Effects Of Anthropogenic Actives On Tree Species Diversity in Gishwati Forest Reserve, Western, Rwanda

ABSTRACT The study in Gishwati forest Reserve aimed at determining the effect of anthropogenic activities on tree species diversity. Three areas within the forest were described as Disturbed Forest (DF), Natural forest (NF) and secondary forest (SF) in consideration of level of human disturbance. Data collection was done using plot sampling based on enumerating tree species (with a diameter at breast height ≥10 cm) within the forest, and observations to improve on validity and reliability of the measurement. Four transects, ranging from 2 to 3.8 km in length and cutting through the disturbed and undisturbed portions of the study were established. The distribution of species within the sample plots was determined using percentage frequency, relative density and species abundance. Shannon-Wiener diversity index (H) and Pielou’s evenness index (~ were used to characterize species diversity in the sampling area. To determine if there was significant difference in tree species diversity between the disturbed and undisturbed areas of the Forest reserve, one-way Analysis of Variance (one-way ANOVA) test using SPSS package, version 16.0 was used to find if the means are different between different areas of the forest. Analysis of data collected from the 60 sample plots in the study area, revealed that 753 individuals trees were in existence: 44 species, 43 genera and 27 families. There was a difference in number of tree species and individual trees. The results showed 31 species with 235 tree individuals in disturbed forest, 40 species with 291 tree individuals in natural forest and 30 species with 227 tree individuals in secondary forest. The results revealed also that the differences in tree canopy density and tree diversity and DBH distribution are highly significant in three area of the forest. x The results of the Shannon index (H’) indicated that the highest community diversity was discovered in Natural forest reserve defined as undisturbed part of the forest (3.45). This is foflowed by secondary part of the forest (2.75) while the last value was obtained for the disturbed part of Forest Reserve (2.7). The species diversity values obtained for the three sites were different. This showed that the anthropogenic activities have an impact on tree species diversity. Species evenness (E) results followed the same pattern as H’. The highest value 0.936(Evenness) was obtained for natural part of the Forest Reserve while 0.809 and 0.788 were obtained for secondary part of the forest and disturbed part of forest reserve respectively. Tree diversity decreased with increase of disturbances. Anthropogenic disturbances have an impact on forest structure, tree distribution and diversity. The management strategies for forest rehabilitation and tree diversity conservation should be applied in the forest reserve the restoration of tree species which are rare or that have disappeared in the study area and forest regeneration. Other approaches such as involving local communities in forest biodiversity conservation and protecting people’s livelihoods is the most appropriate strategy for sustainable management of tree diversity.

TABLE OF CONTENTS

DECLARATION

APPROVAL ii

DEDICATION iii

ACKOWLEDGEMETS

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES vW

LIST OF APPENDICES ix

ABSTRACT

CHAPTER ONE: INTRODUCTION 1

1.1 Background of the study 1

1.2 Problem statement 3

1.3 Purpose of the study 4

1.4 Research objectives 4

1.5 Research questions 4

1.6 Scope of the study 5

1.7 Significance of the study 5

CHAPTER TWO:LITERATURE REVIEW 6

2.1 Gishwati forest reserve degradation 6

2.2 Gishwati forest reserve Biodiversity 8

2.3 Anthropogenic pressure on forest biodiversity 9

CHAPTER THREE: MATERIALS AND METHODS 14

3.1 The study area 14

3.2 Research design 16

3.3 Botanical survey method 16

3.4 Estimation of diameter at breast height and Canopy cover 18

3.5 Survey of former users of the forest 18

3.6 Identification of tree species .18

3.7 Data analysis 18

3.7.1. Tree species distribution 18

3.7.2. Tree species diversity analysis 19

3.7.3 Statistical analysis 20

CHAPTER FOUR: RESULTS AND DISCUSSION 21

4.1 Tree species composition and species richness 21

4.3 Tree species distribution in Gishwati Forest reserve 25

4.5 DBH class distribution 31

4.6 Anthropogenic impacts on the tree species diversity 32

CHAPTER FIVE: CONCLUSIONS AND RECOMMENDATIONS 40

5.1 Conclusions 40

5.2 Recommendations 40

REFERENCES 43

APPENDICES 46