Where to Plant Trees in Cities?
There are lots of places to plant trees in cities – but we are told otherwise. Below are many of the traditional reasons/rationales given for this (to be debunked!). In believing these ‘objections’ we lose the myriad of benefits that come from having a tree canopy as an integral part of our street and home living spaces
Trees get ‘too big’ and their roots get into the foundation!
Trees come in many sizes so if ‘small’ is preferred, select a tree which reaches 30-50 feet at maturity such as Magnolia, Little Leaf Linden, Redbud and many of the fruit trees. In addition, a tree’s root system is only a problem if it can’t find water and the soil is too compacted. Healthy soil, which in turn creates healthy roots, will avoid these issues.
The leaves (and sometimes fruit) are messy and have to be cleaned up!
Yes, leaves need to be collected and composted each season, however leaving them on plant beds when seasons change and mowing them into the lawn will provide the organic food the soil needs. Globally we are short of organic matter so leaves are valuable – not a nuisance.
They fall over in big winds and take out hydro lines!
Trees grow extensive and deep root systems if the soils and sub-soils are opened up after construction instead of being heavily compacted. They only fall over when their root systems are restricted and miniaturized. Again, ideal soils – healthy roots.
Trees should be planted 20 feet apart so they can reach full-size one day (this assumption is changing nowadays and street trees can be seen planted as close as 10 feet apart)!
In the past we thought trees should have plenty of room to grow and become statuesque. Naturally grown trees found in a forest live close together, shade each other’s roots and soil, and share nutrients and water. A tree planted alone suffers the extremes of hot dry summers and harsh winters so root systems have only short seasons in which to expand – therefore most trees remain smaller than their potential. When we plant trees that grow quickly (often these are trees that naturally have a shorter a lifespan) with long-lived trees, then we replicate how nature enables both to survive and thrive.
Salt and pollution kill trees so it’s pointless planting them near roads!
Salt and pollution will, in large amounts, affect some of a tree’s growth, but if the available soil mass is large enough and the subsoil free-draining then the effect is minimal as the roots grow way beyond the reach of these factors. Trees are in fact often used to clean polluted industrial sites.
The maintenance expense is ‘too’ much!
Maintenance costs for trees over their long lives have to be quantified in relation to the everyday health benefits which they give to our city and to us as city dwellers.
Research shows that half of the trees we plant in cities slowly die over their first 20 years after planting so what’s the point of planting any!
That half of the trees we plant in cities die within 20 years is primarily due to their root systems not developing due to poor soil conditions and root inhibition caused by how we grow them before planting out. The strongest and most long-lived trees grow from seed. Their first priority upon emergence is to send down roots and if that root is a tap root it will go down 20 feet and more – IF IT CAN BREAK THROUGH THE COMPACTED SUB SOILS. Many of the young trees also die from drowning due to compaction levels around the planting hole.
All of these ‘stumbling blocks’ can be recognized and adequately dealt with before placing the tree in the ground.
When we prioritize the needs of a tree’s root system, using the knowledge we already have, e.g. that they benefit from shade and a shared healthy mycorrhizal system, then all the ‘rationales’ stated above and others previously used to ‘give up’ on having a healthy urban tree canopy will no longer have substance and we can create the urban forest we desire around us.