Sahel Savannah Research Articles

Land transformation across agroecological zones reveals expanding cropland and settlement at the expense of tree-cover and wetland areas in Nigeria

ABSTRACT Evaluating how land cover is being transformed is essential to identify patterns necessary to infer the change trajectories and the driving factors. This study considers the case of Nigeria, where various natural ecosystems are being converted and for which a current national scale assessment at high spatial resolution is lacking. Producing 30 m Landsat-based time-series data, we analyze change among land cover types (i.e. tree-covered area, grassland, wetland, waterbody, cropland, artificial surface, and otherland) across seven agroecological zones. The annual change intensity was assessed at multi-levels across two time-intervals (i.e. 2000–2013, 2013–2022). Distinguishing between natural land cover and human activity-related land-use, we estimate the extent of change signifying how humans have appropriated natural land cover. Insights from analysis at the interval level reveal that land transformation accelerated from 3.3% in 2000–2013 to 4.5% during 2013–2022 in all agroecological zones (e.g. rainforest, mangrove), except in Sudan savannah and Sahel savannah where speed was higher in 2000–2013 as grasslands were increasingly cultivated. Cropland expanded almost two-fold (22% to 37%), whereas tree-cover declined from 50% to 31% and wetland from 7% to 3.7% over the 23 years. Much loss of natural land cover (e.g. tree-cover, grassland, and wetland) to cropland occurred in 2000–2013 (22%) when most irrigation schemes in Nigeria were established. In contrast, the loss of natural land cover to settlement (0.9%) during 2000–2013 increased to 2.0% in 2013–2022. Of all agroecological zones, the mangrove zone was most disturbed as its persisting land cover areas reduced from 69% to 5% between 2000–2013 and 2013–2022. The amount of persisting land cover was highest in the Sudan savannah at 44% in 2000–2013 and 49% in 2013–2022. Processes of human-appropriated natural land cover in Nigeria are related to urbanization and cropland expansion into natural areas with some instances of natural regeneration, especially in croplands and abandoned settlement areas.

Modelling Dynamic Linkage between Climate Change and Food Inflation in Nigeria

The study delves into the critical issue of climate change and its detrimental impact on various regions worldwide, including Nigeria. It emphasizes the urgent need for global efforts to mitigate these effects and advocates for measures to address human activities contributing to climate dynamics. Specifically, the study empirically examines the affiliation between climate change shocks and food price inflation in Nigeria using a Nonlinear Autoregressive Distributed Lag (NARDL) approach. The dataset covers the period from January 2011 to December 2022.The empirical findings reveal a robust cointegrating relationship between climate change shocks and food price inflation in Nigeria. Notably, climate change shocks significantly contributed to rising food prices within the study period. Furthermore, the Error Correction Term (ECT), estimated at 52 percent, indicates that food price inflation adjusts by 52 percent in the current month to counteract the initial shock experienced in the previous month. The Dynamic Multiplier graph, along with a 95 percent confidence interval, demonstrates that the explanatory variables exert substantial influence on food price inflation in Nigeria during the study period. Considering these findings, the study recommends that Nigeria should transit from traditional agricultural practices to Climate-Smart Agriculture to address future needs and climate-related challenges. Additionally, the government and stakeholders should implement alternative practices such as irrigation and the replenishment of shrinking water bodies in the Sudan and Sahel savannah regions.

Morphological variations among populations of Bulinus forskalii (Ehrenberg, 1831) from Cameroon

ABSTRACT Climatic stratification from equatorial rainforest to Sahelian savannah in Cameroon implies successive bioclimatic ecosystems, various natural and artificial situations that may generate morphological and genetic adaptation of populations of Bulinus forskalii (Ehrenberg, 1831) which is widely distributed throughout the country. The present research was undertaken on 955 snails sampled from 12 populations along a south–north transect to investigate morphological variations of shells. Shell colour varied from dark brown to whitish with Sudano–Sahelian shells being brownish through to whitish, shouldered and strongly carinate. Morphometric characters varied greatly from one population to another, with all shell parameters being highly correlated to shell height. Sudano–Sahelian shells were smaller than equatorial shells. From Sangmélima in the equatorial forest region to Marao in the Sudano–Sahelian region a gradual decrease of shell dimensions was apparent, indicating a morphocline. This could reflect the role played by ecological factors on snail population dynamics.

