This study describes the floristic composition and structure of a woody stand in the Senegalese Sahel, paying particular attention to the edaphic factors of its floristic composition. A stratified inventory considerin...This study describes the floristic composition and structure of a woody stand in the Senegalese Sahel, paying particular attention to the edaphic factors of its floristic composition. A stratified inventory considering the different relief units was adopted. Woody vegetation was surveyed using a dendrometric approach. The results obtained show that the flora is dominated by a few species adapted to drought, such as Balanites aegyptiaca (L.) Del., Calotropis procera Ait. and Boscia senegalensis (Pers.). The distribution of this flora and the structure of the ligneous plants are linked to the topography. In the lowlands, the flora is more diversified and the ligneous plants reach their optimum level of development compared with the higher relief areas. In the lowlands, there are a few woody species which, in the past, were indicative of better climatic conditions. These are Anogeissus leiocarpus (DC.), Commiphora africana (A. Rich.), Feretia apodanthera Del., Loeseneriella africana (A. Smith), Mitragyna inermis (Willd.) and Sclerocarya birrea (A. Rich). It is important that their reintroduction into reforestation projects takes account of their edaphic preference.展开更多
The combined effects of climate change and human pressure have led to the progressive degradation of natural resources in semi-arid regions. Woody taxa in these regions play an important role in the functioning and se...The combined effects of climate change and human pressure have led to the progressive degradation of natural resources in semi-arid regions. Woody taxa in these regions play an important role in the functioning and services provided by semi-arid savannah by serving as forage for both domestic and non-domestic grazers. Maintaining the functioning of semi-arid savannas thus requires understanding the dynamics of these communities of woody taxa and their responses to exogenous forces, such as climate. To better understand the dynamics of woody taxa in semi-arid environments we collected dendrometric characteristics from five field sites along an environmental gradient in the Ferlo region of central Senegal. Density and basal area were found to be greater in the northern part of the zone, contrasted with the distance between individuals and crown cover, which is greater in the southern part of the zone. Stand structure estimated from the distribution according to height and diameter at breast height shows a preponderance of individuals in the shrub layer, although with a significant representation of the tree layer in southern Ferlo. Stand regeneration was better in the south and less effective in the north. There was a trend towards the rejuvenation of populations belonging to the dominant species. There were only three species for which degradation was not apparent (Balanites aegyptiaca, Acacia raddiana and Dalbergia melanoxylon), all of which have important ethnobotanical uses, suggesting that human use of taxa can play an important role in preventing degradation. Three distinct groups of woody taxa were found to correspond to gradients of precipitation, topography, and human land use pressure. Our results suggest an important role in the management and reintroduction of woody species in the Sahel and the regulation of pastoral techniques necessary for the rehabilitation of the agro-pastoral zone of Senegal.展开更多
The objective of this study is to analyze the dendrochronological potential of two Sahelian species (<i><span style="font-family:Verdana;">B. senegalensis</span></i><span style=&qu...The objective of this study is to analyze the dendrochronological potential of two Sahelian species (<i><span style="font-family:Verdana;">B. senegalensis</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">S. birrea</span></i><span style="font-family:Verdana;">) and to evaluate the rela</span><span style="font-family:Verdana;">tionships between their growth rings and the climate. The study was con</span><span style="font-family:Verdana;">ducted in 2016 in the Ferlo area of Senegal. The biological material consists of wood slices, taken from the trunks of these adult woody species at 0.30 m and 1.30 m from the ground after they have been felled. The technique used to examine the slices consists in identifying their rings, establishing their structures, inter-dating them and studying the relationship between the identified rings and climatic factors. The results showed that the species had thin, clear, highly visible and sharp rings. The limit of growth is marked by a line of parenchyma. Intradatation