Forest management options for carbon stock and soil rehabilitation under Chilimo dry afro ...

293 Pages·2015·14.43 MB·English

by  Mehari Alebachew Tesfaye

;

Forest management options for carbon stock and soil reha-

bilitation in Chilimo dry afro -montane forest, Ethiopia

DOCTORAL THESIS

Mehari Alebachew Tesfaye

February, 2015

Palencia, Spain
Forest management options for carbon stock and soil rehabilitation in Chilimo dry afro-montane forest, Ethiopia
ESCUELA TĖCNICA SUPERIOR DE INGENIERĺAS AGRARIAS

INSTITUTO UNIVERSITARIO DE INVESTIGACIȮN EN GESTIȮN
FORESTAL SOSTENIBLE

TESIS DOCTORAL:

FOREST MANAGEMENT OPTIONS FOR CARBON STOCK AND
SOIL REHABILITATION IN CHILIMO DRY AFRO-MONTANE
FOREST, ETHIOPIA

Presentada por Mehari Alebachew Tesfaye por optar al grado de doc-
tor por la Universidad de Valladolid

Dirigida por:

Dr. Andrés Bravo Oviedo
Dr. Felipe Bravo Oviedo
Forest management options for carbon stock and soil rehabilitation in Chilimo dry afro-montane forest, Ethiopia

Dedication

This thesis is dedicated to my beloved children

(Kidus Mehari and Yohanan Mehari)
Tesfaye (2015)
Table of contents
Contents
LIST OF ORIGINAL WORKS .................................................................................................................................. 1
ACKNOWLEDGEMENTS ...................................................................................................................................... 3
ABSTRACT ....................................................................................................................................................... 5
RESUMEN ........................................................................................................................................................ 9
1. INTRODUCTION ....................................................................................................................................... 13
1.1. African forest resources, the case of Ethiopia ....................................................................................... 13
1.1.1. Ethiopian forests ............................................................................................................................ 15
1.3. Carbon stock in tropical and Ethiopian forests ..................................................................................... 20
1.4. Chilimo dry afro-montane forest of Ethiopia ........................................................................................ 23
1.5. Forest management tools available for African tropical forests ........................................................... 26
2. OBJECTIVES OF THE THESIS ................................................................................................................. 27
2.1. Aims and specific objectives................................................................................................................. 27
2.2. Conceptual model ................................................................................................................................. 29
3. MATERIAL AND METHODS ........................................................................................................................... 33
3.1. Study sites ............................................................................................................................................. 33
3.2. Experimental design and sampling ....................................................................................................... 34
3.3. Data gathering ....................................................................................................................................... 35
3.3.1. Tree data ........................................................................................................................................ 35
3.3.2. Biomass data .................................................................................................................................. 37
3.3.3 Coarse wood debris and stump data collection .............................................................................. 38
3.3.4. Soil data (study I and study III) ..................................................................................................... 38
3.3.5. Wood density and carbon concentration (study V) ........................................................................ 39
3.4. Laboratory methods .............................................................................................................................. 40
3.4.1. Soil analysis ................................................................................................................................... 40
3.4.2. Wood density and carbon concentration........................................................................................ 41
3.5. Statistical analysis ................................................................................................................................. 42
3.5.1. Mixed models ................................................................................................................................. 42
3.5.2. General linear models .................................................................................................................... 43
3.5.3. R- software ..................................................................................................................................... 44
4. RESULTS ........................................................................................................................................................ 47
4.1. Performance and soil condition of selected species in degraded highlands of Ethiopia (study I) ........ 47
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Forest management options for carbon stock and soil rehabilitation in Chilimo dry afro-montane forest, Ethiopia

