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

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

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

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

Source Dar es salaam Study site

Study site Mtoni kijichi mangrove

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

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)

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

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)

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)

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 0.000001. Io > 1, the population is clustered, if Io = 1, randomly dispersed & Io < 1, evenly dispersed.

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)

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

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

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

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

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

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.

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