series carried out on the chronologies made it possible to estimate the ages of the individuals, which vary from 10 to 38 years for </span><i><span style="font-family:Verdana;">B. senegalensis</span></i><span style="font-family:Verdana;"> and from 29 to 50 years for </span><i><span style="font-family:Verdana;">S. birrea</span></i><span style="font-family:Verdana;">. Their average growth </span><span style="font-family:Verdana;">rates are estimated at 0.906 mm/year and 0.89 mm/year respectively. The </span><span style="font-family:Verdana;">chronological sequences are 29 years (1987-2016) for </span><i><span style="font-family:Verdana;">B. senegalensis</span></i><span style="font-family:Verdana;"> and 38 years (1964-2012) for </span><i><span style="font-family:Verdana;">S. birrea</span></i><span style="font-family:Verdana;">. The results revealed that there is no significant correlation between the growth chronologies of </span><i><span style="font-family:Verdana;">B. senegalensis</span></i><span style="font-family:Verdana;"> and the </span><span style="font-family:Verdana;">climatic regressors (temperature and precipitation). In contrast, the ring-</span><span style="font-family:Verdana;">climate relationship shows that in </span><i><span style="font-family:Verdana;">S. birrea</span></i><span style="font-family:Verdana;"> winter precipitation positively influences ring growth while temperature has no effect on ring growth in this species. This study provides a better understanding of the response of forest ecosystems to possible climate change, particularly in the current context of sustainable forest management.</span>展开更多
The aim of this study was to evaluate orthodontic treatment needs among Ferlo scholars. The design of the study was descriptive and transversal. For Inclusion criteria, children must live in Widou or live around Widou...The aim of this study was to evaluate orthodontic treatment needs among Ferlo scholars. The design of the study was descriptive and transversal. For Inclusion criteria, children must live in Widou or live around Widou’s school at least 6 km, be students at primary school of Widou Thiengoly, have a general health state which permits a clinical oral examination and teacher’s and/or parent’s agreement. The investigation was exhaustive and concerned the only school of the locality. More of 4/5 schoolchildren was 10.25 years ± 2.15 old. The majority (83.74%) of children presented an overjet between 0 and 3.5 mm, 1.63% presented a crossbite and 15.45% had OIM and RC different over to 2 mm. More of 30% of schoolchildren presented an overbite between 1 and 2 mm. More of 1/10 of them had an aesthetic teeth perception classified levels 8.9 and 10 corresponding to an orthodontic treatment needed according to IOTN while 20.33% had a score of 4 and 3.25% recorded score of 5 corresponding to a high treatment needed according to IOTN. The results of this study reveal that people need to be informed better about the therapeutic possibilities that orthodontics offer.展开更多
Oral diseases belong to non-communicable diseases. They are characterized by their importance especially in disadvantaged areas. The objective of this study was to measure the extent and severity of caries among rural...Oral diseases belong to non-communicable diseases. They are characterized by their importance especially in disadvantaged areas. The objective of this study was to measure the extent and severity of caries among rural populations of Widou, an area located in central Ferlo. It was a descriptive and cross-sectional study which involved 300 individuals selected using simple random sampling. The socio-demographic characteristics collected were sex, age, educational level and occupation. The dental status was rated by the prevalence of dental caries and DMF and its components. The data were analyzed with the software Epi info 3.4.5 with 5% of threshold statistical significance. The prevalence of dental caries was 89%. The mean DMF was 5.4 ± 5.6 with a maximum of 26. The mean of component “D” was 3.8 with a maximum of 24. Variables significantly associated with dental caries were sex (p = 0.012) and occupation (p = 0.03). The extent and severity of caries in rural areas of the Ferlo evoke a relatively low support or management and require efforts in prevention, directed on oral hygiene and dietary habits.展开更多