4.2. Biomass model, partitioning and comparison (study II) ....................................................................... 54
4.3. SOC and SON concentration and bulk density along elevation, land use and species (study III) ........ 55
4.4. Stand density management model evaluation and fitting (study IV) .................................................... 57
4.5. Carbon concentration and wood density for five most commonly tree species (study V) .................... 58
5. DISCUSSION .................................................................................................................................................. 61
5.1. Performance and soil condition of selected species in degraded highlands of Ethiopia (study I) ........ 62
5.2. Biomass model, partitioning and comparison (study II) ....................................................................... 64
5.3. SOC and SON concentration and bulk density along elevation gradient, land use and species (study
III) ................................................................................................................................................................ 65
5.4. Stand density management model evaluation and fitting (study IV) .................................................... 68
5.5. Carbon concentration and wood density for five most commonly tree species (study V) .................... 68
6. GENERAL CONCLUSIONS .............................................................................................................................. 73
6. CONCLUSIONES GENERALES ........................................................................................................................ 75
REFERENCES ..................................................................................................................................................... 77
Sas codes used for data analysis ................................................................................................................ 102
Study I ............................................................................................................................................................ 127
Selection of tree species and soil management for simultaneous fuelwood production and soil rehabilitation
in the Ethiopian Central Highlands ................................................................................................................ 127
Abstract ...................................................................................................................................................... 127
Introduction ................................................................................................................................................ 128
Material and Methods ................................................................................................................................ 129
Results ........................................................................................................................................................ 135
Discussion................................................................................................................................................... 148
Conclusions ................................................................................................................................................ 152
Acknowledgements .................................................................................................................................... 153
References ................................................................................................................................................. 153
Study II ........................................................................................................................................................... 163
Aboveground biomass equations for sustainable production of fuel wood in a native dry tropical afro-
montane forest of Ethiopia ............................................................................................................................ 163
Abstract ...................................................................................................................................................... 163
Introduction ................................................................................................................................................ 164
Material and Methods ................................................................................................................................ 166
Results ........................................................................................................................................................ 173
Discussion .................................................................................................................................................. 180
Tesfaye (2015)
Conclusions ................................................................................................................................................ 182
Acknowledgements .................................................................................................................................... 183
References .................................................................................................................................................. 183
Study III .......................................................................................................................................................... 191
Impact of changes in land use, species and elevation on soil organic carbon and total nitrogen in Ethiopian
Central Highlands ........................................................................................................................................... 191
Abstract ...................................................................................................................................................... 191
Introduction ................................................................................................................................................ 192
Material and Methods ................................................................................................................................ 194
Results ........................................................................................................................................................ 200
Discussion .................................................................................................................................................. 210
Conclusions ................................................................................................................................................ 214
Acknowledgements .................................................................................................................................... 214
References .................................................................................................................................................. 215
Study IV .......................................................................................................................................................... 223
Stand density management diagram for Chilimo dry afro-montane forest using species proportion in
Central Highlands of Ethiopia ........................................................................................................................ 223
Abstract ...................................................................................................................................................... 223
Introduction ................................................................................................................................................ 224
Material and Methods ................................................................................................................................ 225
Results ........................................................................................................................................................ 230
Discussion .................................................................................................................................................. 239
Conclusions ................................................................................................................................................ 241
Acknowledgements .................................................................................................................................... 241
References .................................................................................................................................................. 242
Study V ........................................................................................................................................................... 247
Variation in carbon concentration and wood density for five most commonly grown tree species in Ethiopia
....................................................................................................................................................................... 247
Abstract ...................................................................................................................................................... 247
Introduction ................................................................................................................................................ 248
Material and Methods ................................................................................................................................ 250
Results ........................................................................................................................................................ 253
Discussion .................................................................................................................................................. 262
Conclusions ................................................................................................................................................ 264
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Forest management options for carbon stock and soil rehabilitation in Chilimo dry afro-montane forest, Ethiopia

Acknowledgements .................................................................................................................................... 265
References .................................................................................................................................................. 265
Photographs ................................................................................................................................................... 271

Forest management options for carbon stock and soil rehabilitation in Chilimo dry afro-montane forest, Ethiopia

LIST OF ORIGINAL WORKS

This thesis is based on five original works which are presented in the text with Roman nu-
merals (I, II, III, IV, V) i.e. one published, one accepted with major revision, one submitted and two
manuscripts.

I. Tesfaye, A. Mehari, Bravo-Oviedo, A., Bravo, F., Kidane, B., Bekele, K., Sertse, D., 2014. Selec-
tion of tree species and soil management for simultaneous fuelwood production and soil rehabili-
tation in the Ethiopian Central Highlands. Land Degradation & Development (2014). Doi:
10.1002/idr/.2268 (Wiley online library.com).

II. Tesfaye, A. Mehari, Ruiz-Peinado, R., Bravo-Oviedo, A., Bravo, F., 2014. Aboveground bio-
mass equations for sustainable production of fuelwood in a native dry tropical afro-montane for-
est of Ethiopia. Submitted to Annals of Forest Science, Springer.

III. Tesfaye, A. Mehari, Bravo, F., Ruiz-Peinado, R., Pando, V., Bravo-Oviedo, A., 2015. Impact of
changes in land use, species and elevation on soil organic carbon and total nitrogen in Ethiopi-
an Central Highlands. Accepted with major revision, Geoderma, Elsevier.

IV. Tesfaye, A. Mehari, Bravo, F., Bravo-Oviedo, A., 2015. Stand density management diagram for
Chilimo dry afro-montane forest using species proportion in Central Highlands of Ethiopia.
Manuscript.

V. Tesfaye, A. Mehari, Bravo-Oviedo, A., Bravo, F., Herrero, C., 2015. Variation in carbon con-
centration and wood density for five most commonly grown tree species in Ethiopia. A paper
presented on 28th and 29th of January 2015: IX young researchers meeting on conservation and
sustainable use of forest systems 2015, Valsaín-Segovia-Spain (Abstract published).
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