BIOMASS AND CARBON STOCK DENSITY OF KPASHIMI FOREST RESERVE AND ADJOINING PARKLAND AREA, NIGER STATE, NIGERIA
BIOMASS AND CARBON STOCK DENSITY OF KPASHIMI FOREST RESERVE AND ADJOINING PARKLAND AREA, NIGER STATE, NIGERIA
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Date
2016-05
Authors
JIBRIN, Abdullahi
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Abstract
Climate change, during the last decades, has increased the need for information on the amount of forest biomass and carbon stocks. The international concern for carbon emissions and sequestration assessments require adequate coverage of locally quantified carbon stocks. However, the dearth of data on quantitative biomass/carbon stock measurements coupled with the uncertainties associated with extrapolated biome average values, in tropical savannas have resulted in a significant gap in the carbon budget of Kpashimi forest reserve and adjoining parkland area. Current estimates for tropical savannas in Nigeria are based on biome average values plagued by uncertainties associated with inaccurate and incomplete measurement of forest carbon pools. Against this background, the aim of this study was to assess the biomass and carbon stock density of Kpashimi Forest Reserve and adjoining parkland area in Niger State, Nigeria. Biometric forest inventory techniques, direct biomass sampling and laboratory analysis methods were employed for data collection. Eight plant communities inventoried include Savanna Woodland, Riparian Forest, Tree Savanna, Scrubland, Grassland, Agroforestry, Old Fallow Land, and Recent Fallow land. The parameters measured include Tree Density, Species Richness, Shannon Wiener Diversity Index, Species per Plot, Tree Crown Cover, Shrub Cover, Grass Cover, Tree Height, Diameter at Breast Height, Basal Area and Biomass. Carbon stock was measured from six major pools (above ground tree, undergrowth, dead wood, litter, root and soil). Measurement of plant community characteristics was carried out in 45 quadrat sampling plots of 500 m2. Four fixed size square frames encompassing 1m2 was used for the undergrowth (shrubs and grasses) and litter. Composite soil samples (for organic carbon) and undisturbed samples (for bulk density) were taken from each of the 1m2 subplot quadrants at two depths (0-15cm and 15-30cm). Descriptive statistics was used to summarize the data while variation in carbon stock densities among plant communities across study area were tested by use of analysis of variance (ANOVA). The student’s t –test was used to test for differences in carbon stock and vegetation parameters between pairs of vegetation communities and specifically between the forest reserve and parkland, while stepwise multiple regression analysis was used in identifying key predictors of carbon stock in the study area.
Results obtained revealed that, ecologically dominant tree species in the study area in descending order are Vitalleria paradoxa, Irvingia gabonensis, Parkia biglobosa, Anogeissus leiocarpus, Pterocarpus erinaceous, Detarium microcarpum, Prosopis africana, Danellia oliveri, and Afzelia Africana; which together account for about 65.2 % of total species. The distribution of structural attributes of tree species height, Diameter at Breast Height (DBH), basal area, and biomass produced a reverse “J” shaped curves which shows that the area is dominated by regenerating saplings and seedlings. The Shannon-Wienner index values obtained in this study lie between 2.30 and 2.78; which indicates that the study area is generally characterized by medium biodiversity. The mean tree stand density (stem per hectare) was 244-935 stems/ha. Tree crown cover is in the range of 13- 55 %. The mean tree height in the study area was 17.1 metre. The mean tree diameter at breast height (DBH) recorded in the study area was 25.62 cm. 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, are 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 indicates significant differences in carbon stock across the respective
plant communities; where F(7,37) =160.69, P<0.01. Similarly, the student t–test
revealed that there is significant difference in carbon stock density between the forest
reserve and parkland study sites where t (43) = 18.34, p < 0.001). The results also
revealed that DBH, tree density, and basal area are the best predictors of carbon stock in
the study area; with the stepwise multiple regression analysis final model being
statistically significant where F(3,41) = 173.9, P <0.05. The dominance of regenerating
saplings implies that there is tremendous capacity for the study area to store carbon and
act as carbon sink if properly managed. The study recommends carbon offset trading
projects by local communities, which will provide window of opportunities for
accessing carbon credits through the Clean Development Mechanism tool of the Kyoto
Protocol under the United Nations Framework Convention on Climate Change.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA.
IN PARTIAL FULFILMENT OF THE REQUIREMENT
FOR THE AWARD OF A
DOCTOR OF PHILOSOPHY DEGREE IN GEOGRAPHY
DEPARTMENT OF GEOGRAPHY, FACULTY OF SCIENCE,
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
Keywords
BIOMASS,, CARBON STOCK DENSITY,, KPASHIMI FOREST RESERVE,, AREA,, NIGER STATE,, NIGERIA