Those of us who love and protect forests know that they help stabilize watersheds and clean our drinking water, but until a recent report, we were unaware that trees helped form our rivers and floodplains 330 million years ago!

A river in southern Montana in Yellowstone National Park. Credit: Carolyn Conner

During the Palaeozoic era, Earth’s landscape was alluvial, meaning it was predominantly deposits of sand and mud thanks to flowing water. But this would all change during the Carboniferous Period when tree-like plants arrived on the scene. A recent report in Nature Geoscience by Neil Davies and Martin Gibling from Dalhousie University, Halifax, Nova Scotia, Canada, reveals that these early trees’ deep roots established themselves along the alluvial terrain, morphing the flowing water from shallow, wide expanses to deeper, narrower channels along floodplains. The “modern” river was born.

Forests began to take root and plant life flourished. Plants became more complex and began forming coal deposits upon their death, a carbon basis that is still very prevalent in life today. This period of time is actually named after this activity.

The stabilized floodplains became increasingly fertile due to the combination of the rivers and trees, and over the centuries, these floodplains would form the basis of early human civilization and agriculture.

Today, forests provide 60 percent of America’s fresh water, filtering rain water before it enters our wells and city water systems. Trees also filter industrial and agricultural runoff before it enters many of our waterways and helps stabilize the land around them. So next time you’re enjoying a river or stream, look around and thank the trees for helping make it all possible.

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