IMPACTS OF RAIN-FOREST LOGGING ON RIVER SYSTEMS AND COMMUNITIES IN MALAYSIA AND KALIMANTAN

The international political economy of tropical rainforests related to their perceived role in global climatic change has to be set against real national and local political economies. These political economies involve socially driven biophysical responses with economic and socia l costs whose magnitude and distribution need to be known if policy fo rmulation for improvement of living conditions is to succeed. Spatial linkages between changes and social costs, such as the downstream impa cts of logging, need to be established, but before that can be done it is necessary to distinguish the effects of natural processes from tho se induced by people. In Malaysia logging or ground clearance increase s river sediment yields by two to fifty times. Individual estimates ma y be unreliable indicators of the overall effects of change. However, the modifications to rivers as a result of raised sediment loads are i ncreasing year by year. Site-based studies of the effects of both logg ing and shifting cultivation help to improve the data base for policy making and also indicate the efficiency of reduced impact logging and agroforestry techniques.