EPOW - Ecology Picture of the Week

When an Avalanche is a Good Thing

Avalanche chutes
Juneau, Alaska

Explanation:  There are few scarier moments in the mountains than hearing the massive low rumble of a snow or rock avalanche.  Avalanches have been the cause of sudden catastrophic destruction and loss of life.

But in the natural world, such disturbances have their surprisingly bright side.  

Avalanches change the local topography (the "microtopography").  They can mix organic matter into topsoil and create and redistribute nutrients.  They can open up otherwise closed forests, thereby creating early-successional environments and help in the establishment of new seedlings.

In the Alps, avalanches are known to enhance plant diversity.  In Chile, regionally endemic southern beech trees (Nothofagus spp.) depend on disturbances, particularly on snow avalanches. 

In northern forests, avalanches can create corridors of berry-bearing shrubs used by foraging bears and nesting songbirds.  

So the next time you're in the mountains and view an avalanche chute -- as long as people are not at risk -- think of the ecological benefits of this disturbance!

Information:
     Fischer, A., H. S. Fischer, and U. Lehnert. 2012. Avalanches creating high structural and floristic diversity in mountain mixed forests in the Alps. Biodiversity and Conservation 21(3):643-654.
     Veblen, T. T. 1982. Natural hazards and forest resources in the Andes of south-central Chile. GeoJournal 6(2):141-150.