Tree Growth and Tree Regeneration in Two East African Rain Forests as related to the Abiotic ...

198 Pages·2011·5.81 MB·English

Tree Growth and Tree Regeneration
in Two East African Rain Forests
as related to
the Abiotic Environment
after Human Disturbance
Dissertation zur Erlangung des Doktorgrades
der Naturwissenschaften (Dr. rer. nat.)
Fakultät Naturwissenschaften
Universität Hohenheim
Institut für Botanik (210)
vorgelegt von
Robert Gliniars
aus Wallasey (England)
2010
Dekan: Prof. Dr. H. Breer
1. Prüfer (Betreuer): Prof. Dr. M. Küppers
2. Prüfer (Mitberichter): Prof. Dr. A. Fangmeier
3. Prüfer: Prof. Dr. J. Steidle
Eingereicht am: 06.September 2010
Mündliche Prüfung am: 17.Dezember 2010

Die vorliegende Arbeit wurde am 02.Dezember 2010 von der Fakultät
Naturwissenschaften der Universität Hohenheim als „Dissertation zur Erlangung des
Doktorgrades der Naturwissenschaften“ angenommen.
Diese Dissertation ist auch in digitaler Form unter folgender Adresse verfügbar:
www://opus.ub.uni-hohenheim.de

Table of Contents
Table of content s i
Acronyms v
Summary 1
Zusammenfassung 3
1 Introduction 5
1.1 Characteristics of tropical rain forests 6
1.2 Tree succession and disturbance 7
1.2.1 Seedling regeneration 9
1.2.2 Stem growth 1 2
1.3 Aim of this study 1 4
2 Study Sites 17
2.1 Kakamega Forest in Kenya 1 8
2.1.1 Geography 18
2.1.2 Geology and Soils 2 0
2.1.3 Climate 2 0
2.1.4 Vegetation 22
2.1.5 Human impact 2 2
2.2 Budongo Forest of Uganda 2 3
2.2.1 Geography 23
2.2.2 Geology and Soils 2 4
2.2.3 Climate 2 5
2.2.4 Vegetation 26
2.2.5 Human Impact 2 6
2.3 Main differences between the two forests 2 7
3 Material and Methods 2 9
3.1 Study plots 2 9
3.1.1 Disturbance classification 32
3.1.2 Recording of forest stand structure and tree diversity 3 3
3.1.2.1 Hemispherical photography 3 4
3.1.2.2 Canopy parameters and light measurements 3 5
3.1.2.3 Species identification and collected material 3 5
3.1.3 Additional data on the abiotic environment 3 6
3.2 Stem growth measurements 3 8
3.2.1 Dendrometer bands 3 9
3.2.2 Selected species 4 0
3.2.3 Tree stem growth measurement 4 1
3.2.4 Stem growth rates 4 2
3.2.5 Tree phenology surveys 4 3
3.2.6 Tree age calculation 4 3
3.3 Seedling surveys 4 4
3.4 Data handling and statistics 44
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Table of Contents
3.4.1 General Statistics 4 5
3.4.2 Estimates of the actual species richness 4 5
3.4.3 α-diversity 4 6
3.4.4 β-diversity 4 6
4 Results: Kakamega Forest 4 7
4.1 Tree diversity 4 7
4.1.1 α-diversity 4 7
4.1.1.1 α-diversity as related to environmental factors 4 8
4.1.2 Effect of disturbance on β-diversity 49
4.2 Tree dynamics 5 0
4.2.1 Stem growth of all study trees 5 0
4.2.2 Stem growth of selected tree species 5 1
4.2.3 Temporal constancy of stem growth 5 2
4.2.4 Stem growth as related to phenological dynamics 5 3
4.2.5 Tree turnover 5 5
4.2.5.1 Tree age 5 5
4.2.5.2 Self-thinning and tree mortality 5 6
4.2.5.3 Balance of tree turnover 56
4.2.6 Stem growth as related to structural tree parameters 58
4.2.6.1 Between species stem growth by DBH categories 58
4.2.6.2 Between species stem growth by height categories 6 1
4.3 Forest structure as related to human disturbance 6 4
4.3.1 Effect of plot size 6 6
4.3.2 Canopy parameters 6 6
4.4 Effects of climatic factors on tree dynamics 68
4.4.1 Effect of incident precipitation and canopy throughfall on stem
growth 6 8
4.4.2 Effect of temperature on stem growth 7 1
4.4.3 Effect of climatic factors on tree phenology 7 4
4.4.4 Effect of soil parameters on tree growth 7 4
4.4.4.1 Plot scale 7 4
4.4.4.2 Tree individual scale 7 6
4.5 Tree seedling establishment 7 7
4.5.1 Tree seedling α-diversity 7 7
4.5.1.1 Tree seedling diversity as related to abiotic factors 7 8
4.5.2 Dynamics of seedlings in space and time 7 9
4.5.2.1 Seedling recruitment 79
4.5.2.2 Dynamics of seedlings as related to canopy throughfall 82
4.5.2.3 Seedling dynamics and incident precipitation 8 3
4.5.2.4 Distribution of tree seedlings as related to soil parameters 8 5
4.5.2.5 Survival of tree seedlings from initial census 8 5
5 Results: Budongo Forest 8 7
5.1 Tree diversity 8 7
5.1.1 α-diversity 8 7
5.1.1.1 α-diversity as related to environmental factors 8 8
5.1.2 β-diversity 8 8
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Table of Contents
5.2 Tree dynamics 8 9
5.2.1 Stem growth of all study trees 8 9