The resting behavior of malaria vectors in different ecological zones of Ghana and its implications for vector control

BackgroundIn sub-Saharan Africa there is widespread use of long-lasting insecticidal nets and indoor residual spraying to help control the densities of malaria vectors and decrease the incidence of malaria. This study was carried out to investigate the resting behavior, host preference and infection with Plasmodium falciparum of malaria vectors in Ghana in the context of the increasing insecticide resistance of malaria vectors in sub-Saharan Africa.MethodsIndoor and outdoor resting anopheline mosquitoes were sampled during the dry and rainy seasons in five sites in three ecological zones [Sahel savannah (Kpalsogo, Pagaza, Libga); coastal savannah (Anyakpor); and forest (Konongo)]. Polymerase chain reaction-based molecular diagnostics were used to determine speciation, genotypes for knockdown resistance mutations (L1014S and L1014F) and the G119S ace1 mutation, specific host blood meal origins and sporozoite infection in the field-collected mosquitoes.ResultsAnopheles gambiae sensu lato (s.l.) predominated (89.95%, n = 1718), followed by Anopheles rufipes (8.48%, n = 162) and Anopheles funestus s.l. (1.57%, n = 30). Sibling species of the Anopheles gambiae s.l. revealed Anopheles coluzzii accounted for 63% (95% confidence interval = 57.10–68.91) and 27% (95% confidence interval = 21.66–32.55) was Anopheles gambiae s. s.. The mean resting density of An. gambiae s.l. was higher outdoors (79.63%; 1368/1718) than indoors (20.37%; 350/1718) (Wilcoxon rank sum test, Z = − 4.815, P < 0.0001). The kdr west L1014F and the ace1 mutation frequencies were higher in indoor resting An. coluzzii and An. gambiae in the Sahel savannah sites than in the forest and coastal savannah sites. Overall, the blood meal analyses revealed that a larger proportion of the malaria vectors preferred feeding on humans (70.2%) than on animals (29.8%) in all of the sites. Sporozoites were only detected in indoor resting An. coluzzii from the Sahel savannah (5.0%) and forest (2.5%) zones.ConclusionsThis study reports high outdoor resting densities of An. gambiae and An. coluzzii with high kdr west mutation frequencies, and the presence of malaria vectors indoors despite the use of long-lasting insecticidal nets and indoor residual spraying. Continuous monitoring of changes in the resting behavior of mosquitoes and the implementation of complementary malaria control interventions that target outdoor resting Anopheles mosquitoes are necessary in Ghana.Graphical abstract

Assessment of the Ovulation Inducing Activity of Extract and Various Solvent Fractions of Caralluma dalzieliiN E Brown