This study is an evaluation of the water potential of the Ferlo fossil valley in the Louga area in Senegal. It consisted in determining the volume of water that could be mobilized at the level of a confluence point of...This study is an evaluation of the water potential of the Ferlo fossil valley in the Louga area in Senegal. It consisted in determining the volume of water that could be mobilized at the level of a confluence point of the waters according to the flow lines, where a dam would be placed to create a reservoir. This volume of mobilizable water was compared to the average water consumption of the area in order to evaluate its adequacy or not. To do this, a delineation, physical characterization and mapping of the Ferlo watershed was done using Google Earth, Global Mapper and Arc GIS softwares. A catchment area of 28,754 sq·km was obtained with a perimeter of 976 km, an average slope of 0.52% and a hydraulic length of 336 km. Then the decennial runoff of the watershed was calculated using the CIEH method, this flow is estimated at 1120 cm/s. On the basis of this flow, the annual volume of water that can be mobilized was estimated at 11,089,758 cm per year with a solid deposits of 93 cm per year. The conclusions reached are that there is a lack of mobilizable water resources in the area and that the entire fossil valley needs to be rewatered to provide a sustainable alternative water source.展开更多
This study evaluated the molecular characterization of different ecotypes of B. aegyptiaca populations in the four sites: Koily alpha, Labgar, Ranérou and Ballou according to the environment with the aim of devel...This study evaluated the molecular characterization of different ecotypes of B. aegyptiaca populations in the four sites: Koily alpha, Labgar, Ranérou and Ballou according to the environment with the aim of developing protection strategies. We sampled leaves of B. aegyptiaca in each individual from each site to extract and amplify a fragment of mitochondrial DNA including cytochrome b and then carefully preserved. DNA extraction, polymerase chain amplification and sequencing of MT-CYB were performed in 64 individuals. Genetic diversity and structure of B. aegyptiaca were determined using the MEGA, DNasp and Arlequin software. The results showed a high haplotype diversity and low nucleotide diversity, indicating a population expansion linked to an important gene flow. Genetic distances between populations were positively correlated with geographic distance. The importance of having highlighted this genetic differentiation of the B. aegyptiaca species between these sites is to be able to understand the degree of genetic heterogeneity of each and correlate it with adaptability because genetic diversity influences the adaptation of the species.展开更多
Temporary ponds play substantial roles in preserving biodiversity in the Sahel.This study investigated the influence of anthropic and eco-hydrological factors on the plant diversity around two grazed ponds and one ung...Temporary ponds play substantial roles in preserving biodiversity in the Sahel.This study investigated the influence of anthropic and eco-hydrological factors on the plant diversity around two grazed ponds and one ungrazed pond in Ferlo,northern Senegal.Two phytoecological transects were established per pond.On each transect,homogenous herbaceous vegetation units were identified and characterized(herbaceous cover,exposure,soil texture,soil moisture and pH,average height and slope).The herbaceous flora comprised 55 species,41 genera and 22 families across the three ponds.Species of the Poaceae,particularly Eragrostis tremula and Enteropogon prieurii,mostly colonized the grazed ponds,while the ungrazed pond favored other families’species such as Achyranthes sp.,Commelina forsskaolii,Corchorus sp.The Shannon’s diversity index(H′)of Wendu Marodi(ungrazed pond)was slightly higher(4.9 bits)than that of Belel Lougal and Belel Sow(grazed ponds)with 4.8 and 4.5 bits,respectively.The equitability indices were relatively high in the three ponds(0.85,0.83 and 0.78).Eco-ecological factors distinguished four species’groupings:a Tribulus terrestris grouping colonizing the constraining and over-grazed zones,a Digitaria horizontalis grouping,and Chloris barbata grouping found in the transition zones,and an Achyranthes aspera grouping in the wetlands,where woody plants were strongly present and the anthropic action low.This study highlighted the importance of maintaining a landscape mosaic of ungrazed or semi-protected ponds and grazed ponds to preserve the herbaceous floristic diversity in the center of Ferlo(Senegal)and the Sahel in general.展开更多
