A GIS based methodology for small scale monitoring of tropical forests—a case study in Sumatra

Abstract

A Geographical Information System based methodology was developed in the framework of global survey of tropical vegetation using satellite data; it was tested on the forests of Sumatra with time series of NOAA AVHRR GAC and LAC data of 1982, 1988 and 1989. After some geometrical registration and radiometric optimization, these data are processed through a mono-date approach for minimizing the strong and highly variable atmospheric effects. Final results are derived from superimposing single-date classification outputs. Due to the low resolution of satellite data and the small size of local systems, adequate reliability for sampling and classification processes require the introduction of geographical information (topography, soils, bio-clirnates); iterative interactive procedures are used for that approach. Elevation is especially useful due to the altitudinal zonation of natural vegetation. Different classification rules based on satellite and geographical information are tested and compared for assessing the potential of NOAA AVHRR data for small-scale survey of tropical forests. Finally, the vegetation maps of Sumatra in 1982and 1988 are obtained, and the on going deforestation rate is estimated.

Improving Landsat and IRS Image Classification: Evaluation of Unsupervised and Supervised Classification through Band Ratios and DEM in a Mountainous Landscape in Nepal

“…in the image classification process, and earlier studies have demonstrated the use of a DEM for a number of purposes [1]. DEM integration in image classification has helped increase the classification accuracy of digital data [7][8][9][10][11][12]. A DEM has also been used to describe the distribution of terrain components which contribute to spectral response [13], identify sites for fieldwork [14], geographically stratify training areas or homogeneous regions [17], and provide topographic normalization of Landsat TM digital imagery [16].…”

Geographic information systems (GIS) and the conservation and use of plant genetic resources.

“…Remote sensing has been used to document and model changes in the extent and characteristics of forests (e.g. Skole and Tucker, 1993;Gastellu-Etchegorry et al, 1993), 16 wetlands (e.g. Sebastini et al, 1989), deserts, 17 different land use types (e.g.…”

Vegetation characterization and land cover mapping with NOAA‐AVHRR data in the wet tropics

“…Given the volume of data to be analyzed, there is, however, a need for an automatic procedure providing an objective reliable vegetation classification adapted to the AVHRR resolution (Malingreau, 1992). The aim was therefore to investigate the potential of the AVHRR tool to carry out a forest/non-forest classification without a preliminary sampling stage (using thematic informations such as maps, field data) such as is used in a supervised classification process (Cross, 1990;Gastellu et al, 1993). The output classification produced from this work has to be based primarily on the satellite data providing the advantage of an easy continuous updating as new data are acquired.…”