IntroductionCaralluma dalzielii N E Brown (Asclepiadiaceae) is a cactus‐like shaped plant that grows mainly in the Sahel savannah region of Africa. Its decoction is traditionally used to promote fertility. The aim of the study was to determine the ovulation inducing effect of extract and various solvent fractions of Caralluma dalzielii.Materials and methodsThe DCM/methanol (1:1) extract (DME) was fractionated by chromatography in a silica gel (60‐200 mm mesh) column. The extract was eluted successively using petroleum ether, ethyl acetate and methanol in order of increasing polarity. Phytochemical studies were carried out on the extract and fractions following standard procedures. Acute toxicity study was conducted using OECD 425 guidelines at a limit dose of 2000 mg/kg. Female rats with regular 4‐day oestrus cycle were allotted into 11 groups (n=6). Treatment of the rats started at pro‐oestrus phase of oestrus cycle. The rats received 2 µg s.c. each of a GnRH‐antagonist, cetrorelix, at 1.00 p.m. which resulted in blockade of ovulation. Two hours later, rats were treated with DME, petroleum ether fraction (PEF) and methanol fraction (MF) (500 and 1000 mg/kg p.o), ethyl acetate fraction (EAF) (10, 25 and 40 mg/kg p.o.), distilled water (5 mL/kg) and hCG (75 IU/kg/s.c) as positive control. The next day after the treatment, rats were sacrificed, ovaries were excised and placed in Bouin’s solution for histological analysis. Blood samples were collected via cardiac puncture under anaesthesia for serum hormonal profile.ResultsA 3 g (10% w/w), 8.4 g (28% w/w) and 6.5 g (21.67 % w/w) of the PEF, EAF and MF respectively were realised. The extract, EAF and MF contained alkaloids, saponins, flavonoids, tannins, steroids and cardiac glycosides while PEF contained steroids and cardiac glycosides only. The LD50 of the extract and fractions were greater than 2000 mg/kg while that of EAF was calculated to be 70.71 mg/kg. LH levels decline immediately after ovulation. The extract, fractions and hCG produced significant (p&lt;0.05) reduction in the LH levels. They thus reversed cetrorelix‐induced ovulation blockade. Only the 1000 mg/kg of the extract caused a significant (p&lt;0.05) reduction in the LH levels. All the animals showed oestrus cycle phase the following day except the control animals. Amongst the extract and fractions, the PEF showed the greatest ability to reverse cetrorelix‐induced ovulation blockade by causing greater reduction of LH levels than the other groups. EAF at all dose levels also significantly (p&lt;0.05) lowered the LH levels more than the control (Table 1). MF showed a significant (p&lt;0.05) reduction of LH levels only at 1000 mg/kg. Histology of the ovaries of the treated animals showed the presence of fresh corpus lutea in their various numbers. However, this was not seen in the distilled water control and the 1000 mg/kg of MF groups (Figure 1).ConclusionThe result showed that Caralluma dalzielii extract and fractions possess ovulation inducing activity. Bioactive compounds could be isolated from both EAF and PEF which showed the highest ovulation inducing activity.

Spatial and Seasonal Estimation of Tropospheric Radio Refractivity in Nigeria

The spatial and seasonal variation of tropospheric radio refractivity of Nigeria has been studied using meteorological variables (temperature, relative humidity and pressure) retrieved from the archive of the United States’ National Aeronautics for Space Administration (NASA). This work established a seasonal variation. The results also revealed an increase in radio refractivity from minimum of about 270N-units at Abadam to maximum of about 415N-units at Warri. The variation of radio refractivity is synchronous with rainfall in most of the stations especially those in the Guinea Savannah, Tropical Rainforest and Coastal areas where the effects of august break manifest vividly on the curves. Intense refractivity was measured mostly in the tropical rainforest and coastal areas. This could be attributed to the intensity of rain and the length of the wet season in those locations. The Sahel, Sudan and Guinea savannah which experience less rain with short period of wet season recorded reduced refractivity. Just like rainfall, the movement of Inter Tropical Discontinuity (ITD) is also found to be linked to the variation of the radio refractivity. The northward movement of the ITD brings with it elevated refractivity while the southward movement leads to reduced refractivity. This is because the ITD is an element of two high pressure cells which influences its motion. Majorly, the seasonal variation is found to be the product of climate except in some high ground areas where the topography was found to be majorly responsible.

