ABSTRACT
INTRODUCTION The precise extent of cleared forest land in Amazonia is not at present known, but probably totals some 8-12 per cent of the historic forest cover (Neto 1989). As far as the state of Roraima is concerned, the current extent of clearance is relatively low, but increasing rapidly as has been shown in the previous chapter. It is thus of relevance to examine the present and likely future impact of forest clearance on the environment of Roraima. The impact will be discussed at two levels, namely, the local and the regional. Local effects will be considered mainly in relation to forest clearance for cattle ranching and for small-scale agriculture. Attention will focus, firstly, on changes in soil chemical fertility on cleared forest land and, secondly, on soil physical changes and associated slope dynamics. Specific data will be presented from an area of forest clearance near Maraca Island in northern Roraima. The regional effects of forest clearance, which are currently rather speculative in character, will be considered in the light of prevailing environmental conditions and of relevant findings elsewhere.
