When glaciers disappear, the bugs move in

August 27, 2008

Seemingly barren soil can be seen at the foot of the Puca glacier, which is retreating by 20 metres per year (Image: Sasha C Reed)Enlarge

We’ve all been stunned by images showing the dramatic retreat of mountain glaciers. Yet few of us have given much thought to what happens next.

Now the first study to look at how life invades soil immediately after mountain glaciers melt has an answer. Primitive bacteria step in to colonise the area, enrich the soil with nutrients, and even cement the ground, preventing landslides, say researchers who have studied the process in the Peruvian Andes.

A few studies have looked at the types of plants that colonise mountain valleys that were previously covered in ice. But before plants move in there is usually a period, which at high latitudes and altitudes can last several years, during which the newly uncovered soil appears totally barren (see picture, right).

To investigate what is happening during this period, Steve Schmidt of the University of Colorado and colleagues examined the soil at the retreating edge of the Puca glacier in the Peruvian Andes. Between 2000 and 2005, they sampled the top 10 centimetres of ground that was revealed as the glacier moved uphill at a rate of 20 metres per year.

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Posted in Earth Sciences, Environmental, Science and Technology