A Possible Link Between Consumption of Sorghum based Products and Prevalence of Hepatocellular Carcinoma In The Sahel Savannah Zone of Nigeria: A Risk Assessment

The study area (Sahel savannah zone of Nigeria) was delineated into five sampling districts, which were further delineated into three localities from where raw and processed sorghum based products were collected. Sorghum based products such as gruel, pap and chincoins “dambu”were sampled using a quantitative food frequency questionnaire. Anthropological measurements of volunteer subjects along with the quantity of food consumed by the respondents was recorded. The mycotoxin concentration in both raw and processed sorghum products was determined using high performance liquid chromatography (HPLC/MS). The determined mycotoxins concetrations in both the raw and processed samples were further used to determine the amount of mycotoxins consumed by respondents in different age groups. Aflatoxin induced Hepatocelluar carcinoma (HCC) in was subsequently determined in communities (within the zone) that subsist on such products. Cumulative average daily consumption of sorghum based products was found to be 192.5±8.32g/day, 617.0±16.45g/day, 810.2±23.24g/day and 746.1±21.02g/day for the infants, children, adults and elderly respectively. A significant difference (P = 0.05) exists between the mycotoxins concentration in raw and the processed sorghum-derived products in the study area. Despite the processing methods employed, the values for PTDI and TDI for mycotoxins, were found to be far above the limits sets by the regulatory bodies. The predictive incidence of HCC and the burden aflatoxin induced HCC in the HbsAg+was found to be 479.9/100000, 30.0/100000, 28.8/100000, 172.2/100000 in the infants, children, youth and the elderly respectively.

Evidence of Climate variability by the Spatio-Temporal Analysis of Temperature in the City of Sokoto

Temperature is crucial in observing changes occurring in the environment, such as climate change. Climate change is caused by the emission of excessive greenhouse gas and has been acknowledged as the main cause of various environmental impacts such as an increase in the flood scenario, frequent droughts, increasing wildfires, and heatwaves in various parts of the world. Temperature behaviour which has been studied in the city of Sokoto was used as a yardstick to check for the presence of variance in climate. Temperature data were gotten from the Nigerian Meteorological Agency (NIMET) that spanned thirty-one years (1980–2010) was used for this study. ANOVA and the Mann Kendall trend test were used to analyze the data used. The ANOVA findings revealed that the maximum and minimum temperatures differed significantly between the months. The Mann-Kendall trend test results suggest an increasing trend in maximum temperature and a declining trend in minimum temperature in the annual statistics. The monthly trend was made up of both increasing and decreasing trends. The city of Sokoto being located in the region of the Sahel savannah has very sensitive to minor changes in climate variance, hence this result will help in the planning of agriculture-related activities such as planting time, type of crops to plant, type of animals to be reared, types of animal diseases to provide vaccines for, etc.

Testing the accuracy of Soil Testing Kit® Transchem

Soil testing is key to soil fertility management as it serves as a fertilizer application guide to farmers, scientists and consultants. It gives information on soil nutrient status and its supplying capacity. Laboratory (LB) procedures have been the most reliable approach for soil nutrients analyses. However, it is costly and nonpoint. Thus, the use of in–situ testing kit emerges and becomes prominent. Notwithstanding, applicability of soil testing kit must be validated by laboratory test. This work aimed to examine the reliability/suitability of Soil Testing Kit® Transchem (SK) in determining selected soil nutrients in Sahel Savannah, Nigeria. Twentyfive replicate soil samples were collected from 12°47’86’’-12°20’96’’N and 4°38’37’’-4°188’02’’E, Kebbi State Nigeria and used to test soil pH, N, P, K and soil organic carbon (SOC) by SK and LB. The SK uses colour chart and comparator for rating nutrients status qualitatively into; low, medium and high and up to very high for P. The LB results were transformed to qualitative data by corresponding the values with soil rating standardinto low, medium and high. To perform statistics, weighting was done by assigning weight load to each category; low = 1, medium = 2 and high = 3. The two methods were compared using t-test, regression and descriptive analyses. Results showed non-significant difference between the two methods for soil contents of N, P and K. However, SK poorly estimated soil pH and SOC. Correlation and regression coefficients (r = 0.915 and R2 = 0.838, respectively) indicated reliability of the SK. It is concluded that SK can be reliably used for N, P, and K but not soil pH and SOC estimation for soils in Sahel savannah of Nigeria.

