Vegetation ecology of a woodland-savanna mosaic in central Benin (West Africa) [Elektronische Ressource] : ecosystem analysis with focus on the impact of selective logging / vorgelegt von Bettina Orthmann

Bettina Ortmann

Informations

• Publié par: universitat_rostock
• Publié le: 01 janvier 2005
• Nombre de lectures: 39
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Vegetation ecology of a woodland-savanna mosaic in central Benin (West Africa):
Ecosystem analysis with a focus on the impact of selective logging


Dissertation
zur
Erlangung des akademischen Grades
Doctor rerum naturalium (Dr. rer. nat.)
der Mathematischen-Naturwissenschaftlichen Fakultät
der Universität Rostock






vorgelegt von
Bettina Orthmann, geb. am 13.07.1972 in Paderborn
aus Rostock

Rostock, 01.04.2005



















Gutachter:
Prof. Dr. Stefan Porembski
Prof. Dr. Martin Diekmann
Prof. Dr. Rüdiger Wittig

Tag der Verteidigung: 11.07.2005
Contents
Contents
Contents .......................................................................................................................................i
List of Figures............................................................................................................................iv
List of Tables .............................................................................................................................vi
1 Introduction.........................................................................................................................1
1.1 Ecosystem analysis.....................................................................................................3
1.1.1 Vegetation composition and classification .........................................................3
1.1.2 Vegetation structure............................................................................................4
1.1.3 Environmental parameters and vegetation..........................................................5
1.2 Impact of selective logging on the woodland-savanna mosaic ..................................6
2 Study site............................................................................................................................8
2.1 Climate........................................................................................................................9
2.2 Geology, hydrology, and pedology ..........................................................................10
2.3 Vegetation.................................................................................................................12
2.4 Human impact on the woodland-savanna mosaic ....................................................13
2.4.1 Pastoralism and grazing regime........................................................................13
2.4.2 Fire....................................................................................................................14
2.4.3 Short history of logging activities in the Upper Ouémé Valley .......................15
3 Methods............................................................................................................................16
3.1 Sampling design........................................................................................................16
3.1.1 Site selection of relevé plots.............................................................................16
3.1.2 Site selection of gap plots.................................................................................19
3.1.3 Plot design of relevé and gap plots ...................................................................19
3.2 Sampling of vegetation data in relevé and gap plots ................................................20
3.2.1 Identification of species....................................................................................20
3.2.2 Sampling of tree layer data...............................................................................21
3.2.3 of herb layer data..............................................................................22
3.2.4 Sampling of data on seedlings and saplings of woody species ........................23
3.3 Sampling of data on environmental parameters in relevé and gap plots ..................23
3.3.1 Soil....................................................................................................................23
i Contents
3.3.2 Microclimate.....................................................................................................24
3.3.3 Fire....................................................................................................................25
3.3.4 Topographical position.....................................................................................25
3.4 Survey of logging history and intensity....................................................................25
3.5 Data analysis.............................................................................................................26
3.5.1 Tabular comparison of vegetation data.............................................................26
3.5.2 Statistical analysis.............................................................................................26
3.5.2.1 Univariate data analysis................................................................................27
3.5.2.2 Multivariate data analysis.............................................................................28
4 Results..............................................................................................................................32
4.1 Floristic characteristics of the relevé plots ...............................................................32
4.1.1 Tabular comparison..........................................................................................32
4.1.1.1 Tree layer......................................................................................................32
4.1.1.2 Herb layer.....................................................................................................34
4.1.2 Multivariate ordination.....................................................................................37
4.1.2.1 Tree layer38
4.1.2.2 Herb layer41
4.1.2.3 Tree and herb layer – Bas fonds relevé plots excluded ................................42
4.2 Structural characteristics of vegetation types ...........................................................45
4.2.1 Tree layer..........................................................................................................45
4.2.2 Herb layer.........................................................................................................49
4.3 Environmental parameters of vegetation types.........................................................51
4.3.1 Microclimate.....................................................................................................51
4.3.2 Fire....................................................................................................................54
4.3.3 Topography and soil .........................................................................................55
4.3.4 Correlation between environmental parameters ...............................................59
4.4 Relation of species data and environmental parameters...........................................60
4.4.1 Significance of environmental parameters – model selection procedure .........61
4.4.2 Variance partitioning: vegetation types versus environmental parameters ......64
4.5 Logging history and intensity ...................................................................................66
4.6 Comparison between gaps and vegetation types ......................................................67
4.6.1 Environmental parameters................................................................................67
4.6.2 Species data of the herb layer ...........................................................................69
4.6.3 Seedlings and saplings of woody species .........................................................70

ii Contents

5 Discussion.........................................................................................................................75
5.1 Classification of vegetation types and floristic characteristics.................................75
5.2 Structural characteristics of vegetation types ...........................................................77
5.3 Environmental parameters and vegetation................................................................81
5.3.1 Vegetation types...............................................................................................81
5.3.2 Vegecomposition....................................................................................84
5.4 Impact of selective logging on the woodland-savanna mosaic ................................88
Summary...................................................................................................................................93
Zusammenfassung ....................................................................................................................95
References.................................................................................................................................97
Acknowledgements.................................................................................................................116
Appendix....................................