Spatial Variation of Carbon Stock Density in Guinea Savanna Landscape of Niger State, Nigeria

Abstract

The dearth of data on quantitative carbon stock measurements in the savanna ecological zones coupled with uncertainties associated with extrapolated biome average values, have resulted in a significant gap in the carbon stock of savanna landscapes. The study aimed to estimate and compare carbon stock density of plant communities in the guinea savanna landscape of Niger State, Nigeria. The research methodology featured field survey inventory, biometric measurements and laboratory analysis. Eight plant communities were inventoried based on eleven parameters of their structure and composition. Carbon stock was measured from six major pools (above ground tree, undergrowth, dead wood, litter, root and soil). Both ANOVA and t-test statistics revealed that there were significant differences in all parameters measured between pairs of plant communities and over the entire study area. The mean carbon stocks of plant communities, in decreasing order, were Savanna woodland (127.30 Mg ha-¹), Riparian Forest (116.31 Mg ha-¹), Tree Savanna (114.44 Mg ha-¹), Scrubland (111.47 Mg ha-1), Grassland (106.72 Mg ha-1), Agroforestry (78.53 Mg ha-¹), Old Fallow Land (72.50 Mg ha-¹), and Recent Fallow land (66.31 Mg ha-¹). The ANOVA indicated significant spatial variability in carbon stock across the landscape (where F(7,37) =160.69, P<0.01). Similarly, the student t–test revealed significant differences in carbon stock between virtually all pairs of plant communities. This study provides more accurate estimations of carbon stock in Guinea savanna ecological area of Niger state, Nigeria. These estimates are useful benchmark against which future estimates can be compared, and sets a baseline for calculating changes in carbon stocks over time; with a view to monitoring carbon sources and sinks in relation to climate change mitigation potential
of the Savanna ecological landscapes.