With the recent rains, we have been thinking more about the role trees play in helping us manage urban stormwater run-off.
As many of us know, trees help slow rainwater down with their leaves, needles and bark, this water is collected and gives processes like evaporation a chance to do its thing.
And the rest of the water falls to the ground.
Leaves and plant debris play a part in regulating soil temperatures and moisture levels allowing beneficial organisms to help break down organic matter thus adding important nutrients to the soil. This layer also keeps the rainwater in the soil and not get washed away carrying heavy metals and pollutants. And of course the roots hold the soil in place and absorb water.
We came across some interesting articles about rainwater and trees. Including this 2004 The Guardian article that looked at stormwater and how much rain woodlots in Wales were able to absorb versus lands grazed by animals. The result? Woodlots held 60 times more rain. Scientists theorize that part of the reason is that the grazing animals compact the soils and that tree roots provide passages for the rain to go elsewhere versus running off.
Closer to home, a TD Bank Economics report noted that Toronto’s trees are valued at approximately $81 million in benefits, approximately 66% is how trees help manage their stormwater. As well, for every dollar spent on tree maintenance, their urban forest returns that value from $1.35 to $3.20 in benefits and cost savings per year.
Lastly, we found this Canadian Geographic article about Elmvale, having the purest water than ice layers in the Artic. A combination of tree roots, plant materials and soil types all play a role in their very clean water supply.
Trees are so cool!