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Causes and Perceptions of Environmental Change in the Mangroves of Rufiji Delta, Tanzania: Implications for Sustainable Livelihood and Conservation
Stockholm University, Faculty of Science, Department of Physical Geography.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Mangroves are ecosystems with enormous ecological importance, supporting both terrestrial and marine food webs. They provide ecosystem services (e.g. food, medicines, fuel, constructing material) to communities near and far. Despite their importance, mangrove areas are facing numerous threats. Based on neo-Malthusian narratives, population growth is an alleged main cause of mangrove degradation, especially in developing countries. This thesis investigates the Rufiji Delta mangroves, from several perspectives including: recent history, present condition, use of land and other resources, as well as actual and potential impacts of government policies and management on mangrove conservation and for the local communities. Of special interest is the examination of multiple, and often diverging, perceptions concerning these variables and processes. Both qualitative and quantitative methods have been used. Interviews were conducted with relevant stakeholders. Analysis of census data (1957–2012), to ascertain population trends in the Delta, spans the pre- and post-Ujamaa villagization programme. Old maps were scanned and geo-referenced in GIS to compare administrative units between successive censuses. Synthetic Aperture Radar (SAR) imagery, spanning from 1994 to 2010, was explored for analysis of mangrove dynamics and stand structure. The analysis of population trends in the Delta revealed decreasing population in the South Delta and a low population increase in the North Delta, in comparison with neighbouring non-delta areas. This is contrary to the assumption by government authorities that the Ujamaa villagization programme instigated migration to the Delta which caused mangrove degradation. Spatio-temporal changes in mangrove area and land use, observed and confirmed by SAR imagery and field control, is part of the highly dynamic eco-hydrology and geomorphology of the delta ecosystem. While some areas have been converted to rice farms, other areas have gained in mangrove coverage. Overexploitation of mangroves occurs, primarily by external actors, and both local communities and representatives of government authorities ascribe this to lack of financial and human resources to enforce current laws and regulations. Ever since the Rufiji mangrove forest was declared as a forest reserve in 1898, it has been a legal quagmire, with legally established village land within a state forest where human habitation is prohibited by law. This thesis explores management approaches that will embrace conservation with sustainable development. That can only be achieved when local communities are legally recognized as inhabitants and important stakeholders in the conservation of the Delta. A conservation approach that removes land tenure uncertainty among the local communities and takes into consideration the dynamic nature of the Delta must be devised for the Rufiji mangroves.

Place, publisher, year, edition, pages
Stockholm: Department of Physical Geography, Stockholm University , 2016. , 39 p.
Series
Dissertations from the Department of Physical Geography, ISSN 1653-7211 ; 54
National Category
Physical Geography
Research subject
Physical Geography
Identifiers
URN: urn:nbn:se:su:diva-128074ISBN: 978-91-7649-389-2 (print)OAI: oai:DiVA.org:su-128074DiVA: diva2:912591
Public defence
2016-05-13, William-Olssonsalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Sida - Swedish International Development Cooperation Agency
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript. Paper 3: Manuscript.

Available from: 2016-04-20 Created: 2016-03-17 Last updated: 2017-02-23Bibliographically approved
List of papers
1. Landscape processes, resource use and conservation ideologies in the Rufiji Delta, Tanzania – An examination of population and degradation narratives
Open this publication in new window or tab >>Landscape processes, resource use and conservation ideologies in the Rufiji Delta, Tanzania – An examination of population and degradation narratives
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Based on the Neo-Malthusian narrative, the Ujamaa villagization program that took place in Tanzania between 1967 and 1974 is alleged to have caused considerable degradation to the mangroves of the Rufiji Delta as people migrated to the Delta and cleared mangroves for rice cultivation. Using population data from the censuses of 1957 to 2012, we have examined the population trend in the Delta and its possible impact on the mangroves. The census period comprises the pre-Ujamaa and post-Ujamaa periods. Analysis of population trends in the South Delta reveals that the Ujamaa villagization program did not instigate migration to the South Delta and that population is decreasing rather than increasing. In the North Delta there was an increase in population possibly associated with the Ujamaa villagization program, but the population increase in neighboring, non-delta areas was considerably larger. The persistent neo-Malthusian narrative of population growth inevitably leading to mangrove degradation in the Rufiji Delta is thus refuted. Contrary to the assumed causes of environmental changes in the Delta, this study has shown that natural dynamics (changes in salinity, erosion and sedimentation) are responsible for the spatial/temporal changes that determines when and where rice is cultivated and when and where mangroves will thrive.

National Category
Physical Geography
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-128040 (URN)
Available from: 2016-03-16 Created: 2016-03-16 Last updated: 2016-03-23Bibliographically approved
2. The Rufiji Delta Mangroves – Conservation with or without people?
Open this publication in new window or tab >>The Rufiji Delta Mangroves – Conservation with or without people?
(English)Manuscript (preprint) (Other academic)
Abstract [en]