Use of plant resources by refugees from Minawao and their impact on the Sahelian savannah of Cameroon

The study took place in the refugee camp of Minawao (Far North, Cameroon) between 2018 and 2020. The aim was to know the impact of the use of plant resources by Nigerian refugees settled in Cameroon since 2013 in order to claim a sustainable management of these resources. To achieve this objective, a structured and semi-structured survey was carried out in the refugee households. During this socio-economic survey, 350 refugees were surveyed. Excel was used to calculate averages and draw histograms. It was found that the majority of the refugees in this site are young (60.45%) and they are more involved in the use of plant resources which has a negative impact on vegetation. Donations (92.33%) are the first sources of income for the refugees and wood (82.33%) is more used for cooking in the households. Acacia albida, Adansonia digitata, Anogeissus leiocarpus, Azadirachta indica, Parkia biglobosa and Tamarindus indica are shown to be important in the pharmacopoeia, in food or as wood energy. Faced with this situation, the humanitarian community present in Cameroon and throughout the world must take full measure regarding the choice of sites for the settlement of refugees and the reforestation of areas already threatened by climate change. It will be important to put in place specific sustainable management systems to accelerate this reforestation of the camp.

Population structure and diversity of Plasmodium falciparum in children with asymptomatic malaria living in different ecological zones of Ghana

BackgroundGenetic diversity in Plasmodium falciparum populations can be used to describe the resilience and spatial distribution of the parasite in the midst of intensified intervention efforts. This study used microsatellite analysis to evaluate the genetic diversity and population dynamics of P. falciparum parasites circulating in three ecological zones of Ghana.MethodsA total of 1168 afebrile children aged between 3 to 13 years were recruited from five (5) Primary schools in 3 different ecological zones (Sahel (Tamale and Kumbungu), Forest (Konongo) and Coastal (Ada and Dodowa)) of Ghana. Asymptomatic malaria parasite carriage was determined using microscopy and PCR, whilst fragment analysis of 6 microsatellite loci was used to determine the diversity and population structure of P. falciparum parasites.ResultsOut of the 1168 samples examined, 16.1 and 39.5% tested positive for P. falciparum by microscopy and nested PCR respectively. The genetic diversity of parasites in the 3 ecological zones was generally high, with an average heterozygosity (He) of 0.804, 0.787 and 0.608 the rainy (peak) season for the Sahel, Forest and Coastal zones respectively. The mean He for the dry (off-peak) season were 0.562, 0.693 and 0.610 for the Sahel, Forest and Coastal zones respectively. Parasites from the Forest zone were more closely related to those from the Sahel than from the Coastal zone, despite the Coastal zone being closer in physical distance to the Forest zone. The fixation indexes among study sites ranged from 0.049 to 0.112 during the rainy season and 0.112 to 0.348 during the dry season.ConclusionA large asymptomatic parasite reservoir was found in the school children during both rainy and dry seasons, especially those in the Forest and Sahel savannah zones where parasites were also found to be related compared to those from the Coastal zone. Further studies are recommended to understand why despite the roll out of several malaria interventions in Ghana, high transmission still persist.

Larval habitat diversity and Anopheles mosquito species distribution in different ecological zones in Ghana

