The Role of Forests in Maintaining Stable Catchments.
 The long term productivity of water catchments is wholly dependent on the stability of the forests in those catchments. Where ever clearfelling and roading takes place there is significant erosion and loss of topsoil resulting in the siltation and organic matter contamination of rivers and streams, this problem is compounded in steep terrain.

Road into old-growth forest, Upper Florentine Valley. Zoned for logging.

The depletion of oxygen in waterways from decomposing organic matter together with sedimentation, are an important determinant of the viability of invertebrate communities within those waterways.

Following forestry operations, water run-off initially increases then gradually decreases as vigorously growing plantations or re-growth with their high corresponding evapo transpiration rates decrease run-off by up to 50% at around 40-50 years. Relative stability returns to water catchments at about 150 years plus.

Where logging rotations of less than 50 years takes place, catchments and water production are destroyed forever.

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Catchments with large areas of young trees whose underdeveloped root systems and low soil organic matter, unlike old forests, do not have the ability to store water for dry time flows, consequently their high water demands leaves less for streams or may dry them up altogether.  

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 The Tasmanian forest practices code does not recognise as necessary buffer zones around small ephemeral streams, channels or steep slopes which may facilitate the prevention of the contamination of waterways.