by Neil Carleton
Between Almonte and Appleton is an extensive silver maple swamp along the Mississippi River. Commonly known as the Almonte wetlands, this unique landscape has been designated by the Ontario Ministry of Natural Resources as both a provincially significant wetland (PSW) and an area of natural and scientific interest (ANSI). It’s been a natural wonder and a public treasure. It’s dying.
This wetland has been a stable ecosystem for a long time, as evidenced by its significant size and the rich diversity of its distinctive flora and fauna over the years. The survival of silver maples there has depended upon the natural, seasonal cycles of the Mississippi River. When flooding occurs, during periods of naturally high water in the spring, the bases of the trees and their root tops are submerged. Silver maples in swamp conditions remain healthy as long as the water level drops and their root tops can dry out during the growing season in summer and early fall.
The root collar of a tree is the area of the trunk just above the roots. If this important arboreal section of a backyard or park tree is covered with soil, phloem cells can suffocate and disrupt the movement of food from the leaves to the roots. If the root collar of a swampland silver maple remains under water, the tree drowns. It doesn’t happen right away. A few years may pass while the root collar of a silver maple is submerged and the tree deteriorates under stress. Die-off is the consequence in subsequent seasons.
Dead trees were noted at the Appleton wetlands during the summer of 2006. In 2007 silver maples were listing and toppling. By 2008 the damage had spread and there were acres of dying, dead, and blown down trees. The destruction continues.
- Silver maples naturally like their feet wet. They grow well in swamp conditions along river shorelines as long as their root collars are allowed to dry out after the spring floods during the summer and early fall growing period. Under stress from sustained high water levels, they drown and die. 2006 photo courtesy of Al Seaman.
Upstream above Appleton the same type of wetland forest is healthy. Riverside trees downstream of Almonte look fine. Something about the river environment between Almonte and Appleton is killing the forest. Insect or disease damage, or any higher than normal river water flow over the years, has been ruled out as the cause. Although the Appleton wetlands look just like a forest drowning from the sustained high water effects of a new beaver dam, there’s no beaver damn downstream raising the river level.
Thank you to Mike O’Malley for nominating the silver maples of the Appleton wetlands.
Do you have a notable or favourite tree? Readers are invited to submit their nominations for an honor roll of trees in our area that could be featured in future articles. You can contact me at 613-256-2018, <ve3nce@rac.ca>, or Neil Carleton, 3 Argyle Street, P.O. Box 1644, Almonte, Ontario, K0A 1A0. I look forward to hearing from you.
My volunteer columns started in March 2010, as print features, to support the tree planting and tree awareness initiatives of the Mississippi Mills Beautification Committee. The contact for the Tree Working Group is Ron Ayling, 613-256-4617. In Carleton Place, the contact for the Urban Forest / River Corridor Advisory Committee is Jim McCready, 613-257-5853.
Until the next column, you’ll find me looking for and hanging out with shady characters.