BackgroundUnderstanding the ecology of larval malaria and lymphatic filariasis mosquitoes in a changing environment is important in developing effective control tools or programmes. This study characterized the breeding habitats of Anopheles mosquitoes in rural communities in different ecological zones in Ghana during the dry and rainy seasons.MethodsThe spatio-temporal distribution, species composition, and abundance of larval Anopheles mosquitoes in breeding habitats were studied in five locations in three ecological zones of Ghana. These were Anyakpor (coastal savannah area), Duase (forest area), and Libga, Pagaza, and Kpalsogu (Sahel savannah area). Larvae were collected using standard dippers and were raised in the insectary for identification.ResultsOut of a total of 7984 mosquito larvae collected, 2152 (27.26%) were anophelines and were more abundant in the rainy season (70.82%) than in the dry season (29.18%). The anophelines comprised 2128 (98.88%) An. gambiae s.l., 16 (0.74%) An. rufipes, and 8 (0.37%) An. pharoensis. In the coastal savannah and forest zones, dug-out wells were the most productive habitat during the dry (1.59 larvae/dip and 1.47 larvae/dip) and rainy seasons (11.28 larvae/dip and 2.05 larvae/dip). Swamps and furrows were the most productive habitats in the Sahel savannah zone during the dry (0.25 larvae/dip) and rainy (2.14 larvae/dip) seasons, respectively. Anopheles coluzzii was the most abundant sibling species in all the ecological zones. Anopheles melas and An. arabiensis were encountered only in the coastal savannah and the Sahel savannah areas, respectively. Larval habitat types influenced the presence of larvae as well as larval density (p < 0.001). The land-use type affected the presence of Anopheles larvae (p = 0.001), while vegetation cover influenced larval density (p < 0.05).ConclusionThe most productive habitats were dug-out wells in the coastal savannah and forest zones, and furrows from irrigated canals in the Sahel savannah zone. Anopheles coluzzii was the predominant vector species in all the ecological zones. The abundance of Anopheles breeding habitats and larvae were influenced by anthropogenic activities. Encouraging people whose activities create the larval habitats to become involved in larval source management such as habitat manipulation to stop mosquito breeding will be important for malaria and lymphatic filariasis control.

High photosynthetic capacity of Sahelian C3 and C4 plants.

The semi-arid ecosystems of the African Sahel play an important role in the global carbon cycle and are among the most sensitive ecosystems to future environmental pressures. Still, basic data of photosynthetic characteristics of Sahelian vegetation are very limited, preventing us to properly understand these ecosystems and to project their response to future global changes. Here, we aim to study and quantify key leaf traits, including photosynthetic parameters and leaf nutrients (Nleaf and Pleaf), of common C3 and C4 Sahelian plants (trees, lianas, and grasses) at the Dahra field site (Senegal). Dahra is a reference site for grazed semi-arid Sahelian savannah ecosystems in carbon cycle studies. Within the studied species, we found that photosynthetic parameters varied considerably between functional types. We also found significant relationships between and within photosynthetic parameters and leaf traits which mostly differed in their slopes from C3 to C4 plants. In agreement with the leaf economic spectrum, strong relationships (R2 = 0.71) were found between SLA and Nleaf whereby C3 and C4 plants showed very similar relationships. By comparing our data to a global dataset of plant traits, we show that measuredSahelian plants exhibit higher photosynthetic capacity (Asat) compared to the non-Sahelian vegetation, with values that are on average a fourfold of the global average. Moreover, Sahelian C3 plants showed photosynthetic nutrient use efficiencies that were on average roughly twice as high as global averages. We interpreted these results as the potential adaptation of Sahelian plants to short growing season lengths via an efficient nutrient allocation to optimize photosynthesis during this period. Our study provides robust estimates of key functional traits, but also traits relationships that will help to calibrate and validate vegetation models over this data-poor region.

Appraisal of Groundwater Potential of Fadama Areas within Northern Nigeria: A Review

Nigeria is a country endowed with alluvial aquifers that occur along major river valleys, in low lying areas which are frequent to flooding during the rainy season. They are scattered across the ecological zones of Guinea savannah, Sudan savannah and the Sahel Savannah and are the thickest along the river Niger and river Benue. The irrigated flood plains (Fadama) are formed by the deposition of transported weathered exogenic terrigenous materials derived from the surrounding basement rocks. These shallow aquifers are mostly unconfined and are recharged through flash flooding events which make them hold great groundwater resources for dry season farming. The fertility of the soils with their residual moisture content makes them attractive for dry season farming. The potential and importance of Fadama agriculture for food production and economic development are crucial, given the recent rising food prices, climatic changes, environmental risks associated with “modern” agriculture, modelled farming systems and population growth. Fadama areas are therefore of critical importance to the survival and economic development of millions of rural dwellers. This paper reviews the groundwater potential of the Floodplains of Fadama for dry farming systems in semi-arid northern Nigeria.

