1. SPATIAL AND TEMPORAL CHANGE OF MANGROVE FOREST OF MTONI KIJICHI, DAR ES SALAAM - TANZANIA
Presenter
Mathias Msafiri Igulu
Promotor Prof Dr Nico Koedam
Co- promotor Dr Farid Dahdouh-Guebas and
Griet Neukermans

2. Introduction Occur worldwide on tropical and sub-tropical coastlines
Mangroves ecosystems ……….
Occur worldwide on tropical and sub-tropical coastlines
Ecologically, they act as breeding, spawning, hatching and nursery grounds for marine animals
They provide construction materials, charcoal, firewood and are source for traditional medicines

3. Introduction
Mangrove ecosystems are subjected to various anthropogenic effects like
urban expansion
agriculture
tourism and
aquaculture impoundments
In Dar es Salaam City conversion of mangrove forests to residential and industrial land is the main threat
Dar es Salaam city has growth rate of 6.75% per year
Understanding mangrove dynamics may suggest conservation and management directives

4. Objectives
General objective is to examine and interpret short and long term change in mangrove of Mtoni-Kijichi
To examine vegetation structure and regeneration classes of the forest
To examine long term (decadal) change of the forest by using aerial photographs and the satellite image
To link current forest structure with the changes and propose management strategies

5. Source
Dar es salaam
Study site

6. Study site
Mtoni kijichi mangrove

7. Methodology Two methodologies Field survey (transect line plot method)
Remote sensing (aerial photographs and satellite image)

8. Study area and field methodology
Four transects were sampled, the transects are in the framework of Peri-urban mangrove forest as filters and potential phytoremediators of domestic sewage in East Africa (PUMPSEA) project
Transect and line method was chosen as a standard method to obtain quantitative descriptions of species composition and community structure
Total of 32 plots were sampled randomly
Plot size (10 *10 m2)
All trees were identified to species level
Information recorded
For adult trees, circumference (G130 cm)& tree height (m)
Regeneration classes (diameter < 8cm)
Cut stumps, only counted
Sampling (August-September 2005)

9. Aerial photographs and satellite image (IKONOS, 2005) processing
Purchased from Ministry of Land and Survey at Dar es Salaam
Year 1969, 1982 and 1992
Photographs scanned at 300 dpi
Imported into ArcGIS
Georeferenced with reference to the satellite image 2005
Assemblages were visually delineated

10. Sonneratia alba
Ceriops tagal
Rhizophora mucronata
Saltpan area
Avicennia marina
Identification key were made prior to delineation of dominant assemblage (Dahdouh-Guebas et al. 2006)

11. Results and Discussions (1)
Tree physiognomy
(a)
(b)
Box-plots display of adult mangrove Height (a) and G130cm (b) distributions at four transects in Mtoni-Kijichi.
Statistical test shows a significant difference in height and G130 distributions (p < 0.05, ANOVA),
Differences between transect 1-2 & 3-4 (p < 0.05 Post hoc Tukey HSD test)

12. Results and Discussions (2)
Distribution of species in the forest (Morisita’s index)
Io = 1, randomly dispersed
Io < 1, evenly dispersed
Morisita’s Index (Io) values
Transect
Species 1 2 3 4
A. marina 0*
0.0010
0.5747
0.0370
B. gymnorrhiza np
0.0392
0.0157
C. tagal
0.1078
0.0034
0.0003
L. racemosa
R. mucronata
0.0036
0.0005
S. alba
0.0001
0.0017
0.0071
X. granatum
0.0354
Io > 1, clustered
*np, the species was not observed and 0* value less that
Io > 1, the population is clustered, if Io = 1, randomly dispersed & Io < 1, evenly dispersed.

13. Results and Discussions (3)
Regeneration status
Statistical test
p < 0.05
Differences
Between the two groups
Seedlings: RCI (height, h < 40 cm ) , juveniles: RCII (40 < h < 150 cm),
small trees: RCIII (150 < h < 300 cm) and young trees RCIV h > 300cm
Ratio RCI:RCII:RCIII = 2: 1: 1
Kairo et al. (2002) found 86:51:1 (Uyombo) and 62:17:1(Kirepwe) in Kenya
Chong (1988) obtained ratio of 6:3:1(Costa Rica)

14. Results and Discussions (4)
Cut stumps status
Large number of cut stumps observed at transect 2
Statistics test shows a significant difference between transect 1 and 2- 4, p < 0.05

15. Results and Discussions (5)
Vegetation map produced from 1967 aerial photograph

16. Results and Discussions (6)
Vegetation map produced from 1982 aerial photograph

17. Results and Discussions (7)
Vegetation map produced from 2005 panchromatic satellite image
Position of dominant species remained the same

18. Results and Discussions (8)
Estimation of total area coverage
-5.3
-1.4
-10.6
% Change from previous image (mangroves only)
179.24
191.47
194.13
219.77
Total mangrove cover (ha)
207.83
202.20
266.72
Total area inclusive salt pan and cleared areas (ha)
2005
1992
1982
1967
Year

19. Conclusion
The mangrove of Mtoni-Kijichi comprises small assemblages of S. alba, A. marina, C. tagal, B. gymnorrhiza and R. mucronata (remote sensing). Field survey indicated the presence of L. racemosa, and X. granatum.
Taller and bigger trees (G130 > 8 cm) were found close to the river mouth while shorter and stunted trees dominated the southern part.
Regeneration class III and IV were more preferred by cutters
Large number of cut stumps were found at transect 2, with estimated 760 stumps per hectare
A total of 40.5 hectares of mangroves have been lost from 1967 to 2005, which corresponds to 18 % of the mangrove cover present in 1967.

20. Shall we clear all trees and forget that once there was a mangrove forest here?
Or shall we wait longer till they grow into bigger size?
Thank You