The objective of this study was to develop allometric models for estimating the biomass of Sclerocarya birrea (A.Rich) Hoscht and Boscia senegalensis (Pers.) Lam. ex Poir. The inventory of these ligneous was carried o...The objective of this study was to develop allometric models for estimating the biomass of Sclerocarya birrea (A.Rich) Hoscht and Boscia senegalensis (Pers.) Lam. ex Poir. The inventory of these ligneous was carried out at Widou Thiengoly (North of Senegal). The sample consists of 43 individuals of Boscia senegalensis and 15 individuals of Sclerocarya birrea. The selected individuals were dendrometrically characterized before being cut, compartmentalized (trunk, branches, and twigs) and weighed entirely. Simple regression tests were performed to examine the most explanatory dendrometric parameter (x) for biomass (y) according to two types of models: the linear model (y = ax + b) and the polynomial model of degrees 2 (y = ax<sup>2</sup> + bx + c). The criteria for selection and validity of the models are based firstly on the tests of normality, nullity, heterogeneity and autocorrelation of the residues. The results showed that the most explanatory dendrometric parameter of the biomass was the crown surface for Boscia senegalensis and the 1.30 m diameter for Sclerocarya birrea of all the tests performed, the second-order Polynomial model is the best predictor of above ground biomass for these two species. Thus, the allometric models established to predict the biomass of these two species are: y = 0.0023x<sup>2</sup> + 0.4851x - 0.0519 for Boscia senegalensis and y = 0.35x<sup>2</sup> + 10.35x - 12.90 for S. birrea;with very significant correlation coefficients (R<sup>2</sup>) of 0.85 and 0.94 respectively. These results can be used for a sequestered carbon assessment study and will play a role in monitoring the carbon market in Africa.展开更多
In a context of climate change characterized by rising temperatures, increased greenhouse gases and frequent droughts, the Sahel is presented as one of the most vulnerable areas to the adverse effects of climate chang...In a context of climate change characterized by rising temperatures, increased greenhouse gases and frequent droughts, the Sahel is presented as one of the most vulnerable areas to the adverse effects of climate change. The Sahel is presented as one of the most vulnerable areas to the adverse effects of climate change. The objective of this study is to assess the above-ground biomass and carbon stock of three Sahelian species: Acacia raddiana tortilis (Forsk.) hayne ssp. raddiana (savi) Brenan, Acacia senegal (L.) Willd and Balanites aegyptiaca (L.). The study was carried out in northern Senegal commonly known as Ferlo. Biomasses of the populations of the three target species were first assessed by harvesting the entire epigenetic part of the species and then modelled by correlation using dendrometric parameters measured on each individual of the sample. Two models, mono-specific and multi-species, were used. The results obtained showed that the diameter at breast height (x) and the parameter best correlated to the epigeal biomass (y). The dry biomass of woody plants was 31.4 ± 15.2 kg/tree for B. aegyptiaca, 30.6 ± 13.2 kg/tree for A. senegal and 26.2 ± 11.1 kg/tree for A. raddiana;i.e. carbon equivalents of 14.75 - 14.38 - 12.31 kg/tree respectively. The amount of carbon contained in the above-ground woody biomass is estimated at 4.48 t/ha. The carbon equivalent, atmospheric CO<sub>2</sub> is estimated at 16.44 tons of CO<sub>2</sub>/ha and based on the actual density of Ferlo (108.08 ± 49.79 ind/ha) the sequestered carbon of the area is estimated at 1777.008 tons of CO<sub>2</sub>. The comparison between the models developed in this study and the multispecific or mono-specific models from the literature showed substantial differences. This study contributes to a better understanding of the contribution of Sahelian woody species to carbon sequestration and the results could be used in the framework of adaptation to climate change.展开更多
文摘This study describes the floristic composition and structure of a woody stand in the Senegalese Sahel, paying particular attention to the edaphic factors of its floristic composition. A stratified inventory considering the different relief units was adopted. Woody vegetation was surveyed using a dendrometric approach. The results obtained show that the flora is dominated by a few species adapted to drought, such as Balanites aegyptiaca (L.) Del., Calotropis procera Ait. and Boscia senegalensis (Pers.). The distribution of this flora and the structure of the ligneous plants are linked to the topography. In the lowlands, the flora is more diversified and the ligneous plants reach their optimum level of development compared with the higher relief areas. In the lowlands, there are a few woody species which, in the past, were indicative of better climatic conditions. These are Anogeissus leiocarpus (DC.), Commiphora africana (A. Rich.), Feretia apodanthera Del., Loeseneriella africana (A. Smith), Mitragyna inermis (Willd.) and Sclerocarya birrea (A. Rich). It is important that their reintroduction into reforestation projects takes account of their edaphic preference.
