14 February, 2012

Forest soils are depleted

Freya Headlam, Glen Waverley
The Age, letter, 14 Feb 2012

AS SEVERAL letters note (The Age, 13/2), the two independents' decision to allow the burning of forest waste to count as creating renewable energy is a bad one for many reasons.

The main reason, however, is that it is not sustainable. The removal of so much organic matter means a progressive decline in the quality of forest soils. The leaves, twigs, small branches and sawdust left on the forest floor gradually break down to form a layer of humus that returns nutrients to the soil, improves its texture and protects it from erosion by wind and rain. This material helps the soil retain moisture, so that it acts like a giant sponge, holding rainwater and only slowly releasing it over many months. By contrast, after clear-felling, rain runs off from bare ground.

If we remove material from the forest floor, we are gradually running down our forest soils; the depleted forests will decline in quality and produce less and less (rain, timber) each passing year.

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