Vegetation and its relation to soil nutrient and salinity in the Calabar mangrove swamp, Nigeria

The study examines vegetation – environment relationships. Vegetation measurements included species frequency, density, diameter and tree height, while environmental measurements were soil particle size distribution, acid properties (pH, Al, SO4), nutrient cations (Ca, Na, Mg, K), organic carbon, nitrogen, phosphorus and chloride content. Nypa fruticans was the dominant species in the A stratum (> 3 m tall) while Rhizophora mangle was dominant in the B stratum (1–3 m tall). The C stratum (< 1 m tall) was dominated by mangrove, Nypa and Raphia saplings. Silt was dominant and the most variable particle size fraction. A principal components analysis of the soil data indicated the first three dominant components influencing the vegetation were salinity, nutrient and soil texture. Tree height and density correlated highly with the salinity and soil texture gradients (P < 0.01), while basal area correlated with salinity and nutrient gradients (P < 0.01). While Avicannia africana in the A stratum was influenced largely by the salinity and soil texture gradients. Nypa fruticans in the B stratum was influenced by salinity and nutrients

Gradient analysis in mangrove swamp forests

Gradient analysis is used as a research method to investigate species occurrence relative to the complex environmental gradient characteristic of mangrove swamps. Physiographic mangrove habitats are sampled using quadrats located along transects established from the water channels inland. Ordination of species importance values along composite habitat transects reveals species modal gradations rather than marked zonation of the species as implied in Clementsian succession theories. Ordination of Pearson ’s correlation coefficients between composite quadrats of the habitat transect indicates mostly peaks and dips in the gradients, implying that the vegetation and environment are in a state of dynamic equilibrium with each other. There are constant species-environment adjustments and interactions along the gradient and hence an absence of stable conditions in the swamps. Mangroves are perpetuated along shorelines as long as their environmental tolerance limits are not exceeded and their growth is optimal relative to the habitat conditions in which they occu

Soil-vegetation interrelationships of mangrove swamps as revealed by multivariate analyses

Vegetation and soil of mangrove swamps were studied with the aim of understanding the interrelationships of the mangrove ecosystem. Principal components analysis (PCA) was used to generate a hypothesis that the distribution patterns of mangrove vegetation were influenced by variation in soil properties. The hypothesis, tested by simple correlations of vegetation components and soil variables, revealed a primary nutrient/salinity factor as explaining species variation on the first principal component, while the second was explained by physical site quality and micronutrients. Canonical correlation analysis (COR) was also used to relate both subsystems directly. The primary relationship between vegetation and soil was confirmed to be in terms of nutrient and salinity variation. Several species, e.g. Avicennia africana and Rhizophora spp., indicated little or no relation to soil calcium and magnesium levels. A spatial segregation of species was also apparent due to selective tolerance and adaptation of the species to levels of salt concentrations. Field moisture, associated with tidal flooding, was observed to affect both subsystems through their effect on nutrient supply, chloride concentrations and organic carbon

Mangrove swamp at a saline/fresh water interface near Creek Town, Southeastern Nigeria

The Creek Town mangrove swamp occurs at the saline/fresh water interface within the ever-wet humid tropical zone of Southeastern Nigeria. A survey of the swamp was undertaken to map the mangrove physiographic habitats, and to obtain vegetation and environmental measurements. Due to the dynamic nature of the swamp landscape, several physiographic mangrove habitats have evolved. Habitat differences relate to swamp gradient, salinity variation, substrate texture <and carbonate content of the soil. Species presence and abundance vary between the habitats. Diurnally flooded tidal creek and distributary wetlands are dominated by Acrostichum aureum and Nypa fruticans in association with Rhizophora spp. and Avicennia afiicana. Raphia spp. and Vossia cuspidata which are upland forest species have invaded the supratidal and hinterland levee habitats due to increasing salinity tolerance and competitive abilities. Vegetation zonation is apparent from the channels inland but there are quirks in the zonation pattern due to variations in local topography within the species zones. The environmental conditions and species distribution are similar to other transitional mangroves of the West Africa-Americas Mangrove Formation

Ecological classification of Nigerian mangroves using soil nutrient gradient analysis