文摘The combined effects of climate change and human pressure have led to the progressive degradation of natural resources in semi-arid regions. Woody taxa in these regions play an important role in the functioning and services provided by semi-arid savannah by serving as forage for both domestic and non-domestic grazers. Maintaining the functioning of semi-arid savannas thus requires understanding the dynamics of these communities of woody taxa and their responses to exogenous forces, such as climate. To better understand the dynamics of woody taxa in semi-arid environments we collected dendrometric characteristics from five field sites along an environmental gradient in the Ferlo region of central Senegal. Density and basal area were found to be greater in the northern part of the zone, contrasted with the distance between individuals and crown cover, which is greater in the southern part of the zone. Stand structure estimated from the distribution according to height and diameter at breast height shows a preponderance of individuals in the shrub layer, although with a significant representation of the tree layer in southern Ferlo. Stand regeneration was better in the south and less effective in the north. There was a trend towards the rejuvenation of populations belonging to the dominant species. There were only three species for which degradation was not apparent (Balanites aegyptiaca, Acacia raddiana and Dalbergia melanoxylon), all of which have important ethnobotanical uses, suggesting that human use of taxa can play an important role in preventing degradation. Three distinct groups of woody taxa were found to correspond to gradients of precipitation, topography, and human land use pressure. Our results suggest an important role in the management and reintroduction of woody species in the Sahel and the regulation of pastoral techniques necessary for the rehabilitation of the agro-pastoral zone of Senegal.
文摘The objective of this study is to analyze the dendrochronological potential of two Sahelian species (<i><span style="font-family:Verdana;">B. senegalensis</span></i><span style="font-family:Verdana;"> and </span><i><span style="font-family:Verdana;">S. birrea</span></i><span style="font-family:Verdana;">) and to evaluate the rela</span><span style="font-family:Verdana;">tionships between their growth rings and the climate. The study was con</span><span style="font-family:Verdana;">ducted in 2016 in the Ferlo area of Senegal. The biological material consists of wood slices, taken from the trunks of these adult woody species at 0.30 m and 1.30 m from the ground after they have been felled. The technique used to examine the slices consists in identifying their rings, establishing their structures, inter-dating them and studying the relationship between the identified rings and climatic factors. The results showed that the species had thin, clear, highly visible and sharp rings. The limit of growth is marked by a line of parenchyma. Intradatation series carried out on the chronologies made it possible to estimate the ages of the individuals, which vary from 10 to 38 years for </span><i><span style="font-family:Verdana;">B. senegalensis</span></i><span style="font-family:Verdana;"> and from 29 to 50 years for </span><i><span style="font-family:Verdana;">S. birrea</span></i><span style="font-family:Verdana;">. Their average growth </span><span style="font-family:Verdana;">rates are estimated at 0.906 mm/year and 0.89 mm/year respectively. The </span><span style="font-family:Verdana;">chronological sequences are 29 years (1987-2016) for </span><i><span style="font-family:Verdana;">B. senegalensis</span></i><span style="font-family:Verdana;"> and 38 years (1964-2012) for </span><i><span style="font-family:Verdana;">S. birrea</span></i><span style="font-family:Verdana;">. The results revealed that there is no significant correlation between the growth chronologies of </span><i><span style="font-family:Verdana;">B. senegalensis</span></i><span style="font-family:Verdana;"> and the </span><span style="font-family:Verdana;">climatic regressors (temperature and precipitation). In contrast, the ring-</span><span style="font-family:Verdana;">climate relationship shows that in </span><i><span style="font-family:Verdana;">S. birrea</span></i><span style="font-family:Verdana;"> winter precipitation positively influences ring growth while temperature has no effect on ring growth in this species. This study provides a better understanding of the response of forest ecosystems to possible climate change, particularly in the current context of sustainable forest management.</span>
文摘The aim of this study was to evaluate orthodontic treatment needs among Ferlo scholars. The design of the study was descriptive and transversal. For Inclusion criteria, children must live in Widou or live around Widou’s school at least 6 km, be students at primary school of Widou Thiengoly, have a general health state which permits a clinical oral examination and teacher’s and/or parent’s agreement. The investigation was exhaustive and concerned the only school of the locality. More of 4/5 schoolchildren was 10.25 years ± 2.15 old. The majority (83.74%) of children presented an overjet between 0 and 3.5 mm, 1.63% presented a crossbite and 15.45% had OIM and RC different over to 2 mm. More of 30% of schoolchildren presented an overbite between 1 and 2 mm. More of 1/10 of them had an aesthetic teeth perception classified levels 8.9 and 10 corresponding to an orthodontic treatment needed according to IOTN while 20.33% had a score of 4 and 3.25% recorded score of 5 corresponding to a high treatment needed according to IOTN. The results of this study reveal that people need to be informed better about the therapeutic possibilities that orthodontics offer.
