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APPLICATION OF GIS TO CONSERVATION ASSESSMENTS AT THE ROYAL BOTANIC GARDENS, KEW
GIS AND VEGETATION MAPPING
As noted above, currently only c. 3% of vascular plants have a global conservation status
using the IUCN criteria, and so in some areas, much more rapid methods of conservation
assessment may be required.
Analysis of vegetation maps in GIS can be a powerful tool for rapid conservation prioritization.
GIS analyses provide solid scientific data, which can be used for planning and management of
biodiversity conservation. This technique produces relatively rapid biodiversity assessments,
and so is particularly suited to conservation hotspots where information on the distribution
and rarity of the vast majority of plant species is scarce, and habitats are being destroyed
faster than individual species distribution data is being compiled.
Madagascar is one such conservation hotspot with high biodiversity and a high level of
endemism, which is under threat from habitat degradation and destruction. At Kew, the methods
described below have been used successfully in Madagascar to identify conservation priorities,
and similar techniques may be applicable in other conservation hotspot areas such as South-
East Asia.
Case study: vegetation mapping in Madagascar
Du Puy & Moat (1998) used the Papilionoid Legume specimen database to demonstrate that
certain parameters such as seasonality and substrate (underlying rock type) have an effect on
species distribution (see discussion above). Distinct preferences can be demonstrated for many
species, such as exclusive occurrence in seasonally dry or perennially humid habitats, on a
certain geological type such as limestones, quartzites or sand (Du Puy & Moat 1998). A more
informative vegetation map can therefore be made by dividing the broad vegetation zones
into narrow vegetation types based on rock type, which reflect the distribution of individual
species, so that each type of vegetation contains its own distinctive range of species. This
subdivision of vegetation zones based on underlying rock types is therefore a way of rapidly
estimating patterns of individual species distributions. If as many vegetation types as possible
are included in reserves, the resulting network of protected areas will contain as large a diversity
as possible. This technique has been successfully applied to conservation and planning and
management of protected areas in Madagascar (Du Puy & Moat 1996).
Initially, a map of remaining primary vegetation in Madagascar was derived from satellite
imagery. Classification and mapping was done by remote sensing techniques, using Landsat
and Spot data (Faramalala 1988).
In the next step, a geological map was digitised and simplified to rock types affecting vegetation
(e.g. limestone, lavas etc). A composite map was then produced, of vegetation zones and rock
types, showing patterns of variation within vegetation zones (Fig. 3). Each vegetation zone
subdivision (vegetation type) will contain a different suite of species, so the maximum number
of species can be preserved by conserving as many of the vegetation zone subdivisions as
possible.
The current degrees of protection for each vegetation type were quantified, by overlaying a
map of protected areas onto the vegetation types map. Amounts of protection for each type
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