Quantification of Biomass and Carbon Storage of the Herbaceous Stratum Around Refugee Camps: Case Study of Minawao Site in Cameroon

Degradation of the savannah region contributes indirectly to climatic changes. In order to come across the impacts of anthropogenic actions on the herbaceous stratum, a carbon stock estimation study was conducted in the Sahelian savannah of Cameroon. Herbaceous inventories were carried out in each plant formation and also in each transect demarcated from refugee sites. These inventories were carried out in a 10 m x 10 m plot. 5 circles with a radius of one (01) meter were delimited with a (01) ribbon in this quadrat. After data analysis in a laboratory, the wooded savannah (2.44±3.70 t/ha) shows the greatest amount of herbaceous biomass followed by the forest gallery (1.81±2.47 t/ha). The presence of a large quantity of carbon influence the locality of Zamay (0.54±0.10 tC/ha), meanwhile the village of Minawao present a very small quantity (0.23±0.11 tC/ha), where the refugees are settled. The impacts of the refugees are greater on carbon sequestration than those of the local populations. This study contributes to the understanding of carbon sequestration on the savannah region. To strengthen the potential of the herbaceous plants in this ecosystem are needed to minimize its degradation so that it can be a sustainable source of carbon stored by herbaceous.

Effects of climatic variability on cassava production in Nigeria

Climate change has brought about irregularity in pattern and intensity of climatic variables such as rainfall and temperature that are important in crop production; making planning in agriculture difficult. The importance of cassava in the diet of Nigerian and its industrial use necessitate the need to examine the effects of climatic variability on cassava production. Secondary data obtained from Nigerian Meteorological Agency (NIMET) were used for the study. Analysis of Variance and Error Correction model were utilized. The study showed that the rainforest zone had the highest averages of annual rainfall (1709mm) and relative humidity (82.1%) while the Sahel savannah had the highest mean annual temperature (35.3oC). The variability in annual rainfall and relative humidity was low in the rainforest zone. The study showed that the rainforest zone had the least dispersion of average annual relative humidity (2.06%) while the guinea savannah had highest dispersion (4.68%). The average cassava output from the agro-ecological zones was 49,118,871MT per year. Rainforest and guinea savannah accounted for 56.3% and 41.9% of total cassava output respectively. There were significant variations in the climatic variables (rainfall and temperature) among the agro-ecological zones but not significant among the years (p&gt;0.05). The annual rainfall and solar radiation were the factors that influenced cassava output in all the agro-ecological zones. The need for affordable irrigation by cassava farmers and the adoption of Climate-Smart Agriculture are recommended to boost cassava production in Sudan savannah and Sahel savannah.

Investigation of Trends in Agricultural and Meteorological Drought in Nigeria

Investigating the trend in meteorological and agricultural drought is important in water resources management. Drought affects agriculture, water resources and the ecosystems of Nigeria. This study investigated the trend in meteorological and agricultural drought in the guinea savannah, sudan savannah and sahel savannah agro ecological zones in Nigeria by using SPI (standardized precipitation index), SPEI (standardized precipitation and evapotranspiration index) and SSI (standardized soil moisture index) indices. SPI considers only precipitation, SPEI considers both precipitation and potential evapotranspiration to determine drought and SSI considers soil moisture to evaluate soil moisture deficit for both short and long period. Precipitation data (1981-2015) was obtained from Nigerian Meteorogical Agency (NIMET) and soil moisture data (1981-2015) for 3 weather stations (1 from each zones) was obtained from the Climate Prediction Center (CPC). The result showed that; (1) Trend analysis revealed that the hypothesis of no trend was rejected in the three agro-ecological zones studied; (2) There was an observed significant drying trend at 95% significant level; (3) Over the three zones, the drought indicators showed significant trend; and (4) Comparison analysis of the 3 drought indices used in this study shows that SPI and SPEI are more consistent in the three zones showing relative correlation compared to SSI.

