1987 and 2018. Remote sensing and geographic information system (GIS) techniques were used to monitor changes in the basin as well as changes in NDVI values. Landsat 5 and 8 satellite images were used respectively. The extraction of land cover in the basin was carried out through the application of unsupervised nesting classification processes. The results indicated that a regression of forest cover in the Casamance River Basin upstream of Kolda and the classification of the area into seven main land categories (forest, savannah, slash-and-burn, cultivated areas, habitat, plantations and water) was significant. Like rainfall, the flow rates, which declined during the 1980s, increased from the 2000s onwards, although the trend was not significant. This increase in runoff is the result of vegetation degradation and increased rainfall. The results highlight the importance of integrating land use information into assessments of water availability in a region where water is a strategic resource.

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Section: Discussionsupporting

confidence: 90%

Section: Classification Of Land Use Unitsmentioning

confidence: 99%

Section: Determination Of Ndvimentioning

confidence: 99%

Section: Dynamics Of the Normalized Vegetation Index (Ndvi)mentioning

confidence: 99%

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Study of the fluctuation of the NDVI in the Casamance River Basin upstream of Kolda using remote sensing data: what impact on flow?

Faye¹,

Solly²,

Diéye³

2020

Nipp J Environ Sci

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“…This herbaceous vegetation also provides a reservoir of novel and useful genes, and a considerable source of new diversity [7,8]. Despite their importance, these ecosystems are experiencing increasing degradation due to a variety of factors such as agricultural clearing, overexploitation of woody plants, and climate change [9,10,11]. This strong degradation results in a strong decrease in the diversity of woody species and a modification of the floristic composition of the herbaceous stratum becoming more fragile and very threatened [12,13].…”

Section: Introductionmentioning

confidence: 99%

Influence of Parkia biglobosa (Jacq.) R. Br. Ex G. Don on the Herbaceous Vegetation in the Katouré Valley of the Commune of Nyassia (Basse Casamance-Senegal)

Bassene,

Diedhiou,

Goudiaby

et al. 2023

AJEE

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Aims: Trees outside of protected areas play an important role in providing ecosystem services. They participate in the development of the mat by creating favorable conditions for the development of grasses. The influence of trees on the development and distribution of grasses is not well known. It is in this sense that this study was conducted to determine the effect of Parkia biglobosa cover on the composition, diversity, structure and spatial distribution of herbaceous vegetation. Place and Duration of Study: The study was carried out in the commune of Nyassia in Lower Casamance on a site identified as a Parkia biglobosa park in the Katouré valley in August 2021. Methodology: Floristic surveys were conducted under (R, R/2, R and 2R) and outside the control tree canopy. Results: It was found that the number of species under the tree canopy ranged from 13 to 16 species and was greater than that observed outside the canopy (6 species). Species such as Bracharia deflexa, Cyperus esculentus, Echinochloa colona, Indigofera heudelotii and Pentodon pentandrus were the most frequently encountered in the surveys under the tree canopy (0R, R/2 and R). In contrast, Andropogon gayanus and Bulbostylis capillaris were the most abundant species in the noncanopy surveys. The canopy cover of P. biglobosa, which ranged from 70±17.6 (2R) to 83±19.4 (R/2), was higher than in the uncovered level (54±15.4). Diversity analysis revealed that the canopy surveys 0R (0.80±0.06), R/2 (0.81±0.04) and R (0.77±0.06) were the most diverse. Conclusion: The presence of Parkia biglobosa influenced the presence of herbaceous species and improved habitat conditions.

