Consider the Trees: A Look at Water Runoff and Tree Health

Trees provide shade, temperature regulation, wildlife habitat, and hydrologic (water runoff) regulation in cities. It’s important to provide them with everything they need to thrive, so that we can also thrive. 

https://findanexpert.unimelb.edu.au/news/5406-how-tree-bonds-can-help-preserve-the-urban-forest

Impervious cover, or in other words concrete streets and sidewalks, lead to more water runoff.. All water eventually ends up draining into our lakes, rivers, and oceans. And when there’s more impervious ground, there’s more water runoff because the water can’t absorb into the soil. This leads to polluted water and makes it hard for trees to get proper nutrient uptake through their roots. 

The MN Stormwater Manual outlines studies that show how beneficial tree canopies can be for urban environments. “Uptake of water from trees limits the volume of runoff discharged downstream, and their canopies offer interception of rainfall and shading (cooling) in an urban environment. Trees also absorb nutrients that could otherwise run off to local receiving waters” (Minnesota Stormwater Manual).They naturally filter runoff, stabilize base flow, and reduce erosion in streams. 

Trees hold nutrients in their leaves, when rain falls through the leaves to the ground, it brings nutrients to the soil – this is called “throughfall.” It’s an important natural process that allows for high survival rates. Roots spread horizontally just as much (or even more so) as they do vertically. 

https://news.vt.edu/articles/2012/11/112112-cnre-treecanopymapper.html

Urban boulevards are not an ideal place for a tree to thrive because of the limited root spread in a limited space. So we have to work extra hard to ensure these trees have the space and nutrients they need to grow. When they are boxed in among impervious street cover or just not given enough space, their lifespan is stunted. 

The future of urban forestry is delicate. We must make sure that everyone can live long healthy lives. So let’s consider the trees!