Digital Analysis of Human Impact on Tropical Vegetation

The purpose of these studies was to develop digital-processing techniques for LANDSAT Multispectral Scanner (MSS) data to use in monitoring the effect of human activity upon Amazonian vegetation. The procedure involves: (1) development of signatures for major vegetation communities, and (2) measurement of the extent of vegetation modification by human groups. Study sites were located in lowland Peru and in the Amazon basin of Brazil, south of Manaus, where tropical ombrophilous forest is the dominant natural vegetation. Two groups are currently modifying the natural vegetation: native Indiana populations and representatives of the modern national economies. The mode of occupance of these two groups differs significantly. Indiana groups, who have traditionally shifted village location every few years, occupy scattered sites of limited a real extent. While the influence of representatives of the modern economy is more recent, it threatens to be far more disruptive and widespread. The methodology employed relies upon the use of GISS algorithms to develop signatures for major components of the Amazonian landscape. Even though the area covered by each Indiana village is small (approximately five hectares), it was possible to develop signatures because spectral character shifts radically when tree cover is removed for settlement. Search for previously unknown sites was concentrated in the ecological zone favored by traditional groups