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VEGETATION MAPPING AND CLASSIFICATION IN MADAGASCAR  (USING GIS): IMPLICATIONS AND RECOMMENDATIONS FOR THE CONSERVATION OF BIODIVERSITY

Please refer to this paper as:

Du Puy, D.J and Moat, J.F. (1998). Vegetation mapping and classification in Madagascar (using GIS): implications and recommendations for the conservation of biodiversity. In: C.R. Huxley, J.M. Lockand D.F Cutler  (editors.). Chorology, taxonomyn and ecology of the Floras of African and Madagascar. Pp 97-117.  Royal Botanic Gardens, Kew.

KEY WORDS - Madagascar, Vegetation, GIS, Biodiversity, Conservation.
 

SUMMARY

A map of the ‘Remaining Primary Vegetation’ in Madagascar has been derived (Map 1) and divided into broad vegetation zones. It is based on the vegetation cover map of Faramalala (1988, 1995), produced from satellite imagery, and the classification of Humbert (1955). A map of the ‘Simplified Geology’, derived from Besairie (1964), has also been produced, with the geological categories grouped into broad rock types which are thought to have a strong influence on the vegetation they support and its species composition. These two base maps have been superimposed to show the extent and distribution of the remaining primary vegetation in Madagascar, classified firstly into broad vegetation ‘zones’ and secondly by the underlying geology into vegetation ‘types’ (Maps 2 to 5; see also Du Puy and Moat, 1996). These maps have then been compared to the map of ‘Protected Areas’ (COEFOR/CI, 1993), and analysed using Geographical Information Systems (GIS). Histograms produced show the extent of the remaining primary vegetation (in km2) classified according to the underlying geology, and the areas of each which fall within the current system of protected areas (Figures 1 to 5). These maps and data are discussed, and the major omissions in the current system of protected areas are highlighted. Conservation priorities are identified for vegetation types which are not currently protected or have only minimal protection, and the remaining areas of these vegetation types are mapped to show their current extent and distribution.
 

CONCLUSIONS

The maps presented here, and the histograms derived from them, can be interpreted as reflecting patterns of biodiversity distribution, and in particular plant diversity. If reserves were established in as many different vegetation types as possible (the vegetation types indicated by the vegetation zones subdivided by geological substrate), then the greatest possible diversity of species would be included in the protected areas. Some species distributions have already been shown to coincide with the geological categories used in this study, and it is probable that many more follow the same patterns.

The highlighted examples of the areas of importance for conservation in Madagascar are in no way exhaustive, but for the first time recommendations concerning conservation of plant diversity have been supported by statistical evidence. The main  vegetation types identified within this study which are largely excluded from or are inadequately protected by the current system of protected areas are summarised below (not in order of importance):

  • Deciduous, dry, southern vegetation (Map 3) on:
    1. Unconsolidated sands (Mikea Forest, Itampolo)
    2. Mesozoic limestones (Mahafaly Plateau)
    3. Sandstones (extension of the Beza Mahafaly reserve)
    4. Basement rocks and ancient Lavas and basalts (Mandrare River basin, north and west of Ifotaka)
  • Deciduous, seasonally dry, western forest (Maps 4 and 5) on:
    5. Unconsolidated sand (coastal plains between Morombe and Maintirano)
    6. Basement Rocks (SW of the Tsaratanana Massif)
    7. Sandstones (Forest of Zombitsy)
  • Evergreen, sclerophyllous (Uapaca) woodland on:
    8. Quartzites and marbles (‘Cipolins’), with associated succulent flora on exposed, non-forested areas (Itremo Massif, Map 2)
  • Evergreen, humid forest at low altitude (Map 1):
    9. Particularly at lowest altitudes (Vohemar to the Masoala Peninsula an around the Bay of Antongil, Manombo and other areas described in the text)
  • Eastern coastal forest (Map 1):
    10. All remaining remnants (described in the text, especially ensuring some protection for remnants in the south-east near Tôlañaro (Fort Dauphin)).
Traditional reserve boundaries, although often transgressed, are generally recognised locally. It is therefore recommended that, wherever possible, existing protected areas with a lower degree of protection should be upgraded and given more adequate protection rather than creating entirely new protected areas, for which it may be more difficult to gain local acceptance. Furthermore, protected areas can only offer true protection if adequate funds and personnel are made available and are assured for the future, and that the will to ensure continued protection is cultivated at a local and a national level.

We hope that this work will contribute to the planning of priorities for the conservation of biodiversity in Madagascar, particularly in the selection of areas suitable for the establishment of new reserves. The inclusion of habitats not currently covered by the existing series of protected areas will allow the inclusion of as much of the island's phytodiversity as possible.

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