Why does the most important component of a tree still get neglected in urban forest design installation and maintenance?

Can you drive a car without a motor? Would you live in a building with structurally unsound footings? Can humans survive without major organs? The answer is no, and trees can’t survive without a healthy root system.

Now we can argue the merits of the single most important component of an individual tree and its function. In a robust debate, there will be some truth in other essential parts of a tree, its health and function, although in every situation, a healthy root system is essential.

A tree’s root system anchors it to the ground during its entire lifespan and serves the following functions:

  • It’s how water and nutrients are transported to the tree
  • It’s where most of the tree’s excess energy is stored
  • It’s where all the interactions and relationships between soil microorganisms occurs
  • It’s a place where the tree’s ‘community engagement and resources’ are shared between the tree relations and trillions of organisms can flourish
  • The network of root structures where individual trees can communicate and share resources between generations
  • It is where the tree’s ‘brain’ could be situated!

The root system is where it all happens for a tree, but in the urban environment, it’s where the tree is struggling to survive under conditions that could be explained as dysfunctional, dire, lonely and depressing.

If tree depression were to be acknowledged, we would have to start clinical rehabilitation focused on the root system.

Trees are wonderful organisms – magnificent entities that can have a potential lifespan much greater that of humans.

Scientific understanding of tree health and function has made extraordinary leaps over the past few decades. Over recent years some scientific research has attempted to make a connection with human based concepts of perception. In the endeavour to help humans to better understand the wider environment by using simple concepts we understand from our own kind. These concepts are not entirely correct as we have evolved differently to plants and animals.  We are fundamentally different from trees and lack the conceptual ability to truly understand them at this stage.  We must be careful in aligning similarity to human and tree function.

  • Trees may have brain like structures in the root tips
  • Trees can count
  • Trees remember
  • Trees communicate
  • Trees share
  • Trees have social family units
  • Trees are aware of their environment
  • Trees can self-heal
  • There is questionable research suggesting trees feel pain

These concepts are presented in simplistic ways for general benefit, but are much more complex than they suggest, when robust science is applied. Trees are not simplistic, although comparably humans are, and our reductionist thinking is our obstacle to greater understanding of the environment.

The choice of word is important, for example, we know there is a type of communication occurring between soil microorganisms and tree roots through chemical exudates in the soil, although this type of communication is not talking. So, the term” trees talk” is not entirely correct.

In his bestselling book The Hidden Life of Trees, renowned European forest ranger Peter Wohlleben talks about the family unit of trees.

“Trees in a forest have family bands, if they are friends and are from the same species they can live a much longer life span,” he wrote. “Like an old couple and one dies the other won’t live as long.”

Wohlleben explains that mother trees suckle the young through the interconnected root system sharing resources. Because infant trees in a forest environment only receive three per cent of the sunlight – most hits the taller trees, leaving the smaller ones shaded – a strict growth upbringing is required.

“A long-lasting childhood enables a tree to live much longer after the mother trees die,” Wohlleben wrote.

Wohlleben talks of the “Wood Wide Web” in a forest environment, a fast-moving sharing of information through root connection and fungal networks. Unlike a city environment, where internet connection is more accessible for humans, the Wood Wide Web has no connection or internet speed. He talks about individual trees disconnected from each other and their ancestors. Wohlleben describes these trees as street kids or class clowns surviving and growing without rules and boundaries. Inevitably leading to a reduced lifespan.

Although there is much more scientific research required to better understand trees and forest function, undoubtedly it is to the benefit of the planet, our environment, and our own longevity that we investigate and develop a wider empathy for all of Earth’s biota. For all our current scientific understanding about the natural world, will still have far to go. We are directly connected to nature whether we like it or not. It doesn’t hurt to stimulate our imagination, wonder and respect of the natural world through boundary pushing science if it helps us better manage what we are destroying. if you don’t agree, you might as well pack your bag and grab that long flight to Mars.

Urban forest design must embrace the understanding and importance of a healthy family unit for all inhabitants. Family planning, social cohesion and strong community values is not just a human design, it has been around for millennia. If we are to design, install, maintain, and grow the urban forest, we need to emulate how natural systems have done it effectively for thousands of years. An urban forest ‘Ministry of Health and Family Welfare’ could be established for trees. Where would such a ministry focus its attention? Just as humans have acknowledged, it starts with  younger generations contained within the family unit. Where is this unit’s interaction in the urban forest? In the soil right beneath our feet!

Soil health in the urban forest is in crisis. Major impediments to sustainable health in urban forests include:

  • Compaction
  • Poor soil structure
  • Toxic chemistry
  • Inadequate soil biology
  • Pollution
  • Impermeable surfaces
  • Root zone confinement
  • Incompatible competition
  • Low root:shoot ratio

These are all major impediments of a healthy and sustainable urban forest.

Root:shoot ratio is the balance between the above and below ground components of a tree. This ratio is not static, nor is it the same for every species of tree. What is consistent with this ratio is it is rarely balanced in the urban environment.

Imagine your favourite tree. Think about its trunk, branches canopy and height and roughly estimate this overall mass. Now imagine the amount of below ground mass (the roots). Do you think there is enough mass below the ground? What do you think is stopping healthy roots growing? Yes, that hard compacted soil, footpath, road, house footing, driveway, change in topography and even grass growing below the canopy are all impacts to a healthy root system.

Have you ever seen an urban forest tree blown over in a storm? What did the root:shoot ratio look like? I put my money on a low ratio.


A healthy root:shoot ratio and symbiotic function between plant produced energy and soil biology.

If urban forestry is to be successful and provide the benefits to us and future generations of humans, we need to develop a tree roots movement to better establish a healthy and sustainable urban forest.

Soil Health just as Human Health is complex in nature. It requires further scientific understanding, addressing major dysfunction, inadequacies, making change in policy leading to inevitable robust funding. Sound familiar?  Yes, these are all similar issues global human societies face right now.

Is Soil and Tree Health worth talking about? Do we have the expertise and scientific understanding?  Do we have the potential to make great change?

What do you think?