Home Articles Forest Vegetation Maps to Western Ghats

Forest Vegetation Maps to Western Ghats

Marie-Claire Guero, B. R. Ramesh1
Head Geomatics Laboratory, 1 Head Botanical Laboratory
French Institute of Pondicherry, H St. Louis Street, Post Box – 33, Pondicerry
Email: [email protected]

Information on the distribution of endemic species in Western Ghats was gathered in a geographic database and was combined to other ecological description.

From forest vegetation maps (1:250,000) …
The French Institute of Pondicherry (FIP) has launched in the 1970s a cartographic program for the Western Ghats area. Agreements were signed between the French Institute of Pondicherry and the State Governments of Karnataka, Kerala and Tamil Nadu for the preparation of forest maps at the scale of 1;250,000. These maps depict the actual state of the forests, their environmental conditions (climatic, edaphic, biotic, administrative) and their potentialities. It is obviously based on the experience gained from an earlier mapping programme at the scale of 1:1,000,000 for the whole peninsula. However, the larger scale of 1:250,000 calls for a higher degree of precision. Such an information becomes a base for carrying out new fundamental research concerning the structure, floristic composition and dynamism of the formations, and to serve as help decision making tools to the environment managers.

The 1:250,000 scale cartographic programme consists of 6 vegetation maps (fig.1). Five of which have been published (the reference year for the vegetation cover is given under brackets) :

Published in
Mercara – Mysore 1984 (1977)
Bangalore – Salem 1982 (1977)
Coimbatore – Kozhikode 1982 (1977)
Trivandrum – Tirunelveli 1992 (1977)
Belgaum-Dharvar Panaji 2000* (1989,1992)
Shimoga 1999 (1994)
*(to be published)

Fig.1 : Studied Area

This mapping synthesises different types of information. The cartographic synthesis gives particulars on several categories of information:

  • Characterisation of different vegetation.
    This is done combining phenology, physiognomy and floristic groups which are derived from the characteristic distribution pattern and abundance. Based on these combinations several vegetation types are identified. The major types include evergreen forests, deciduous forests, other wooded formation and plantation. The location and identification of vegetation cover are taken from satellite imagery (Landsat, IRS1C/1D 1:250,000 False Colour Composite enlargements) : a visual interpretation allows delineating different kinds of forest vegetation physiognomy classes, which are checked on the field, using a ground truth method. Simultaneously the floristic characterisation of the climax or related formations is delineated using the reference of 1:500,000 FIP bioclimatic maps. By integrating these two information layers, 134 types have been defined for the Western Ghats area (between Goa and Kanya Kumari).
  • Background of streams and water bodies.
    This forms part of the physical environment.
  • Biotic pressure and administrative information. The degradation of forests is mainly related to the intensity of the anthropogenic pressure. Therefore, the FIP vegetation maps include the following information :
  • The density of the population represented by towns and villages with a population over 1000, represented by symbols proportional to the size of the localities,
  • The road network, including the main forest tracks, in order to indicate the accessibility of forests,
  • The legal status of the forests, by delineating the territorial division of the forest administration and the protected and reserved forests.

Other recent maps
Specific 1:100,000 maps on the Nilgiri have been published in 1994 using the same methodology: four sheets are available at this scale on this area (“Nilgiri biosphere reserve area, vegetation and land use”, R.Prabhakar, J.P. Pascal; 1994; published by the Centre for Ecological Sciences, Indian Institute of Sciences – Bangalore and the French Institute of Pondicherry). One 1:100,000 scale map is to be published in the coming months on the Lingannamaki reservoir area (Karanataka) related to Rain forests, degraded forests and cultivated areas.

… to Geographic Databases
Since the creation of the Geomatics Laboratory in 1994, the FIP started building geographic databases based on the 1:250,000 vegetation maps, using the Arc/Info software package. The scope of the work consists in facilitating the digital composition of the forest maps, constituting an evolutive information system and carrying out spatial analyses and modelling on landscape and forest biodiversity.

Each map corresponds to a database. The databases contain the following layers of information : forest vegetation, streams, water bodies, roads and railways networks, localities over 1000, administrative units (states, districts), forest units (forest administration units, protected forests). Each information layer is documented with an encoded attribute table for the semantic characteristics of various features.

Of these maps, numbers 1, 2 and 3 which were created using traditional cartographic methods, are now in digital format. Map number 4 is yet to be digitised. Map number 6 of this series was published in 1999. This has been created using GIS potentialities. The geographic database related to map number 5 is now under preparation.

These geographic databases are actually used by the FIP in the context of specific research programs on a regional level. It is used in research projects whose scope includes understanding and modelling the changes of landscape and forest biodiversity in Western Ghats. In this context the vegetation cover in the Belgaum, Shimoga, and Mercara databases have been already upgraded, using recent IRS 1C/1D satellite images (1997). The information is also processed and combined with other sources of information for modelling environmental indices, for example, the soil organic carbon tenure has been spatially modelised in the Shimoga district area by applying a model C=f(soil, vegetation cover, climate)

… and multimedia application
With the aim of enhancing the knowledge on forest biodiversity, the department of Ecology carried out a research programme jointly with the Geomatics laboratory on the distribution of endemics species in Western Ghats : all the information was gathered in a geographic database (location of the endemics species, main forest types limits, bioclimatic zones) and was combined to other ecological descriptions. This work culminated in the publication of an Atlas of the Endemic species in Western Ghats and one interactive CD-Rom application was published in 1997 (“Atlas of Endemics of the Western Ghats, distribution of tree species in the evergreen and semi-evergreen forests”, B.R.Ramesh, J.P. Pasal, C. Nouguier, 1997 ; “Endemic tree species of the Western Ghats (India) CD-Rom”, R. Datta, C. Nouguier, J.P. Pascal, B.R. Ramesh, 1997).

The vegetation maps and explanatory notices, the Endemics species Atlas and Cd-Rom appplication are available for sale at the French Institute of Pondicherry. The databases are presently not made available outside the FIP, but new research projects can be identified using these information systems.