biomass estimation and carbon storage in mangrove forests of tanzania by marco andrew njana a ...

192 Pages·2015·3.32 MB·English

BIOMASS ESTIMATION AND CARBON STORAGE IN MANGROVE
FORESTS OF TANZANIA

BY

MARCO ANDREW NJANA

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY
OF SOKOINE UNIVERSITY OF AGRICULTURE, MOROGORO,
TANZANIA

2015
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EXTENDED ABSTRACT

This study aimed to develop tools for biomass estimation and quantify carbon stored
in mangrove forests of Tanzania mainland. The study was carried out in four sites
along the Tanzanian coastline; Pangani, Bagamoyo, Rufiji and Lindi-Mtwara. A total
of 120 plots were measured along transects running perpendicular to sea/rivers. From
each plot, one tree was destructively sampled for aboveground biomass. Thirty
among 120 trees were sampled for belowground biomass. Data analysis was carried
out in R software. Procedures for quantification of belowground biomass for
Avicennia marina (Forssk.) Vierh, Sonneratia alba J. Smith and Rhizophora
mucronata Lam. were documented in detail. Root sampling is recommended for A.
marina and S. alba while for R. mucronata, total root excavation method may be
applied. The methods are more comprehensive than previously reported methods,
therefore they should be applied in quantification of BGB. The study found an overall
mean tree aboveground basic density of 0.60±0.00 (SE) g cm-3, 0.54 ± 0.01 (SE) g
cm-3 and 0.69 ± 0.01 (SE) g cm-3 for A. marina, S. alba and R. mucronata,
respectively. Similarly, the overall mean tree belowground basic density was 0.57 ±
0.02 (SE) g cm-3, 0.32 ± 0.01 (SE) g cm-3 and 0.53 ± 0.02 (SE) g cm-3 for A. marina,
S. alba and R. mucronata, respectively. The study also showed that basic density
varied between species, tree sizes and tree components. Accordingly, if properly
determined and applied, basic density may be useful as a conversion factor and yield
accurate biomass estimates. Otherwise they are likely to be a source of uncertainties
in biomass estimation. Common (multi-species) and species-specific above- and
belowground biomass models for the three mangrove species were developed.
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Species-specific models had better fit than common models. Evaluation of existing
biomass models on data from this study generally showed large and significant
prediction errors. Possibly this may be due to application of the models beyond data
size ranges, geographical locations, and differences in forest structure and tree
architecture. Species-specific models from this study are therefore recommended.
The use models to unrepresented species is not recommended, where necessary
however a conservativeness principle (i.e. when accuracy of estimates cannot be
achieved, the risk of over- or under-estimation should be minimised) need to be
applied. Using biomass models from this study and forest inventory data collected by
National Forest Resources Monitoring and Assessment (NAFORMA) of Tanzania,
the study quantified aboveground carbon (AGC), belowground carbon (BGC) and
total carbon (TC) stored in mangrove forests of Tanzania mainland. Results showed
that, AGC, BGC and TC were 33.5 ± 5.8 Mg C ha-1 (53% of TC), 30.0 ± 4.5 Mg C
ha-1 (47% of TC) and 63.5 ± 8.4 Mg C ha-1 respectively. Given that, mangroves of
Tanzania mainland cover approximately 158, 100 ha, a total of 10.0 millions Mg C
(i.e. 37.2 millions Mg CO e) is stored in mangrove forests of Tanzania. Results from
2
this study are essential for REDD+ initiatives and provides useful input in
management of mangrove forests in the country.
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THESIS ORGANIZATION

This thesis begins with an extended abstract followed by declaration statement,
copyrights statement, acknowledgements, and dedication. The extended abstract
summarises briefly the study objectives, approaches to sampling, main findings
conclusions and recommendations. The thesis also consists of three chapters. The
first chapter cover introduction which include, background information, problem
statement and study objectives. Conceptual and theoretical framework of the study
are also included in Chapter one. Besides chapter one includes methods sub-section
which provide descriptions of the study area, sampling, and data analysis. Chapter
two presents in summary the major findings, conclusion and recommendations.
Chapter three contains a series of original published papers (Paper 1 and Paper 3)
and publishable manuscripts (Papers 2 and Paper 4).
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DECLARATION

I, MARCO ANDREW NJANA, do hereby declare to the Senate of Sokoine
University of Agriculture that, this thesis is my own original work, done within the
period of registration and that it has neither been submitted nor being currently
submitted in any other institution.