Sensitivity of FAO Penman–Monteith reference evapotranspiration (ETo) to climatic variables under different climate types in Nigeria

AbstractUnderstanding the impact of changes in climatic variables on reference evapotranspiration (ETo) is important for predicting possible implications of climate change on the overall hydrology of an area. This study aimed to determine the effects of changes in ETo with respect to changes in climatic variables. In addition, the specific objective was to determine the sensitivity coefficients of ETo in seven different locations in Nigeria with distinct agroecology, namely Maiduguri (Sahel savannah), Sokoto (Sudan savannah), Kaduna (Guinea savannah), Jos (Montane), Enugu (Derived Savannah), Ibadan (tropical rainforest), and Port Harcourt (coastal). The results showed that ETo is most sensitive to changes in maximum temperature (Tmax) in Maiduguri, Sokoto, Kaduna, and Jos. In Enugu and Ibadan, ETo is most sensitive to changes in solar radiation (Rs), while in Port Harcourt, ETo is most sensitive to relative humidity (RH). Overall, based on the average annual sensitivity coefficients (SCs) of the study area, the SC is ranked in the order: RH &amp;gt; Rs &amp;gt; Tmax &amp;gt; U2 &amp;gt; Tmin. Also, the results showed positive SCs of ETo to Rs, Tmax, U2, Tmin, and negative SC for RH. This study can serve as a baseline for sustainable water management in the context of climate change and adapted to areas with a similar climate.

Climate change, Sahel Savanna, gum arabic and biotechnology

The Sahel Savannah has witnessed increased aridity and expansion to the Sudan Savannah. This has affected livelihood including loss of water bodies. The natural tendency is to migrate or develop survival strategy. In both cases, there are severe environmental and social consequences. The gum arabic tree is well adapted to arid climate and the Sahel Savannah in particular. Biotechnology facilitates production of planting materials and genetic improvement, as gum arabic is amenable to application of biotechnology. This will facilitate response of gum arabic agroforestry to several aspects of the Sustainable Development Goals of the United Nations. The objective of this paper was to highlight the application of biotechnology to enhance the potential of gum arabic to address the degradation of the Sahel savannah.

THE ESTIMATION OF MICROALGAE CULTIVATION PRODUCTIVITY FOR BIOFUEL PRODUCTION IN NIGERIAN CONDITIONS

Microalgae constitute the main source of materials that can be used as raw materials for many high value bioproducts, the most prominent ones of which are vitamins, lipids, chlorophyll and carotenoids.The key to economic production of biomass and bioproducts from microalgae is to optimize their growth conditions. Microalgae require optimal lighting conditions for efficient photosynthesis. This article focuses on the conditions for growing microalgae mostly chlorella sp. Microalgae require optimal lighting conditions for efficient photosynthesis. Photoperiod, light intensity and wavelength of light are some of the important factors affecting the rate of photosynthesis. Light conditions directly affect the growth, pigment content and protein amount in microalgae. The aim of this paper is to model the productivity of biomass and the accumulation of lipids in algae, as well as to calculate the productivity when cultivated under weather conditions in different regions of Nigeria.The intensity of solar radiation per day is usually one of the variables collected by meteorological stations in Nigeria. Satellite derived solar irradiance over 25 locations in the 5 climatic zones of Nigeria (tropical rainforest, Guinea savannah , Sahel savannah , Sudan savannah , and Mangrove swamp forest ) was analyzed. This article analysis the prospect of production of biofuel of the third generation using microalgal biomass in the weather conditions typical regions of Nigeria. Taking into account the average monthly density of solar radiation in the main regions of Nigeria kWh/m2 .day to estimate the possibiity of achieving crop yields of microalgal biomass per square meter of cultivated areas in the weather conditions of Nigeria. In addition, advantages and current limitations of biodiesel production, quantitative and qualitative feasibility of microalgal biodiesel, and its economic feasibility are discussed.