Possible Effects of Forestry on Inland Waters of Tasmania: A Review

Abstract

Considerable public and political debate over the environmental consequences of large-scale operations associated with Tasmania's export forest industries prompted the present review and continuing field-studies. There are no known publications on the effect of forestry on inland waters of Tasmania, but relevant research in the Northern Hemisphere, the Australian mainland, and New Zealand, is summarized.Forest operations considered are roading, logging, and burning. In general, roading increases water-yield, reduces water quality, and modifies the physical structure of streams—particularly at bridge-sites. The impact of logging depends on the harvesting method used (generally, tractor and skidder-logging in Tasmania), the proportion of trees felled, the proportion of the catchment logged, and the precautions taken. However, stream-flows, sediment loads, nutrient levels, dissolved inorganic materials, and wood debris, all increase with logging. If riparian vegetation is cut, water temperature usually increases in summer and decreases slightly in winter, but temperature tolerances of most aquatic animals in Tasmania remain unknown. The effects of burning Australian forests are poorly understood, but there are changes in water-yield and a decrease in water quality.