5.2.2 Stem growth of selected tree species 9 0
5.2.3 Temporal constancy in stem growth 91
5.2.4 Stem growth as related to phenological dynamics 9 2
5.2.5 Tree turnover 9 4
5.2.5.1 Tree age 9 4
5.2.5.2 Self-thinning and tree mortality 9 4
5.2.5.3 Balance of tree turnover 95
5.2.6 Stem growth as related to structural parameters 9 6
5.2.6.1 Between species growth by DBH categories 9 6
5.2.6.2 Between species growth by height categories 9 9
5.3 Forest structure as related to human disturbance 100
5.3.1 Canopy parameters 101
5.4 Effect of climatic factors on tree dynamics 103
5.4.1 Effect of incident precipitation on stem growth 103
5.4.2 Effect of temperature on stem growth 104
5.4.3 Effect of climatic factors on tree phenology 108
5.5 Tree seedling establishment 109
5.5.1 Tree seedling α-diversity 109
5.5.1.1 Seedling diversity as related to abiotic factors 109
5.5.2 Dynamics of seedlings in space and time 111
5.5.2.1 Seedling recruitment 111
5.5.2.2 Dynamics of seedlings as related to climatic factors 112
5.5.2.3 Distribution of seedlings as related to the abiotic environment 115
5.5.2.4 Survival of tree seedlings from initial census 115
6 Forest Comparison 117
6.1 Tree diversity and forest structure 117
6.2 Stem growth 118
6.2.1 Tree growth as related to abiotic factors 118
6.2.2 Species growth comparison 119
6.3 Seedling density as related to abiotic factors 120
7 Discussion 121
7.1 Influence of human disturbance on the two forests 121
7.1.1 Tree diversity and growth on forest scale 121
7.1.2 Different successional stages 124
7.2 Tree succession in disturbed forest sites 130
7.2.1 The pioneer-climax continuum 130
7.2.2 Role of the temporal variability of climatic factors 133
7.2.3 Role of the spatial variability of soil parameters 136
7.3 Conclusion 139
8 Acknowledgements 141
9 References 143
iii
Table of Contents
List of Figures 159
List of Tables 165
10 Appendix 171
10.1 Kakamega Forest 171
10.2 Budongo Forest 178
Erklärungen 187
Curriculum Vitae 191
iv
Acronyms
Acronyms
% circ: Relative growth
abs.: Absolute growth
ACE: Species estimator
acetate: Ammonium acetate extracted
acid: Nitric acid extracted
a.s.l.: Above sea level
B: Biso (part of Budongo Forest)
BA: Basal Area
BCFS: Budongo Conservation Field Station
BCI: Barro Colorado Island Forest
BDO: Biodiversity Observatory
BF: Budongo Forest
BIOTA: Biodiversity Monitoring Transect Analysis
BU: Buyangu Hill (part of Kakamega Forest)
C: Carbon
Ca: Calcium
CA: Campforest (part of Kakamega Forest)
CDI: Commercial Disturbance Index
CE: Crown exposure
CEC: Cation Exchange Capacity
Chao 1: Species estimator
Chao 2: Species estimator
circ.: Circumferential
Cmol: Coulomb per mole
CO: Colobus (part of Kakamega Forest)
DBH: Diameter at Breast Height
DBH max: Maximum DBH
DBH min: Minimum DBH
EA: East African herbarium in Nairboi, Kenya
EC: Electrical Conductivity
e.g.: exempli gratia
EM: Ectomycorrhiza
FD: Forest Department, Kenya
Fisher’s alpha: Diversity Index
FTEA: Flora of Tropical East Africa
ha: Hectare
Height max: Maximum height
Height min: Minimum height
v
Acronyms
HOH: Herbarium of the University of Hohenheim
IDH: Intermediate disturbance hypothesis
IM: Intermediate
indiv.: Individuals
IPav: Monthly Incident Precipitation
IP2: Summed two-monthly Incident Precipitation
IP3: Summed three-monthly Incident Precipitation
IK: Ikhuywa (part of Kakamega Forest)
IS: Isecheno (part of Kakamega Forest)
IT: Shade-Intolerant
ITCZ: Inter Tropical Convergence Zone
Jackknife 1: species estimator
Jackknife 2: species estimator
K: Potassium
KA: Kaimosi (part of Kakamega Forest)
KI: Kisere (part of Kakamega Forest)
km2 : Square kilometer
KF: Kakamega Forest
KP11: Kaniyo-Pabidi 11th compartment (part of Budongo Forest)
KWS: Kenyan Wildlife Service
LAI: Leaf Area Index
LDI: Local Disturbance Index
MA: Malava (part of Kakamega Forest)
MANOVA: Analysis of variance
MFNP: Murchison Falls National Park
Mg: Magnesium
MH: Maximum height
MHU: Herbarium of the Makerere University, Uganda
Mn: Manganese
mNN: Meter über Normalnull
N: Nitrogen
N3: Nyakafunjo 3rd compartment (part of Budongo Forest)
N4: Nyakafunjo 4th compartment (part of Budongo Forest)
N15: Nyakafunjo 15th compartment (part of Budongo Forest)
n.d.: Not determined
NFA: National Forestry Authority, Uganda
NESS: Normalized Expected Species Shared
NMDS: Non-metrical dimensional scaling
No.: Number
ODI: Overall Disturbance Index
vi