AN ASSESSMENT OF THE IMPACT OF THE GROWTH OF ZARIA ON THE SURROUNDING VEGETATION COVER
AN ASSESSMENT OF THE IMPACT OF THE GROWTH OF ZARIA ON THE SURROUNDING VEGETATION COVER
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Date
2013-02
Authors
MICHAEL, Grace Uhwache
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Abstract
Anthropogenic drivers such as urbanization and economic dependence have been a major
force shaping various landscapes. Zaria town is no exception of such landscapes. This study
is aimed at an assessment of the impact of the growth of Zaria town on the vegetation
covers of the surrounding region. The objectives were to map out and analyse the land use
and land cover of the area, derive the vegetation cover index (NDVI) from the multitemporal
data set, correlate the city expansion rate with the vegetation cover index, and
assess the current status of woody biodiversity in the study area. The study area is within
20km radius around Zaria. The first part of the study employed remote sensing and
Geographic Information System techniques to analyze the general land use/land cover of
the area using four data sets: Land sat MSS (1973), Land sat TM (1990), Land sat ETM
(1999) and NigeriaSat -1 (2009). The results of the land use/land cover analysis showed
that the built-up area expanded from 44km2 in 1973 through 69km2 in 1990 and 81km2 in
1999 to 130km2 in 2009. The cultivated land also showed a general increase trend over time
from 409km2 in 1973 to 433km2 in 2009. While the forested land showed a decrease, from
89km2 in 1973 to 63km2 in 2009. Using the NDVI results, it was found out that ‘Dense
vegetation’ (NDVI classification value of 0.51 to 0.96) decreased from 206 km2 in 1973 to
mere 37 km2 in 1990. It subsequently increased to 88 km2 in 1999 then to 134 km2 in 2009.
On the other hand, the ‘No vegetation’ (NDVI classification value of -0.95 to 0.00) steadily
increased from 1,168 km2 in 1973 to 1,736 km2 in 2009. The second part of the study
involved field survey to determine the physiognomic characteristic of tree species in the
study area. Overall, 161 tree stands belonging to 23 species were enumerated over the 25
(50 by 50 m) sample plots covered in the study. The dominant species found among others
species are Khaya senegalensis (45 trees). This was followed by Mangifera indica (26
trees), Azadirachta indica, (17 trees) and Adansonia digitata, (14 trees). When the
differences in the number of trees amongst the various land uses were subjected to analysis
of variance, the results showed highly significant value at greater than 0.05 level. It was
also noted from the field survey that, the plantation/ forest area recorded the highest
average tree stand of 23.5. This was followed by the fadama/wetlands with an average of 8
tree stand. The built-up area has an average of 7 tree stand and the cultivated lands 5. The
scrubland has the least average of 1.6 tree stand. With respect to the other vegetation
characteristics, the built-up areas, plantation/forest and the fadama/wetland have
comparatively higher mean values for tree height, DBH, biomass and basal area. The result
of ANOVA shows that the differences in most of the measured parameters of the woody
species amongst the land uses are statistically significant at 0.05 level. It was concluded
that the expansion of Zaria town posed a formidable threat to biodiversity in the region and
strategies to improve forest conservation in the region are urgently needed.
Description
A THESIS SUBMITTED TO THE POST GRADUATE SCHOOL, AHMADU
BELLO UNIVERSITY, ZARIA, IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE AWARD OF THE DEGREE OF MASTERS OF
SCIENCE. (M.Sc) ENVIRONMENTAL MANAGEMENT
FEBRUARY, 2013
Keywords
ASSESSMENT,, IMPACT,, GROWTH OF ZARIA,, SURROUNDING,, VEGETATION COVER.