文摘Oral diseases belong to non-communicable diseases. They are characterized by their importance especially in disadvantaged areas. The objective of this study was to measure the extent and severity of caries among rural populations of Widou, an area located in central Ferlo. It was a descriptive and cross-sectional study which involved 300 individuals selected using simple random sampling. The socio-demographic characteristics collected were sex, age, educational level and occupation. The dental status was rated by the prevalence of dental caries and DMF and its components. The data were analyzed with the software Epi info 3.4.5 with 5% of threshold statistical significance. The prevalence of dental caries was 89%. The mean DMF was 5.4 ± 5.6 with a maximum of 26. The mean of component “D” was 3.8 with a maximum of 24. Variables significantly associated with dental caries were sex (p = 0.012) and occupation (p = 0.03). The extent and severity of caries in rural areas of the Ferlo evoke a relatively low support or management and require efforts in prevention, directed on oral hygiene and dietary habits.
文摘This study is an evaluation of the water potential of the Ferlo fossil valley in the Louga area in Senegal. It consisted in determining the volume of water that could be mobilized at the level of a confluence point of the waters according to the flow lines, where a dam would be placed to create a reservoir. This volume of mobilizable water was compared to the average water consumption of the area in order to evaluate its adequacy or not. To do this, a delineation, physical characterization and mapping of the Ferlo watershed was done using Google Earth, Global Mapper and Arc GIS softwares. A catchment area of 28,754 sq·km was obtained with a perimeter of 976 km, an average slope of 0.52% and a hydraulic length of 336 km. Then the decennial runoff of the watershed was calculated using the CIEH method, this flow is estimated at 1120 cm/s. On the basis of this flow, the annual volume of water that can be mobilized was estimated at 11,089,758 cm per year with a solid deposits of 93 cm per year. The conclusions reached are that there is a lack of mobilizable water resources in the area and that the entire fossil valley needs to be rewatered to provide a sustainable alternative water source.
文摘This study evaluated the molecular characterization of different ecotypes of B. aegyptiaca populations in the four sites: Koily alpha, Labgar, Ranérou and Ballou according to the environment with the aim of developing protection strategies. We sampled leaves of B. aegyptiaca in each individual from each site to extract and amplify a fragment of mitochondrial DNA including cytochrome b and then carefully preserved. DNA extraction, polymerase chain amplification and sequencing of MT-CYB were performed in 64 individuals. Genetic diversity and structure of B. aegyptiaca were determined using the MEGA, DNasp and Arlequin software. The results showed a high haplotype diversity and low nucleotide diversity, indicating a population expansion linked to an important gene flow. Genetic distances between populations were positively correlated with geographic distance. The importance of having highlighted this genetic differentiation of the B. aegyptiaca species between these sites is to be able to understand the degree of genetic heterogeneity of each and correlate it with adaptability because genetic diversity influences the adaptation of the species.
基金This research was funded by the Total Foundation,UMI3189‘Environnement,Sante,Societes’(UCAD,CNRS,CNRST,USTTB,UGB)the Labex DRIIHM,programme‘Investissements d’avenir’with the reference ANR-11-LABX-0010.