______________________________ ____________________
Marco Andrew Njana Date
(PhD candidate)

The above declaration is confirmed by:

______________________________ ____________________
Prof. E. Zahabu Date
(Supervisor)

______________________________ ____________________
Prof. T. Eid Date
(Supervisor)
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COPYRIGHTS

No part of this dissertation may be reproduced, stored in any retrieval system or
transmitted in any form or by any means without prior written permission of the
author or the Sokoine University of Agriculture.
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ACKNOWLEDGEMENTS

First and foremost I would like to acknowledge my employer, the Tanzania Forest
Services (TFS), Ministry of Natural Resources and Tourism for granting me study
leave, without which my studies would not have been possible. The National Forest
Resources Monitoring and Assessment (NAFORMA) of Tanzania under TFS is also
acknowledged for allowing me to use the national inventory data in this study.

I am grateful to the Climate Change Impacts and Mitigation Programme (CCIAM) at
Sokoine University of Agriculture (SUA) under the cooperation between the
Government of United Republic of Tanzania and the Kingdom of Norway for
awarding me a scholarship to pursue PhD studies out of which this thesis was
produced. I am also grateful for supplementary funding by the Project ‘‘Enhancing
the Measuring, Reporting and Verification (MRV) of forests in Tanzania’’ at SUA.

Special thanks are extended to my supervisors Prof. E. Zahabu from the Department
of Forest Mensuration and Management, SUA and Prof. T. Eid from the Department
of Ecology and Natural Resources Management, Norwegian University of Life
Sciences, Norway for their intellectual and professional guidance, critical comments,
encouragement and remarkable interest in supervising this study. Above all, I am
grateful to Prof. T. Eid who joined me to the field during initial stages of data
collection, his company was very instrumental in resolving many challenges which
threatened the likelihood of implementing the endorsed research proposal.
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Special thanks are extended to Prof. R. E. Malimbwi from the Department of Forest
Mensuration and Management, SUA for his time in providing me with the needed
technical guidance, encouragement, and moral support. I would like also to gratefully
acknowledge Prof. J. Kashaigili of the Department of Forest Mensuration and
Management, SUA for his guidance during proposal development.

I am indebted to D. Mnyagi (Pangani), S. K. Nyabange (Bagamoyo), H. Mallya
(Rufiji) and M. C. Mbago (Mtwara), working for TFS, for logistical support during
field work. The field assistants including boat drivers are also acknowledged for their
hard work and audacity throughout an intensive and tiresome data collection work.

A note of gratitude also goes to Dr. J. Z. Katani, Head of the Department of Forest
Mensuration and Management at SUA for being of assistance to me throughout my
studies both as a Head of Department but also as a brother. Staff in the Department;
Mary Kiliba, Eva Mweji and Flora Fecilian, are also acknowledged for their cordial
cooperation and great company throughout my studies.

Thanks also to the Department of Ecology and Natural Resources Management,
Norwegian University of Life Sciences, Norway for hosting me when I was attending
remedial courses at the Norwegian University of Life Sciences in Norway in 2012
and also in 2014/15 when I was writing papers. Special thanks also go to Dr. Liviu.
T. Ene and Dr. Ole. M. Bollandsås both from the same Department for being so kind
and of great assistance to me during my stay in Norway.
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I am also thankful to Prof. Henrik Meilby from the Faculty of Science, University of
Copenhagen, Denmark for being very instrumental throughout my studies. His great
commitment in guiding and assisting me all the time I needed his support is very
much appreciated.

The support, love and care of my wife, Grace; daughter, Precious and son, Savio;
together with my parents and relatives, inspired me during all stages of my four year
studies. “Thank you for your unwavering support and patience during these trying
moments”. With humble submission, may I direct this catalogue of
acknowledgements to PROVIDENCE who has made it happen by taking me through
the cherishing and hard experiences of researching in the mangroves, may it be for
his glory!
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DEDICATION

This work is dedicated to God almighty; my dear wife, Grace; daughter, Precious;
son, Savio and to the memories of my late brother, Raphael.