Primary succession begins when glaciers melt

Receding glaciers leave exposed rock with no soil or organics of any kind.

Volcanoes and glaciers have one thing in common - they both utterly destroy the land they consume.  Their mechanisms of destruction are polar opposites.  The landscapes they leave in their wake are equally dissimilar.  But the fact remains that, once their influence has passed, there is no soil for life to begin.  The soil has to be made.

Making soil is a time-consuming process.  In cold climates where low temperatures and harsh conditions abound, it takes even longer.  Also, there is no soft substrate for roots to find purchase.  While vulcanism often has layers of volcanic ash that is fertile and suitable for plants to grow, glacier-eroded rock is hard and barren.  Fine sediments may not be present at all.

Lichens are the first sign of life to persevere.  Certain species can make their living on bare rock.  Lichens are a form of symbiotic life, a relationship between a fungus and algae where both benefit from the presence of the other.  Fungal strands called hyphae allow the lichen to attach to the rock where chemicals break down the rock surface to aid in nutrient extraction.  Water, in the form of rain, mist, or dew, also contains nutrients that the lichen can use.  Then there is the air, which contains the elements needed for photosynthesis.

Bits of crumbling rock, dead lichen material, and blown-in organic matter fall into crevices and form a rudimentary soil.  This allows mosses to start to grow.  Moss growth deepens and enriches the developing soil, which then leads to the growth of ferns and other simple plants.  These new layers of life bring in invertebrates that again add to the developing soil.  In time, there is enough organic matter that larger plants and animals can survive.  With climate change causing glacier retreat and an environment more hospitable to life, the continued development of soil will produce a mature ecosystem.  What that looks like will ultimately depend on what plants and organisms come to live there and the long-term nature of the weather.

How long the mature ecosystem exists depends heavily on the nature of the area.  Global warming, man's direct involvement, weathering and erosion, plate tectonics, and a host of other forces will influence that.  In a million years, the whole area could look dramatically different.

All it needs is time.

Thanks for reading.

Eric Svendsen     www.ericspix.com