Direct gradient analysis was used to relate the structure of mangrove communities to soil nutrient gradients. The predominant cations in the alluvial soils were magnesium and calcium, the values ranging from 8.6 ± 0.9 to 24.6 ± 2.0 me per 100 g. Organic carbon was high in the soils, ranging from 3.5% to 10.4%. All soil nutrients varied seasonally, in response to wet and dry periods of the climate. Correlation of species with soil nutrients indicated the nutrient status of the soils to be best defined in terms of calcium for the A stratum (species> 3 m tall), calcium/postassium for the B stratum (species 1–3 m tall) and magnesium for the C stratum (species < 1 m tall). Ecological group classification shows that Avicennia africana and Nypa fruticans occurred almost exclusively at the highest calcium values of 20.8 and 17.6 me per 100g, respectively. Acrostichum aureum and Sesuvium portulacastrum are insensitive to the magnesium gradient. The analysis revealed an overlapping range of occurrences for most of the species although with varying ecological optima along the gradient

An ordination study of mangrove swamp communities in West Africa

Mangrove vegetation and soil were analysed with a view to understanding the community structure and soil relationship in mangrove ecosystems. Coverage values of all plants, frequency, density and basal area for trees were obtained. Soil properties measured included pH, field moisture, bulk density, organic carbon, Al3+, SO4 2- and Cl-. Principal components ordination of the vegetation data established six mixed mangrove community types. All soil properties varied significantly between the community types, but was most marked in the cases of CO3 2- and SO4 2+. Several tree species showed variation in dominance and density across the community types. Rank correlation of soil with vegetation ordination axes revealed greater correlation along Axis 1 than higher order axes. Soil Cl- was observed to markedly correlate with hyperspace locations of Nypa fruticans, Avicennia africana, Rhizophora mangle and Acrostichum aureum communities. Soil classification showed that several soil properties could serve as indicators for community type differentiation. Additional environmental factors influencing mangrove distribution were inferred from the ordination patterns

The performance and distribution of species along soil salinity gradients of mangrove swamps in southeastern Nigeria

Based on periodic soil salinity measurements direct gradient analysis procedures were used to relate the performance and distribution of mangrove swamp species to salinity gradients. Variations in soil salinity were due to distance from the coast, tidal incursions and freshwater inputs. All overstorey species showed statistically significant negative correlations with salinity while most ground layer species were positively correlated with the same factor. Based on ecological group classification, no species was found to occur on the highest values of soil salinity. There were overlapping range of occurrences and ecological optima for most species along the gradients

Domestic Solid Waste Management in a Rapidly Growing Nigerian City of Uyo

This paper investigated domestic waste management procedures in the fast growing Nigerian city of Uyo. The city of Uyo was demarcated into three Zones A, B and C respectively representing high, medium and low income residential areas. The quantity and classes of waste generated in the city were measured. Using questionnaire, relevant information on waste storage, collection, disposal and re-cycling were obtained. The result showed a marked variation in domestic waste types generated across the three zones reflecting the income levels of the inhabitants. The highest total weights were generated in the middle income zone while the lowest values were reported in the low income zone where waste storage in polythene bags was also common. Daily collection of waste was confirmed in the high income zone whereas waste littering characterized by overfilled receptacles was common in the middle and the low income zones respectively. Waste dumping in drain/gutters was the major feature of zones B and C and because less reusable materials formed a greater part of the waste generated in this zone, the activities of scavengers dropped compared to Zone A where more reusable waste was generated. A number of recommendations were made to help improve domestic waste management in the city. These included, among others, the closure of all waste dump sites without liners and the establishment of sanitary landfills for the city in addition to encouraging both private agencies and informal labour waste collection activities

SOCIO-ECONOMIC DEVELOPMENT OF NIGERIA AND YOUTH EMPLOYMENT IN 21 ST CENTURY: IMPLICATION FOR AKWA IBOM STATE

ABSTRAC

Relationships between vegetation gradients and soil variables of mangrove swamps in southeastern Nigeria

The vegetation and soils of mangrove swamps were studied in order to determine the relationship between species variation and soil variables. The basic premise was that the vegetation and the soils are multivariate and could be viewed in terms of gradients. Principal components analysis, an eigenvector multivariate analytical technique, was used in the interpretation of the structure within the correlation matrix of the vegetation and soil data. The principal components analysis indicated the first four components of the soil system as: salinity (complex hydrochemical gradient); nutrient gradient; soil moisture gradient; and substrate texture gradient. The first four components of the vegetation system were indicated as: competition gradient; adaptation gradient; residual competition gradient; and site preference gradient. The soil salinity gradient was negatively correlated with vegetation competition and adaptation gradients (r= - 0.38; r= - 0.35), while the nutrient gradient was positively correlated with the residual competition gradient (~0.56). It was observed that non-mangroves were more sensitive to soil nutrient levels than true mangrove species