Characterisation of vegetation zones using GIS: the Maya Mountains of Belize
Data from satellite images combined with data from vegetation surveys can help foresters in Central America manage and conserve tropical forests.
Characterization and classification of forest types has long been regarded as essential to forest management. This involves determining the composition of forest areas and monitoring changes over time. Geographical Information Systems (GIS) allow the storage and manipulation of data from different sources and over many time intervals. Their use in monitoring forest composition has enhanced forestry management.
This approach requires detailed data on vegetation cover to be gathered over a specific period of time, and the individual vegetation zones to be characterized by means of plot-based research. GIS allows many different spatial attributes to be analysed. For instance, the location of similar vegetation zones can be analysed spectrally (using satellite imagery) and plot-based studies can be incorporated to look at similarities in species composition. The resulting data may be used to characterise each particular zone.
The aim of this is to provide the necessary quantitative and geographical analyses to aid the management of the Maya forests of Belize. Arc/Info GIS and the Erdas Imagine image processing system are being used.
It is intended to produce vegetation classifications for three different years (1995, 1996 and 1997) using satellite imagery supplied by SPOT Image, with a ground resolution of 20 metres. These vegetation surveys will provide a basis, together with topological, hydrological and soil data, for mapping vegetation zones at both the macro and micro scale. The end result will be a base set of data allowing time series analysis of the forest, which will in turn allow the careful monitoring of changes in forest composition over time. The data will also allow distinct vegetation zones to be mapped and the area they cover to be measured, which can then be related to the geology, hydrology and other interpretations of vegetation. Plot-based species composition studies will provide data on species type, diameter at breast height (trunk diameter measured 1.5 m above the ground) and location, which can be stored within GIS at different scales and analysed to characterise and delimit vegetation zones.
It is hoped that the use of this methodology will increase our understanding of the differences between vegetation zones, the species present and their relative abundance - thereby providing a foundation on which further comparative studies on the composition of vegetation zones can be based.
Illustrations
- The Raspaculo River, Belize.
- Satellite image draped over a three-dimensional model.
- Plot-based image from Belize.
For further information contact:
Malcolm Penn
The Natural History Museum
Cromwell Road
London SW7 5BD UK
Tel: +44 (0)20 7942 5523 Fax: +44 (0)20 7942 5529
Email the GIS unit