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Caractérisation de la Dynamique des Peuplements Ligneux du Centre Nationale de Recherches Agronomiques de Bambey (Diourbel/Sénégal)

Diakite,

Djighaly,

Thiam

et al. 2024

ESJ

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Le Sénégal, à l’instar des autres pays sahéliens, est confronté à la dégradation de ses espaces forestiers due à un ensemble de facteurs tels que : les défrichements agricoles, les feux tardifs, l’exploitation anarchique, etc. Ce phénomène est plus accentué dans la région de Diourbel où l’un des très rares poumons verts se trouve dans le site du Centre National de Recherches Agronomiques de Bambey (CNRA). Cette étude avait comme objectifs de caractériser et d’estimer le potentiel des ligneux dans cette formation forestière dans le but de donner formuler des recommandations. Un inventaire systématique sur 103 placettes de 50 X 50 m a été réalisé en 2018. Les paramètres recherchés ont été : la richesse spécifique, la densité du peuplement, la surface terrière, le volume de bois, le couvert aérien, la régénération, la structure horizontale et verticale, les observations sur l’émondage, le vieillissement, etc. Ainsi, 28 espèces appartenants à 13 familles ont été recensées. Les familles des Mimosaceae (28,57%) et des Combretaceae (17,86%) dominent la végétation. Pour les individus adultes, la densité est de 98 individus/ha, dominée par Acacia seyal, tandis que la régénération s’élève à 581 plantules/ha, dominée par Combretum aculeatum. La surface terrière du peuplement est estimée à 2,12 m2/ha, le couvert aérien (3223,08 m2/ha) et le volume (13,83 m3/ha). La distribution du peuplement par classe de diamètre et de hauteur révèle la prédominance de la strate arbustive. Les observations ont montré la présence de pratiques anthropiques qui pourraient contribuer à la régression de la dynamique du peuplement par la diminution du couvert végétal et la disparition de certaines espèces (Deterium microcarpum, Pterocarpus erinaceus et Sterculia setigera) constatée dans cette formation. Ces résultats montrent l’urgence de mettre en place une stratégie de gestion en étroite collaboration avec les communautés pour la conservation et la restauration du couvert végétale de cette formation boisée de 149 ha. Senegal, like other Sahelian countries, is faced with the degradation of its forest areas due to a combination of factors such as agricultural clearing, late fires, uncontrolled logging, etc. This phenomenon is more pronounced in the Diourbel region, where one of the very few green lungs is located on the site of the Centre National de Recherches Agronomiques Bambey (CNRA). This phenomenon is more pronounced in the Diourbel region, where one of the very few green lungs can be found on the site of the “Centre National de Recherches Agronomiques de Bambey” (CNRA). The objectives of this study were to characterize and estimate the potential of woody species in this forest formation, to formulate recommendations. A systematic inventory of 103 50 x 50 m plots was carried out in 2018. The parameters investigated were: species richness, stand density, basal area, wood volume, aerial cover, regeneration, horizontal and vertical structure, observations on pruning, aging, etc. A total of 28 species belonging to 13 families were inventoried. Among these families, Mimosaceae (28,57%) and Combretaceae (17,86%) dominate the vegetation. The density of adult trees is 98 individuals/ha, dominated by Acacia seyal, while regeneration amounts to 581 seedlings/ha, dominated by Combretum aculeatum. The basal area of the stand is estimated at 2.12 m2/ha, the aerial cover (3223.08 m2/ha), and the volume (13.83 m3/ha). The distribution of the stand-by diameter and height class reveals the predominance of the shrub layer. Observations revealed the presence of human practices that could be contributing to the decline in stand dynamics through the reduction in plant cover and the disappearance of certain species (Deterium microcarpum, Pterocarpus erinaceus, and Sterculia setigera) observed in this formation. These results show the urgent need to implement a management strategy in close collaboration with the communities to conserve and restore the plant cover of this 149 ha woodland formation.

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Dynamique spatio-temporelle des paysages forestiers dans le Sud du Sénégal : cas du département de Vélingara

Cited by 9 publications

References 5 publications

Study of the fluctuation of the NDVI in the Casamance River Basin upstream of Kolda using remote sensing data: what impact on flow?

Study of the fluctuation of the NDVI in the Casamance River Basin upstream of Kolda using remote sensing data: what impact on flow?

Influence of Parkia biglobosa (Jacq.) R. Br. Ex G. Don on the Herbaceous Vegetation in the Katouré Valley of the Commune of Nyassia (Basse Casamance-Senegal)

Caractérisation de la Dynamique des Peuplements Ligneux du Centre Nationale de Recherches Agronomiques de Bambey (Diourbel/Sénégal)

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