By Shelby Perry –
“There is magic in running water, for after I have thought its life history all out there is still much unexplained.”
These are the words of my great-grandfather, from a book he wrote ninety-three years ago called Man’s Spiritual Contact with the Landscape. I never met him, as he died long before I was born, but from his words I can tell that we have much in common.
Every morning I walk beside the LaPlatte River in Shelburne and contemplate the life history of its waters. One morning this February a frozen flood made the magic in those waters visible. Rain on snow during a warm snap caused the level of the river to rise quickly during the night. By morning the river was several feet above its normal water level. The water fell gradually, but the temperature plunged quickly, and during the next night a thin layer of ice formed on the surface of the waters, marking the height of the water at the coldest part of the night. It was as though someone had pressed a pause button on the flood, and an eighth-inch-thick sheet of ice clung to trees and sticks, hovering six inches above the ground.
My dog and I crashed through this frozen landscape the next morning and reveled in the sparkling beauty of a world draped in a silver cloak of ice. Now, in April, the flood plain no longer sparkles, exactly – it wears the drab browns and greys of early spring. Bits of green poke through here and there, but for the most part every surface is still coated with the fine layer of silt left behind by receding flood waters. I revel in this landscape, too, because a functioning floodplain ecosystem is a beautiful thing.
That thin layer of silt represents a fresh collection of nutrient-rich sediment for the hungry plants and trees of the flood plain. The plants of the flood plain are specially adapted to live in this water- and nutrient-rich environment, and they often depend on annual flooding not just for nutrients, but also to spread their seeds and carry away any less well-adapted competition. Different plants adapt to different environments of the flood plain, some preferring the naturally formed berms just beyond the banks of the river, while others are more suited to the slow-to-drain boggy back-swamps. These, too, depend on flooding for their formation.
Roiling and fast moving flood waters contain a lot of energy, enough energy to carry much more than just silt. Sand, stones, and larger sediment often get swept up and transported long distances in a rushing spring river. When a river leaves its banks it immediately loses much of its energy. The water slows and spreads out across the floodplain, dropping first the heavy sediment, such as sands and gravel, and then the finer silts and organic materials further out. This sorting by size is what results in the gentle berms immediately past the banks of the river, and the silt that travels further is smaller, so it packs more tightly together when it reaches the ground, creating the slowly draining back-swamps beyond the berms.
Right now, in the pools of flood and melt water filling the back-swamps, peepers and wood frogs sing their spring chorus of lust in hopes of attracting a mate. These swamps and pools dry completely late in the year, and so sustain fewer aquatic predators that might eat the breeding amphibians or their eggs, so these pools are important for their survival. And their survival should be important to us, because amphibians are the main predators of mosquito larvae, who also favor the standing waters of back-swamps. Another frequent inhabitant of back-swamps, eastern newts, are capable of eating over 300 mosquito larvae in one day.
Many mammals also rely on the floodplain forests for their survival. Chipmunks and minks prey on the amphibians, and then in turn feed foxes, coyotes, and bobcats. Beavers are the architects of the channel, building dams and lodges that move the flow, eroding this bank or that, building sand bars with the changing flow path. Birds ranging from tiny wrens and finches all the way up to red-tailed hawks, ravens, and turkey vultures also feed on the life that surrounds the river.
My grandfather’s book included a chapter for each month of the year, but he began with the running waters of April. As I walk beside the river each morning it is not so difficult to see why, for the river and its tributaries are like veins through the landscape: they carry life. Life that wakes and grows and flies and sings in April. So next time you find yourself beside a river in April, look beyond the dull grey patina of silt and enjoy the magic that is running water.
Shelby Perry is a second year student in the Field Naturalist program. Her great-grandfather, Stephen F. Hamblin, was the author of the book Man’s Spiritual Contact with the Landscape and co-author of Handbook of Wild Flower Cultivation. He was a professor of horticulture and landscape architecture at Harvard University and the Rhode Island School of Design and founded the Lexington Botanic Garden.