NOT JUST A PRETTY PICTURE

Ice jams, such as the one pictured above, play a large role in determining the residents and physical structure of the ecosystems located within the Grand River floodplain at Ruthven. This is accomplished both through the physical action of the ice, and through deposited material.

When an ice jam forms, usually due to some form of obstruction, large chunks of ice are forced over the banks of the river, scouring portions of the surrounding floodplain and damaging or sweeping away vegetation. As a consequence, vegetation communities composed of hardy, early colonists and resistant early successional species are dominant in these almost annually disturbed habitats.

Ice chunks left behind in depressions in the floodplain when water levels recede form the basis for vernal pools that provide breeding habitat for spawning amphibians, while large deposited debris provide shelter and feeding opportunities for birds, small mammals, and insects. Seeds from species of vegetation resident upstream are deposited; some of which become established within the floodplain. Nutrient material and other organic debris is also left behind.

Sadly, much human garbage is also deposited when an ice flow causes the Grand River to overflow its banks. This has prompted an annual spring clean up by Ruthven volunteers.

Brian Pomfret,
Interpretive Naturalist