ABSTRACT

This research on assessment of land use/land cover change and floristic composition of Kuwanka Banza Forest Reserve in Kebbi State was carried out to determine percentage change and extent of forest cover of the Reserve area between 1984 and 2013, the current land uses in the forest area as well as the distribution and abundance of woody species. Remote sensing techniques were used in this study, where 1984 and 2013 landsat imagries were processed and analyzed within the Idrissi and ArcGIS environments. With maximum likelihood supervised classification method preceded by unsupervised classification and ground truthing, eight classes of land use type namely rocky/bare surface, sparse grassland, dense grassland, fallow/cultivation, scrubs land, shrub land, forest and water were determined at 91% degree of classification accuracy. Descriptive statistics was used to analyse the changes between both dates. Results showed that between 1984 and 2013 rocky/bare surface expanded by 66%, sparse grassland decreased by 4%, dense grassland expanded by 11%, fallow cultivation expanded by 15%, scrub land reduced by 81% between 1984 and 2013, shrub land also reduced by 60% from 1984 to 2013, forest increased by 86% from 1984 to 2013 and water increased to 26%. Four sample plots each measuring 100x100m were randomly selected within the forest reserve and woody species found were enumerated by Point Centered Quarter Method (PCQ). A total of 331 woody species were encountered in the Reserve, belonging to twenty species, genera and 11 families. Caesalpiniaceae family had the highest number of five species in five genera, followed by combretaceae with three species belonging to three different genera. Families Sterculiaceae, Annonaceae, Sapotaceae, Mimosaceae, Meliaceae, Aselepiadeceae and Eblepiadeceae had one species each, while family Fabaceae had three species of Prosopis. Detarium microcarpium had the highest relative density and dominance of 19% and 21.49%, followed by Terminalia avicenoides with 18% an 20% respectively and the least was Lannea acida having 0.6% and 0.7% respectively. Shannon’s diversity index was 2.41, species evenness (EH) stood at 0.12, and species richness (d) was 1.09. The study concluded that the area will continue to undergo forest degradation in the face of human activities without effective forest management. Public enlightenment, tree planting, establishment of cattle grazing and employment of more forest guards for improved forest management are recommended

x

CHAPTER ONE

1.0         INTRODUCTION

1.1         Background of the Study

Plants life is of interest to many scientists and researchers because it plays an important role in the interconnected system of life on earth of which vegetation is part (GBA, 1995). Vegetation provides food, shelter, habitat and a number of other services to human beings. Plants are able to derive energy directly from the sun and produce carbohydrates by photosynthesis upon which all other biotic forms depend directly or indirectly. Trees are such vital components of the ecosystem that have productive, protective and recreative functions. They control soil erosion, stabilize regional and global climates, serve as carbon sink and act in pollution control (Adamu, 2006)

Species diversity refers to the variety of species within a community. It is the number of the different species present in an area. Species richness is essentially a measure of the number of species in a defined sampling unit. It is the basic component of diversity of any community, while species evenness refers to relative abundance or proportion of individuals among the species. The distribution and abundance of different tree species over a landscape is what constitutes diversity in respect of tree species (Tripathi, 2009).

Nigeria has the highest rate of deforestation in the world. Between 1990 and 2000, Nigeria lost an average of 409,700 hectares of forest every year equal to an average annual deforestation rate of 2.38%. Between 2000 and 2005 the country lost 55.7% of its primary forests, and the rate of forest change increased by 3.12% per annum. Forest has been cleared through logging, timber export, subsistence agriculture and notably the collection of fuelwood which remains problematic in Western Africa (FAO, 2005).

1

The combination of extremely high deforestation rates, increased temperatures and decreasing rainfall are all contributing to the desertification of the country.

1.2         Statement of Problem

As natural vegetation changes in an area, degrades in structure and composition, the species associated with it also change, hence, protecting and restoring endangered ecosystem may be a more efficient way to protect species than managing them one by one (Noss et al., 1995). Kuwanka Banza Forest Reserve established in 1959 in Kebbi State, is one of the forest reserves facing serious encroachment and exploitation. Some indigenous trees and wildlife species are getting endangered due to over exploitation, bush burning, uncontrolled grazing and indiscriminate felling of trees and farming activities (Atiku, 2008).

There is also a problem of identifying what areas of forest reserve should be for conservation and those for production. With the availability of modern technologies, proper land use can be identified, and reservation of forest either for production, protection or conservation purposes can be efficiently decided upon (Adamu, 2006).

On the global scale, the total net change in vegetation between 1990 to 2000 is estimated at 8.9 million hectares per year equivalent to a loss of 0.22% of the forest area. Between 2000 and 2005, it is estimated at 7.3 million hectare per year, equivalent to a loss of 200 km2 of forest per year (FAO, 2006). Lack of strong conservation ethics, law enforcement, corruption and extreme poverty, lead to severe encroachment. Illegal exploitation of forest tree resources has also resulted in depletion of biodiversity of the existing forests. This has excessively exposed most of the soil surface to solar radiation, and this is too critical as trees depend on soil to supply basic nutrients, water and oxygen and for support (TFF, 2007).

2

Lack of information about the present status of most reserved areas in terms of species composition makes management difficult, knowing the available forest tree species composition will aid suggesting appropriate silvicultural treatments that will enhance productivity and maximum protection of the environment (TFF, 2007).

Satellite image and analysis and Geographical Information System are rapidly advancing technologies that require low forest inventory with medium to high accuracy (67-98%) and low or medium cost.

1.3         Justification of the Study

Vegetation as a habitat for biodiversity represents the very foundation of human existence as it supplies the most fundamental human needs of clean air, fresh water, food, medicinal plants and shelter. It also regulates climate (Alowson et al., 2001).

In Northern Nigeria all forest reserves are subjected to human activities which resulted in serious depletion and reduction of forest biomass (Bello, 2005). This study is aimed at providing base line information with regards to vegetation change of Kuwanka banza forest reserve. The study may be useful in planning economic development strategies not only for the local area but for the whole state. It could be used to change the old practice of high exploitation of forest resources by the local population so that the existing fragile` vegetation can be highly improved.

1.4         Aim and Objectives of the Study

The aim of the study is to examine the change in vegetation of Kuwanka banza Forest

Reserve, using landsat data.

Specific objectives are to:

i.                    Identify current land uses in the forest area.

3