文摘Temporary ponds play substantial roles in preserving biodiversity in the Sahel.This study investigated the influence of anthropic and eco-hydrological factors on the plant diversity around two grazed ponds and one ungrazed pond in Ferlo,northern Senegal.Two phytoecological transects were established per pond.On each transect,homogenous herbaceous vegetation units were identified and characterized(herbaceous cover,exposure,soil texture,soil moisture and pH,average height and slope).The herbaceous flora comprised 55 species,41 genera and 22 families across the three ponds.Species of the Poaceae,particularly Eragrostis tremula and Enteropogon prieurii,mostly colonized the grazed ponds,while the ungrazed pond favored other families’species such as Achyranthes sp.,Commelina forsskaolii,Corchorus sp.The Shannon’s diversity index(H′)of Wendu Marodi(ungrazed pond)was slightly higher(4.9 bits)than that of Belel Lougal and Belel Sow(grazed ponds)with 4.8 and 4.5 bits,respectively.The equitability indices were relatively high in the three ponds(0.85,0.83 and 0.78).Eco-ecological factors distinguished four species’groupings:a Tribulus terrestris grouping colonizing the constraining and over-grazed zones,a Digitaria horizontalis grouping,and Chloris barbata grouping found in the transition zones,and an Achyranthes aspera grouping in the wetlands,where woody plants were strongly present and the anthropic action low.This study highlighted the importance of maintaining a landscape mosaic of ungrazed or semi-protected ponds and grazed ponds to preserve the herbaceous floristic diversity in the center of Ferlo(Senegal)and the Sahel in general.
文摘The objective of this study was to develop allometric models for estimating the biomass of Sclerocarya birrea (A.Rich) Hoscht and Boscia senegalensis (Pers.) Lam. ex Poir. The inventory of these ligneous was carried out at Widou Thiengoly (North of Senegal). The sample consists of 43 individuals of Boscia senegalensis and 15 individuals of Sclerocarya birrea. The selected individuals were dendrometrically characterized before being cut, compartmentalized (trunk, branches, and twigs) and weighed entirely. Simple regression tests were performed to examine the most explanatory dendrometric parameter (x) for biomass (y) according to two types of models: the linear model (y = ax + b) and the polynomial model of degrees 2 (y = ax<sup>2</sup> + bx + c). The criteria for selection and validity of the models are based firstly on the tests of normality, nullity, heterogeneity and autocorrelation of the residues. The results showed that the most explanatory dendrometric parameter of the biomass was the crown surface for Boscia senegalensis and the 1.30 m diameter for Sclerocarya birrea of all the tests performed, the second-order Polynomial model is the best predictor of above ground biomass for these two species. Thus, the allometric models established to predict the biomass of these two species are: y = 0.0023x<sup>2</sup> + 0.4851x - 0.0519 for Boscia senegalensis and y = 0.35x<sup>2</sup> + 10.35x - 12.90 for S. birrea;with very significant correlation coefficients (R<sup>2</sup>) of 0.85 and 0.94 respectively. These results can be used for a sequestered carbon assessment study and will play a role in monitoring the carbon market in Africa.
文摘In a context of climate change characterized by rising temperatures, increased greenhouse gases and frequent droughts, the Sahel is presented as one of the most vulnerable areas to the adverse effects of climate change. The Sahel is presented as one of the most vulnerable areas to the adverse effects of climate change. The objective of this study is to assess the above-ground biomass and carbon stock of three Sahelian species: Acacia raddiana tortilis (Forsk.) hayne ssp. raddiana (savi) Brenan, Acacia senegal (L.) Willd and Balanites aegyptiaca (L.). The study was carried out in northern Senegal commonly known as Ferlo. Biomasses of the populations of the three target species were first assessed by harvesting the entire epigenetic part of the species and then modelled by correlation using dendrometric parameters measured on each individual of the sample. Two models, mono-specific and multi-species, were used. The results obtained showed that the diameter at breast height (x) and the parameter best correlated to the epigeal biomass (y). The dry biomass of woody plants was 31.4 ± 15.2 kg/tree for B. aegyptiaca, 30.6 ± 13.2 kg/tree for A. senegal and 26.2 ± 11.1 kg/tree for A. raddiana;i.e. carbon equivalents of 14.75 - 14.38 - 12.31 kg/tree respectively. The amount of carbon contained in the above-ground woody biomass is estimated at 4.48 t/ha. The carbon equivalent, atmospheric CO<sub>2</sub> is estimated at 16.44 tons of CO<sub>2</sub>/ha and based on the actual density of Ferlo (108.08 ± 49.79 ind/ha) the sequestered carbon of the area is estimated at 1777.008 tons of CO<sub>2</sub>. The comparison between the models developed in this study and the multispecific or mono-specific models from the literature showed substantial differences. This study contributes to a better understanding of the contribution of Sahelian woody species to carbon sequestration and the results could be used in the framework of adaptation to climate change.