To sustain and develop natural resource use, including local food provisioning, is often at odds with ambitions to conserve valuable ecosystems. In the state-owned Rufiji Delta Mangrove forest reserve, Tanzania, the presence of registered villages with land certificates is a source of friction between the government and the Delta communities. We have analysed the government’s conservation ambitions and the local land use situation from a land sparing–land sharing perspective. In addition, we have compared the context of the Rufiji Delta with other case studies where conservation with sustainable development has been tried, to analyse the potential for joint conservation efforts by the Delta communities and the government. Currently, the land use within and in the vicinity of the Rufiji mangroves, constitutes a non-formalised land sharing system. However, the government ambitions are to protect the entire mangrove ecosystem from human activities, i.e. a land sparing approach that cannot be effectuated without massive evictions. The government perceives local communities as intruders degrading the mangroves, while the local communities are highly suspicious of the government’s conservation intentions. A narrow ecosystem approachto conservation hinders understanding between the two stakeholders, and may prove to be inadequate to explain and allow for natural ecosystem dynamics. Current Tanzanian participatory approaches towards forest conservation cannot be implemented without being modified to accommodate the specific nature of the Rufiji Delta. Community Based Forest Management is practiced on village land and not applicable to state-owned forests. Joint Forest Management involves local communities in the management of a state forest but people reside outside the forest, which is contrary to the situation in the Rufiji Delta. A new participatory approach that removes land tenure uncertainty must be devised if conservation with sustainable development is to be achieved in the Rufiji Delta. Opportunities for successful conservation will increase by applying a wider landscape approach.

National Category
Physical Geography
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-128041 (URN)
Available from: 2016-03-16 Created: 2016-03-16 Last updated: 2016-03-23Bibliographically approved
3. Multi-decadal L-band SAR observations of the Mangrove forests of the Rufiji Delta
Open this publication in new window or tab >>Multi-decadal L-band SAR observations of the Mangrove forests of the Rufiji Delta
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Mangroves are important habitats that face a range of threats, natural and anthropogenic. Synthetic aperture radar (SAR) images from 1994 to 2010 have been used to identify systematic changes in mangrove forest vegetation in the Rufiji Delta, Tanzania. The mangrove forest is a Forest Reserve and is protected from large scale exploitation, though there are settlements within the reserve. A dataset of five L-band SAR images spanning a 16-year time period was processed to identify spatio-temporal changes in mangrove forest extent and composition. SAR signatures are related to changes in water budget. The image data show minor expansion in cultivated land along the margins of established communities in the delta. Thinning of mangroves is detected on higher ground whilst along creeks and river channels SAR backscatter indicates an increase in biomass. Sea level height is found to exert a stronger influence on backscatter than minor differences in seasonality. Despite inaccuracies in older SAR images SAR time series are shown to provide valuable data on the spatio-temporal dynamics of East African mangrove forests.

National Category
Physical Geography
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-128042 (URN)
Available from: 2016-03-16 Created: 2016-03-16 Last updated: 2016-03-23Bibliographically approved
4. L-Band Polarimetric Target Decomposition of Mangroves of the Rufiji Delta, Tanzania
Open this publication in new window or tab >>L-Band Polarimetric Target Decomposition of Mangroves of the Rufiji Delta, Tanzania
2016 (English)In: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 8, no 2, UNSP 140Article in journal (Refereed) Published
Abstract [en]

The mangroves of the Rufiji Delta are an important habitat and resource. The mangrove forest reserve is home to an indigenous population and has been under pressure from an influx of migrants from the landward side of the delta. Timely and effective forest management is needed to preserve the delta and mangrove forest. Here, we investigate the potential of polarimetric target decomposition for mangrove forest monitoring and analysis. Using three ALOS PALSAR images, we show that L-band polarimetry is capable of mapping mangrove dynamics and is sensitive to stand structure and the hydro-geomorphology of stands. Entropy-alpha-anisotropy and incoherent target decompositions provided valuable measures of scattering behavior related to forest structure. Little difference was found between Yamaguchi and Arii decompositions, despite the conceptual differences between these models. Using these models, we were able to differentiate the scattering behavior of the four main species found in the delta, though classification was impractical due to the lack of pure stands. Scattering differences related to season were attributed primarily to differences in ground moisture or inundation. This is the first time mangrove species have been identified by their scattering behavior in L-band polarimetric data. These results suggest higher resolution L-band quad-polarized imagery, such as from PALSAR-2, may be a powerful tool for mangrove species mapping.

Keyword
mangroves, synthetic aperture radar, polarimetry, ALOS PALSAR, deltas, Rufiji, L-band
National Category
Physical Geography
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-128044 (URN)10.3390/rs8020140 (DOI)000371898800035 ()
Available from: 2016-03-16 Created: 2016-03-16 Last updated: 2017-11-30Bibliographically approved
5. Biofuel potential and land availability: The case of Rufiji District, Tanzania
Open this publication in new window or tab >>Biofuel potential and land availability: The case of Rufiji District, Tanzania
2014 (English)In: Journal of Ecology and the Natural Environment, ISSN 2006-9847, E-ISSN 2006-9847, Vol. 6, no 11, 389-397 p.Article in journal (Refereed) Published
Abstract [en]

Africa’s attractiveness to potential biofuel investors is based on the assumption that there is plenty of unused land available for investment in different countries of the continent. However, their postulations are not based on any concrete studies about land availability at country, regional or local level. This study investigates land availability for potential biofuel investment at the local level, using Rufiji district in Tanzania as a case study. We have analyzed different land cover/land use types and separated them into areas of potential biofuel investment and areas where biofuel investment is not possible by a process of elimination. The results suggest that land availability is inadequate to meet the needs of biofuel investors. The land assumed to be unused or underutilized by biofuel investors is either part of the fallow system or used to harvest natural resources and for other traditional uses. Expropriating the assumed idle land will adversely impact on the livelihoods of the local communities.

Keyword
Biofuel investment, Land available, Rufiji District
National Category
Other Earth and Related Environmental Sciences
Research subject
Physical Geography
Identifiers
urn:nbn:se:su:diva-114177 (URN)
Funder
Sida - Swedish International Development Cooperation Agency
Available from: 2015-02-23 Created: 2015-02-23 Last updated: 2017-12-04Bibliographically approved

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